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Welcome to the course Ergonomics in Automotive Design Now, we are going to discuss our 5th module that is in-vehicle and external visibility of the driver So, under this module, we will discuss four topics; first one – human field of view, second ñ driverís field of view inside vehicle and outside vehicle, third one – field of view through windshield and windows, and fourth one – field of view through mirrors; side mirrors as well as rear-view mirror Now, first, we should know; what is field of view? So, while we are discussing about human field of view So, we need to understand; that what is field of view? So, as per the definition, we can define field of view as the region or extent of the external world or space which is visible at an instant during steady fixation of gaze in one direction So, when we are looking at a particular direction, at that time, the extent of the external world which we are perceiving through our eyes, that is the field of view Now, according to Society of Automotive Engineers (SAE), J standard, J985, the extent of visual field; if we look to this figure then the; for left eye If we consider the left eye, the monocular field of view, means, only by left eye, we can see 150 degree So, starting from one side; left side, up to 90 degrees, that is the mid-line, straight forward line, and across the nose, we can see another 60 degree So, this side 90 degree, and so, first portion, this is 90 degree and after that another 60 degree So, total 150 degree, this is the monocular field of view for left eye Similarly, for the right eye, from the side-line, we can see up to 90 degree on the same side; right side and across the nose, we can see another 60 degree So, total 150 degree So, this is the monocular field of view for the left eye, and this is a monocular field of view for right eye Then, the overlapping area So, this middle portion, this is the overlapping zone So, the size of the overlapping zone, that is the binocular field of view, that is 120 degree So, whereas, monocular field of view for both the eyes is about 150 degree, but the binocular field of view 120 degree Now, so, one aspect is monocular field of view while we are visualizing the external world by either left eye or right eye While we are looking the external world; the common zone for both eyes; right and left that is called binocular field of view The third area; that is the ambinocular field of view, that is actually the sum of field of view, for the both eyes So, both for left eye and right eye; total how much area we can see, that is the; from this point to up to this much, means, 180 degree; where there is only by the left eye, only by the right eye; at the same time both left eye and right eye So, monocular field of view, binocular field of view and then again monocular field of view for the right eye So, this total zone is defined as the ambinocular field of view Now, binocular field of view; vertically if we consider, then it is 50 to 55 degree upward and 60 to 70 degree downward So, downward field of view is more Binocular field of view; as defined by the Henson (1993), it is 60 degree vertically, 25 degree up and 35 degree down Now, if we see the perspective view of binocular field of view, earlier what we were discussing, that was the horizontal field of view, but if we consider both; horizontal field of view as well as vertical field of view, then how much is the binocular field of view? So, if we look at this image So, this is the left eye, and this is the right eye For left eye; this is the monocular field of view for the left eye Similarly, for the right eye; this is the monocular field of view, then the middle portion, this common zone, that is called binocular field of view for the both eyes

So, binocular field of view is; this zone So, within binocular field of view; images are sharp, depth perception occurs and colour discrimination is possible So, this binocular field of view is very important from our visualization of the external world Now, while we visualize external world or we are looking at the object in our external world or perceiving visual information or light rays are coming and entering through our eyes, then we perceive different information This visualization is not only eye dependent, that is actually, depends on the movement of eye as well as neck Sometimes, we see only using our eyes; left eye, right eye and sometimes we move our neck to visualize object and there is also other situation, where we move both our neck as well as eye So, only eye movement is possible, only neck movement is possible, at the same time neck and eye both moves together to visualize object So, now, here we are discussing the range of motion of the neck or range of movement of the neck So, generally, maximum and easy reach So, easy neck movement reach, easy head movement or neck movement, whatever is possible, that is a, if we see the lateral view, means, 45 degree left and 45-degree right Similarly, maximum head movement or neck movement may happen, that is 60 degree left, and 60-degree right On the other hand, if we consider the up-down movement of the neck, then easy neck movement or head movement, it is 30 degree up and 30 degree down, and 30 degree up, whereas, maximum neck movement is 50 degree up and 50 degree down During viewing; either both eyes and/or neck movement occurs, as we discussed earlier, to project the image on the retina So, in this image, what is shown? As we already mentioned, that is horizontal, that is the left part, and this is the vertical range of head and neck movement Now, we can categorize our field of view, like stationary field of view, eye field and head field So, now, what is stationary field? So, visual targets within a visual angle less than 30 degree; when we are looking at a particular point, around that line of sight, within a 30-degree view cone, whatever information is presented, that we can visualize without significant eye movement So, significant eye movement is not required Although eye always moves, dwell always happens, but significant eye movement is not happening within a view cone of 30 degree So, without significant eye movement we can visualize the information presented within a view cone of 30 degree, that zone is defined as the stationary field of view, where significant eye movement not required Next point is eye field In case of eye field; target presented within an angle of 30 degree to 80 degree view cone, then what happens? Supplementary eye movement is required, while we are looking at a particular point, without eye movement, it is not possible to visualize any object or any information or any visuals presented within a view cone of 30 to 80 degree So, there eye movement is required, that is why that field of view, that zone is called eye field The third area is head field While we are looking at a particular point, that line of sight, around that line of sight, if any information, visuals is beyond the 80-degree view cone, then head movement is required So, that field is called head field So, while we are pointing at a particular, say for example, for any human being, while he or she is pointing at a particular location, around that line of sight, up to 30 degree, there is no significant eye movement, that is called stationary field; after that, if he or she wants to see, then there is requirement of eye movement So, up to 80 degree, he can see with the help of eye movement, that is a eye field, and beyond that, if he or she wants to see, then he or she has to move the neck Vancott and Kinkade (1972) mentioned the comfortable viewing angle So, 15 degree is a comfortable viewing angle for positioning most important display or most frequently used display So, our laptop, monitor or display screen should be positioned within an angle of 15 degree below the horizontal eye level Similarly, if the number of displays are more or there is requirement, that for frequently used comfortable viewing, where frequent changes of gaze between two or equally important visual targets, where number of visual targets is more, we have to shift our eye from one point to another point or one display to another display, then the display should be positioned within an angle of 30 degree, so, that we can comfortably visualize those displays Grandjean (1987) mentioned about the comfortable viewing distance

So, what is the comfortable viewing distance? Comfortable viewing distance is approximately 50 centimeters, while the character height or the font size is 3 to 4.3 millimeter Centre for Disease Control, USA in 2000, prescribed that comfortable viewing distance ranges between 46 centimeter to 76 centimeter away from the eyes for visual display unit workstation Now, we are moving to the human field of view; the visible spectrum of electromagnetic radiation From this image, we can see electromagnetic spectrum Out of this, only this zone, that is starting from 380 nanometer to 760 nanometers, within this range of electromagnetic radiation human can see object So, human eye is sensitive within this electromagnetic wavelength So, that is 380 to 760 Now, to understand human field of view, it is very important to understand the anatomy of eye, different parts of the eye, that how light enters inside the eye and image is formed So, for that purpose, now, we are going to discuss about the anatomy of eye So, if we take the cross-section of eyeball, then what we can see? There are mainly three layers So, the innermost layer, you can see in yellow color, here, that is the retina Next, there is another layer called choroid, then the third layer is the Sclera So, when we see from the outside, that white portion of the eye, that is actually the Sclera Now, from the front portion, the outermost layer of the eye, which is visible from the outside, that portion is actually, this is that one, so, that is called Cornea So, first one is the cornea, after that there is another, this is, this zone is called Pupil So, how Pupil is formed? There are actually Iris muscles; two types of Iris muscles are there So, one is a radially arranged and another is concentrically arranged So, Iris muscles, at the centre of the, this Iris muscle arrangement, there is a hole, that hole is called Pupil So, this Pupil is actually, the diameter of the Pupil is maintained by the muscle tone of the Iris muscles So, while the radial Iris muscles constrict, then the diameter of the Pupil increases, whereas, concentric Iris muscles contract, then the diameter of the Pupil reduces So, behind the Pupil, there is a Lens and Lens is actually suspended through suspensory ligament and attached with this ciliary body So, ciliary body and ciliary ligaments actually hold the, this is the Lens So, from the outside So, first portion is the Cornea, then there is a chamber; liquid field chamber, that liquid is called aqueous humor; after that there is a hole, that hole is called Pupil, then there is the Lens, and after the Lens, there is another chamber, that chamber is filled of jelly like material that is called vitreous humor So, outside chamber, that is filled with aqueous humor and inside chamber is filled with vitreous humor Now, when light rays enter from the outside, then it actually passes through; first, cornea, then enters to the Pupil, then from Pupil, it enters through the Lens, and then vitreous humor and ultimately falls on the Retina And while the light rays is falling on the Retina, then there is some electrochemical changes, then it leads to electrical potential and that information goes to brain and perception about the image happens So, on the Retina, there are different types of photoreceptor cell, generally, two types of photoreceptor cells are; these are called rod cells and cone cells We will discuss in subsequent slides Now, as I mentioned, the earlier slide So, from any object, say for example, one object is presented, its top portion is ëaí and bottom portion is ëbí So, from that object, light rays enter through the Cornea, then passes through the Pupil, then through the Lens, and ultimately falls on the Retina, and on the Retina inverted image is formed So, ëaí was up and ëbí was down; here ëb dashí and ëa dashí So, it is one inverted image is for me So, light rays enter and passing through different segments, and ultimately falling on the Retina and in the Retina, there is photoreceptor cells, where the photoreceptor cells, there is generation of electrical potential and that impulse transmitted towards the brain And now, important aspect is this zone The point on the Retina, towards the nasal side, with the nasal, towards the, at which

blood vessels and nerve fibers pass by, is called Blind spot No image formation occurs in this particular zone So, we are going back to the earlier image So, this particular area, this area is called Blind spot because the nerve fibers and blood vessels are passing by through this area, and there is no photoreceptor cells As there is no photoreceptor cells, so, there is, for example, if light rays comes like this, and falls on this particular area, then there is no formation of image because there is lack of photoreceptor cells So, that is mentioned here So, what is Blind spot? So, Blind spot is the point or is the area on the Retina, where there is no rod and cone cells and the through that particular area blood vessels and nerve fibers are passing by and that area is mentioned as Blind spot Now, there are various intrinsic muscle inside the eye Apart from that, there are extrinsic muscles, which actually regulates the eye movement So, if we look at these two images So, eye have different types of movements So, one is abduction, another is adduction So, adduction and abduction, means, this, towards lateral side or medial side; these type of lateral or medial movement of the eye happens with the help of medial rectus and lateral rectus muscles On the other hand, up-down movement of eye, that is the elevation and depression, it happens by, with the help of these two muscles So, one is called superior rectus, and another is inferior rectus So, superior and inferior rectus, here it is also mentioned; superior or inferior rectus, when superior or inferior rectus muscles contract, then what happens? The eye moves upward and downward On the other hand, rotation of eye happens, when there is the constriction or contraction of superior oblique muscle as well as inferior oblique muscle Superior or inferior oblique muscle is attached with the eyeball in such a way, when this muscles contract, then eye actually rotate So, understanding of the eye movement is also important for understanding the human field of view as well as in this automobile design, the driverís field of view The Cornea, the humours, as we mentioned, the first chamber, the first outside chamber, where this liquid is filled, called aqueous humor So, this portion, the Cornea, the humours and the Lens are the main refractive apparatus of the eye So, these are the main refractive apparatus The refractive power of the eye is measured in terms of diopters, this is the unit of the refraction capability of the eyes The eye has a single lens of 17 millimeter in front of the retina It has refractive power of 59 diopter So, the eye have total refractive power of 59 diopters About 48 diopters of the eyes, total refractive power is due to the cornea So, only due to the cornea, the refractive power of the eye is 48 diopters rather than the lens because the outside air, its refractive index is 1, then the corneaís refractive index 1.38 So, there is huge change in the refractive index between these two mediums; air and the cornea So, at this point, maximum refraction occurs So, that is why, the total refractive power of the eye that is 59 diopters; out of this 48 diopters refraction happens only due to cornea So, in this image various parts of the eye and their refractive index are mentioned Now, due to the refract; variation in the refractive capabilities of the eyes, there different scenario or different situations happen, like, if the eye condition is normal so, that is called normal or emmetropic eye, where parallel light rays focused sharply on the retina So, while parallel light rays are coming and entering through the cornea, then pupil, then lens and ultimately it is falling on the retina, so exactly properly, it is falling on the retina So, this type of; if it is properly happening; that parallel light rays are coming, and it is ultimately projected on the retina, then that type of our eye is called normal or emmetropic eye Next, category is the hypermetropic eye or farsightedness; in this case what happens? Parallel light rays enter inside the eye but form the image or focused behind the retina So, this is the retinal surface, it is forming the image behind the retina So, this type of situation is called hypermetropia; another condition, we call it myopia and the eye is called myopic eye; it is also known as nearsightedness When parallel light rays are focused at a point, some distance, in front of the retina So, this is the retina surface but actually the parallel light rays are focused to some

extent forward of the retinal surface So, this type of phenomena is called myopia and that eye is called myopic eye Now, for this type of condition; how it can be corrected? So, for that purpose, different types of lens are used So, one; we can correct this type of hypermetropic eye with the use of convex lens While we are using convex lens, then convex lens direct the parallel light rays in such a way, so, that it can form the image on the retinal surface On the other hand, in case of myopic eye; what is happening? The image is actually forming in front of the retinal surface So, in that case, if we use concave lens; earlier case it was convex lens; now, if we use concave lens, then what is happening? That parallel light rays actually focusing on this retinal surface So, this type of hypermetropic eye or myopic eye can be corrected with the help of different types of lenses Now, we will discuss about the accommodation; what is the accommodation for eye? The lens can change its refractive power So, lens has the capability; it can change the refractive power; how? By changing its shape or the focal length The lens can change its refractive power by changing the focal length; enabling light from both distant object as well as from the nearer object; it can focus sharply on the retina; this process is known as accommodation So, lens has the capability to change its focal length and focusing the light rays; either parallel light rays or divergent light rays, it can focus in such a way, so, that the image is formed on the retinal surface or the light is properly focused on the retinal surface and particularly in the foveal area, while eye movement is happening Now, in this accommodation process; how lens actually reacts? So, while divergent light rays are coming from the near object So, this type of lights are coming, then how is the lens shape? Lens is in spherical shape, at that time lens is spherical Due to spherical shape, that divergent light is refracted more and falling on the retinal surface On the other hand, while parallel light rays are coming from the object at longer distance, then lens changes it is shape to a flatter one; flat shape Then, the light rays are focused on the retinal surface So, in this way, lens can change its shape and helps in focusing the light rays on the retinal surface So, an eye with normal accommodation capability can focus on object located at a long distance, that is far away or infinity to objects as close as 90 millimeters; means, 9 centimeters So, far distance; we can see infinity distance On the other hand, as the near distance, we can see as close as 90 millimeter or 9 centimeter Now, on the retina, there are different types of photoreceptor cells; one is rod cell; another is cone cell So, this is the schematic representation of rod and cone cells Based on the intensity of light, the activity of rod and cone cells changes So, during daylight, while the or bright light condition, that is called photopic vision, mainly cone cells become active On the other hand, while there is low level of illumination, during night, then that type of vision is called scotopic vision and that vision is actually perceived by rod cells So, for photopic vision or daylight vision or bright light vision it is actually done by cone cells On the other hand, night vision or dim light vision happens using rod cells, that is called scotopic vision But in between, there is, during dusk or dawn, when there is relatively low illumination level, then we call that vision is mesopic vision and that during mesopic vision; both cone cells as well as rod cell participate In our eye, on the retina, there are about 125 million rod cells scattered across the different parts of the retina, except foveal region, that foveal region is the specific region on the retina, so, that is very important because, there is the; again, we are going back to this image So, if we look at this particular image, then this area; little bit depressed area on the retinal surface which is on the visual axis So, when light rays enter this visual axis, actually light comes on this particular depressed area on the retinal surface This point is called fovea centralis or foveal zone, where there is maximum number of or

most densely packed cone cells and this is most clear vision or visual clarity is possible in this area, that is called foveal area Now, about 70 million cones are densely packed in foveal region So, the densities 140,000 cones per millimeter square Now, fovea with greater temporal and spatial resolution due to its cone cells; acquire information faster than in the peripheral parts of the visual field So, as in the foveal region, cone cells are densely packed So, it has the greatest temporal and spatial resolution, and it has the capability to process the visual information faster Now, if we consider the visual acuity; but first, we should know, what is Visual acuity? For a fixed gaze angle and a focus distance, visual acuity is defined as the angular separation between two just perceivable points So, while we are looking at a particular point or fixing our eyes at a particular focal distance, then visual acuity is defined as the angular separation between two just perceivable points, as defined by Stenstrom (1964) Now, in details, if we try to understand; what is visual acuity? So, as we mentioned; the foveal region with cone cell it has the maximum visual acuity So, now, if this is, if you consider So, this is the distance from the fovea So, this is the center point; these 0 degrees, it is a foveal region From the foveal region, if we move towards the periphery, that is the, towards temporal retina, means, and another is the nasal retina; either towards nasal side or towards the temporal side If we move, with the increase of the angle; view cone angle; what is happening? The density of the cone cells at the foveal region; 0 degree, this is the straightforward line or that is the visual axis So, around that visual axis, near the 0 degree, the concentration or density of the cone cell is the maximum So, at this point density is the maximum As it was; we mentioned earlier, 140,000 cone cells per millimeter square region After that, drastically, the density of the cone cells reduces towards the periphery but in case of rod cells, the density is maximum, in this zone There is no rod cells at the foveal area but after that, the density of the rod cells gradually increases and it is maximum in the area of 20 to 30 degree and then gradually it reduces towards the periphery And towards that nasal retina, what is happening? The density of the rod cells increases and there is no, as we mentioned, in the blind spot region, there is no rod cells or cone cells; after that, again the density increases, increasing and gradually it is reducing So, the density of the cone cells is maximum at the 0 degree or 1 to 2 degree of the foveal area So, at the fovea; 1 to 2 degree within this zone the concentration or density of the cone cell is maximum, and there is no rod cells Then, from that centre point if we move towards the periphery; in both the direction, the density of the cone cells reduces but in case of rod cell; what is happening? The density is maximum within the area of 20 degree, from the center point of fovea So, both the sides; 20 to 30 degree; the density of the rod cell is maximum, then it gradually reduces So, due to this type of distribution of rod and cone cells, visual acuity also differs So, visual acuity is maximum within this zone, in this image, it is shown field of view eccentricity from the fovea So, if we consider, this is a foveal region; from the fovea if we go two degree both sides; within this region, the visual acuity is the maximum So, visual acuity within the 2-degree angle of fovea, it is maximum, that is 1; visual acuity Then, from 2 degree to 20 degree; within this zone, the visual acuity, where there is also; there is concentration of rod cells are increasing and that is the maximum, within this zone, as we mentioned So, that region, it has the visual acuity of 0.3 After that, from 25 to 45 or beyond that, it is drastically reducing, it is 0.1 So, maximum visual acuity is possible in the center point of the fovea, and gradually,

it is reducing towards the periphery So, visual acuity; maximum at the fovea centralis, and then reducing gradually, as I mentioned So, 0.3 from 2 to 20-degree angle and from; after that, it is only 0.1 Now, if an image on the retina is perfectly stationary, means, if eye is not moving for over a second, then what happens? The image gradually fades away, as mentioned by Yarbus (1967) So, for that purpose, human eyes always move little bit and rapid fixation happens This small size rapid fixation is actually; we call it dwell or fixate on a visual detail for about 200 to 300 milliseconds So, always, while we are fixing at a particular point, but our eyes gradually moves, and makes very small fixations, which is known as dwells for the duration of 200 to 300 millisecond and then eyes move a very rapidly; microsaccades happens So, this type of dwell movement for the duration of 200 to 300 millisecond actually helps in refreshing the visual image, otherwise that image will be faded away Movement speed of the eye between fixation is very fast So, from one point to another point, when eye is; eye fixation is happening, then eye movement happens at a very fast speed So, from about 200 degree per second for 5-degree eye movement When, there is requirement of 5-degree eye movement, then, eye movement speed is 200 degree per second On the other hand, when there is movement of 20-degree eye movement, then eye movement speed is 450 degree per second About 5 to 20-degree eye movement take place within the time frame of 20 to 70 millisecond So, for 5-degree eye movement, have, it takes time 40 millisecond; on the other hand, 20 degree eye movement takes the time 70 millisecond Now, on the retina, as we mentioned, in the foveal area, there is the maximum density of cone cells, there are different types of cone cells, that cone cells helps in colour vision and the sensitivity of the cone cells for different wavelengths of lights are also different So, there are mainly three types of cone cells So, one is; red sensitive cone cells, another is green sensitive cone cells, another is blue sensitive cone cells So, colour vision characteristics and colour perceptions are related to relative sensitivities of these cones of different wavelengths of light If we look at this image So, from starting from 400 nanometer to 700 nanometers, within these wavelengths, there are different areas, where blue cones are got activated; similarly, this is for green cones and similarly, for, this is for red cones So, there, this is the sensitive zone for the blue cone; similarly, for green cones the wavelengths is also different; it is sensitive within this zone, from this point to this point, and for red cones, this is from, the wavelengths varies from this point to this point, and peak sensitivity at this points, and this dotted line showing the wavelength sensitivity for rod cells Now, Grandjean (1988) mentioned three types of human field of view; one is distinct or foveal field This foveal field is the viewing angle of 1-degree foveal area, while the human being is fixing their eyes at a particular point So, there a, that line connecting from the eye to that particular point, that is the line of sight or line of gaze, around that 1- degree foveal area is actually very good for visibility and where very distinct vision is possible, that is called distinct or foveal field So, here it is shown, say, if this is the eye So, this 1-degree angle is actually very sensitive for the vision So, that area is called distinct or foveal field, then from 2 degree to 40 degree, within this view cone, this is called middle or central field of view So, there is, that is also good for visibility but not as good as distinct or foveal field After that, if it is beyond 40 degree, that is called outer or peripheral field So, beyond 40- degree eccentricity angle from the visual axis, this zone is called outer or peripheral field, where visibility or visual acuity is relatively less, only the objects which have some movement is perceived by eye Now, colour perception in the field of view In our field of view, the whole field of view is not equally sensitive for all the colors

The size of the visual field varies on the color, it is largest for yellow and blue and smallest for the green So, if this is the center point, means, this is the foveal; fovea, if we move; left-right or up and down, then with the changes in degree, the, so, this is the location of blind spot So, within the view field, the viewing zone for different colours or sensitivity to different colours within the, our view field, is different So, these are the different area, it is shown So, this area is actually sensitive for red colour, then this one is for green, it is almost 15 degree up-down and so, this is actually shown for the right eye; in case of right eye, so, this is the green sensitivity zone for view field Similarly, this is for red, similarly, this is for blue and these dotted lines showing the yellow sensitive zone So, within the view field, all the points or all the areas is not equally sensitive for different types of color Now, for a driverís license, in most of the states in United States, what are the criteria, we are discussing The minimum visual field requirements; a person with two functional eyes; the field of view – 140 degree horizontal should be there, for getting the license A person with one functional eye; field a view – horizontal should be 105 degree The minimum visual field requirement – uncorrected far visual acuity score of 20 by 40 to qualify for an unrestricted license On the other hand, for restricted license – corrected far visual acuity, corrected far visual acuity is 20 by 50, then that person can qualify for restricted license So, this type of, based on the field of view and visual acuity license are actually issued in United States Now, after discussing various aspects of human field of view or driverís field of view, now, we are moving to a field of view of the driverís; inside and outside of the vehicle Target of the automobile designer is to provide 360-degree field of view to the drivers seated on the driving seat, means, both direct and indirect view, it should be almost 360 degree So, the driver can see all around and can ride the car safely Driverís direct field of view and driverís indirect field of view; driverís direct field of view happens through forward-view, through the windshield Then looking back, through rear-window; side views through the side-windows So, by neck movement as well as eye movement, so, driver can directly visualize the external world through the windshield side-view mirror, side windows and back-side windows Apart from this direct view, there is also indirect views So, for indirect views, the driver can use inside mirror or rear-view mirror, then outside mirror for side-view and using different types of display screen, with the help of camera So, both direct and indirect view field is possible So, while we are discussing about the view field, then in that view field, there is also visual obstruction or obscuration due to presence of different vehicle components or other objects So, visual obstruction or obscuration in the driverís field of view happens by vehicle structure and components such as A pillar, B pillar, C pillar or different types of mirrors particularly rear-view; inside rear-view mirror, side-view mirrors, then instrument panels may also create visual obscuration Steering wheel rim, the upper portion of the steering wheel rim, then hood, then lower edges of the window opening, that is the belt line, and headrest of the backseats So, all these vehicle components may create the obscuration in the view field Now, if we look at this image, assume this is a vehicle under consideration, that is the subject vehicle and this is the position of the driver and around that vehicle, there are other vehicles in right-side and left-side lanes So, this is the vehicle R1 and R2, on the right lane Similarly, this is the L1 and L2, another two vehicles on the left lane and this is a vehicle which is following the ëSí vehicle or subject vehicle So, this is located just behind the subject vehicle Now, how is the visibility of the driver? So, driver at this driving seat, he or she can see direct field through the windshield So, this is the direct field of view through the windshield; forward view

Similarly, this is the area, direct field of view through right-side window; right-side front window Similarly, this is the zone for the direct view through left-side window Now, this portion, while the drivers looking at the side mirror, then he or she can also see directly 70 degree right peripheral field So, during looking at the side-view mirror, then there is also direct visibility of the outside, through the windows, that is actually mentioned as 70-degree peripheral field So, this peripheral field, it is also present on the left-side So, while driver is looking at the left-side side-view mirror, then directly he can see this area, through the side view mirror So, this is mentioned as the peripheral field So, it is also 70 degree So, direct forward-view, this is direct side-view, at the same time, this is direct peripheral view; this is direct peripheral view Apart from this using different types of mirrors; side-view mirror and rear-view mirror So, using this right-side side-view mirror, drivers can see this area By the help of right-side mirror, he can see, this zone Using the rear-view mirror, inside rear-view mirror, this zone is visible to the driver So, inside mirror field; this is the left mirror field, and this is the right mirror field So, if we see, so, ultimately almost 360-degree area is visible for the driver Only some portion is obscured by A pillar, B pillar or C pillar So, in this way, by direct visibility or indirect visibility, through different types of mirrors, actually helps the driver to visualize almost 360 degree around that driver during driving So, due to this type of visibility, here you can see, either at least some part of the vehicle is visible to the, suppose R1, this much, this part is visible to the driver Similarly, for L1, this part is visible, through the, whole portion is actually visible through the peripheral field of view So, using peripheral field of view, driver can see L1, similarly, using the peripheral field of view as well as the side-view mirror, he can see, that, these two portion of the R1, R2; it is visible through a rear mirror view field, this vehicle is visible using this inside mirror field and vehicle L2, it is actually visible through the left mirror field So, this is during day condition but in the night condition also; either the headlamp of the following vehicle or the vehicles on the side lanes, otherwise at least the side indicator lamp, the indicator lamp on this side, it is also visible So, due to this type of mirror arrangement; in the day daytime as well as in the night time, at least some part of the vehicle or the vehicle light are visible to the driver, and accordingly he can navigate his vehicle in relation to other vehicles Now, driverís field of view is influenced by various factors; one factor is the characteristics of the driver So, drivers eye location is very important; where drivers eye is positioned? So, it is actually depending on the driverís anthropometry, then accordingly seat adjustment So, drivers eye location has been defined by SAE J standard 941, by the eye ellipse So, eye ellipse, we discussed in our earlier modules, what is eye ellipse So, from the eyellipse we can understand, that how much will be the visibility by the driver Then, visual capability of the driver; visual acuity, accommodation capability, visual contrast threshold So, these factors also affecting the visibility or driverís field of view So, visual acuity gradually reduces with the age, for the older driver due to cataract and other problems there also loss of visual activity On the other hand, with the age, accommodation capability of the lens also reduces, then eye and neck movement is also important for maintaining the field of view Then information processing capabilities of the driver, that is also affecting, then, age of the driver; as we mentioned; with the age visual capability of the driver changes and accordingly it affects the driverís field of view

Apart from driverís characteristics, the characteristics of the vehicles is also influencing the field of vision and field of view So, various aspects of the vehicle design, that is the window-opening dimension, obscuration by vehicle components, like A pillars, B pillars or C pillars, then mirrors, sun-visors, hood, all these components actually creates visual obscuration, then indirect vision devices; mirror, sensors, cameras and displays; those actually also helps in increasing the driverís field of view Then, glares and reflections, these also affects driverís field of view If there is glare or glossy surface; from that, reflected lights are coming to the driverís eye, then there is the visibility problem Then apart from this driverís characteristics as well as vehicles characteristics So, driverís field of view is also influenced by the targeted visuals, what is the size of the targeted visuals? Where it is located? Then photometric characteristics of different targets; for example, road signages, traffic signals, pedestrian, vehicles So, various photo metric characteristics of these objects are also affecting the driverís field of view, then environmental condition; level of illumination, road condition, level of illumination; daylight, during night or it is during the early morning, so, illumination level is different Similarly, road condition is also affecting the, whether, that is crowded road or very empty road ,so, that is also affecting the driverís field of view Then, weather condition, then reflections of interior and exterior sources, that is also affecting driverís field of view So, these are the various factors which influence driverís field of view, within the vehicle as well as outside the vehicle Now we are going to discuss about the up-angle and down- angle from the eye ellipse In SAE J standard 1100; it is mentioned the; how we can define the up-angle, that is A60-1, and down-angle that is the A61-1 So, here So, this is the eye ellipse for the drivers, 95th percentile eye ellipse From that eye ellipse, if we draw horizontal lines and tangent line, from the 5th percentile eye location, above the hood, that point is called above the hood or the lowermost point of the day light opening, that angle is called down-angle So, down-angle is, below the horizon, if we draw one tangent line from the 5th percentile eye location, in the 95th percentile eye ellipse; this tangent line, actually moving like this; above the hood or bonnet This angle, below the horizontal level, that is called or below the straight-forward line, straight ahead line, that is called down-angle This, size of the down-angle actually defines; how much visibility of the drivers with lower body dimension, as I mentioned, 5th percentile eye location, that can be determined Similarly, driver with larger body dimension or taller driver, if their eye location, is at this point, that is the 95th percentile eye point From the 95th percentile eye point, if we draw tangent line upward direction, below the lower edge of the day light opening, down the roof, then this upward angle is called up-angle; this angle is also important for determining the visibility of the taller drivers in upward direction Now, problem with the smaller up-angle; if this upper-angle is smaller, then, what happens? Then taller driver have to duck the head down, during looking at high mounted targets, like traffic-signals, signage, hoardings, banners So, they have to bend forward or they have to duck the neck down to see upward On the other hand, if the size of this down-angle is less, then there is a problem with the drivers with smaller body dimension, means, 5th percentile or lower percentile eye location So, what type of problem they face? Smaller driver have to raise their neck or bend forward during looking at the approaching road over the cowl or hood So, they have to bend forward and they have to see the road So, from this, we can discuss in later slides in details, that if this angle; down-angle is relatively less, then what is happening? Drivers with 5th percentile eye location, they have to move forward or they have to bend forward to see the road over the hood or cowl Now, like rays from the lower part of the instrument cluster

So, if this is the instrument cluster So, from the lower part of the instrument cluster and switches are reflected on the windshield On the dashboard different switches are there, illuminated displays are there, from those, actually lights are reflected on the windshield and then projected on the windshield and then reflected to the eyes of the drivers So, this is the eye ellipse for the 95th percentile eyellipse and as well as the outer one is the So, this is a 95th percentile eyellipse; inner one and outer one is the 99th percentile eyellipse and so, what happens? This illuminated graphics or switches, that, the light from those objects fall on the windshield and reflected to the eyes of the drivers with larger body dimension 95th percentile to 99th percentile So, that is why light rays from the lower part of the instrument cluster and the switches reflected on the windshield and reach to the upper portion of the 95th and 99th percentile eyellipse thus the taller drivers sees the reflected image on the windshield while they are looking at the rear view mirror during night time So, this type of images on the wind shield actually create annoyance or disturbance for the drivers with relatively higher position of the eye in 95th or 99 percentile eye location Now, we will discuss about the visibility problem faced by the smaller drivers So, here, while a driver, assume this is a driver with smaller body dimension, means, 5th percentile or less than that, this type of driver with the shorter or smaller body dimension, they have to move their seat forward to reach the accelerator, brake, clutch as well as the steering wheel So, while they are moving their seat forward, then what type of visibility issues happens? The closest distance at which the driver can see the road, this point, the closest distance is much longer for the shorter driver So, this place, the closest or nearest distance which the driver can see, that point is actually far away from the vehicle, this space is actually known as dead space or blind zone Within this zone, if some objects or say, some animals or kids are there, so, it is almost impossible for the driver to see So, the distance or length of this zone is very large, in case of smaller driver because their downward angle is less or down-angle is relatively less and this line of sight is over the hood, touching the ground at a long distance There is less or no visibility of the front end and the corners of the hood, in case of shorter driver It creates problem; in case of parking, maintaining the lanes, keeping the safe distance from the objects located at the road ahead or the heading vehicle So, they find difficulty, as they cannot see the front edge of the hood or the corners of the hood Then, relatively smaller down-angle; due to the obstruction of forward-view by the top part of the steering wheel rim and instrument cluster So, they have the relatively smaller down-angle and for that purpose, there is also obscuration problem due to the presence of steering wheel rim, instrument cluster binnacle So, all this, actually happens The outside side-view mirrors may obscure the forward field of view The shorter drivers require more neck rotation for direct rear-viewing through rear window and will experience reduced rear visibility problems during reversing or backing up due to higher deck point and taller rear headrests So, driverís with shorter body dimension or relatively low eye height, they find difficulties during reversing the vehicle due to the higher deck point and the taller headrest Driverís side A pillar will create a larger obstruction or obscuration in the forward field of view for smaller drivers, as their sitting position is relatively forward, in comparison to the larger driver Shorter drivers require larger head-turn to view side- view mirrors, due to their more forward sitting position, as compared to the taller drivers or larger drivers Like shorter driverís; taller drivers also find problems in their view field So, taller drivers adjust their seat backward and their eye position is relatively up in the eyellipse The closest distance at which the driver can see the road is much shorter for the taller

driver So, you can see, this blind zone distance is relatively short, in comparison to the shorter driver So, they can see the road very close from the vehicle As the larger driver adjust their seat backward, the tall driver or large driver may have more side visibility problems due to more-forward B pillar obstruction in direct side viewing and more-forward peripheral awareness zones Then, relatively smaller up-angle in case of taller driver may create visibility problems, for external objects placed at higher location, like traffic-signals, signage, hoardings, etcetera The inside rear-view mirrors may obscure the forward direct view Due to more-rearward sitting position, larger or taller drivers have lower indirect field of view; through side or rear-view mirrors Now, obstruction caused by A pillar So, forward, side direct visibility of the driverís; left-side or right-side is actually affected due to the obscuration or obstruction by the A pillars The area of the binocular obstruction is dependent on the cross-sectional width of the A pillar So, how is the size of the A pillar in different position? So, cross-section of the A pillar, then thickness of the rubber sealing So, how much is the rubber sealing thickness? This thickness of the rubber sealing, this black color rubber sealing thickness; this one and at the same time the blackout paint applied to the glass to hide the joints So, all these factors actually create the visual obscuration Now, in their paper Cavatorta (2014), with digital human modeling simulation showed that how this obscuration by the A pillar happens and how it may lead to accident So, distance, when the distance is 6.8 meter, then the person, that, here it is show with the 5th percentile driver, towards the child locator So, for the 5th percentile driver, with a neck angle of 30 degree, the person can see the child beside the A pillar While the distance is 1.9 meter, still that child is visible When the distance is 1.4 meter, then the child is not visible, it is, the child is actually obscured by the position of the A pillar So, this is for, this is the vehicle, and this is the location of the child So, while they are near by only 1.4-meter distance, then actually the location of the child is obscured by the A pillar So, size of the A pillar and its design is very much important to avoid this type of visual obscuration Now, regarding the field of view of the drivers, we are going to discuss about how monocular field of view and binocular field of view differs from each other and accordingly the field of view as well as the obscured zone or zone of obscuration is also different; due to monocular and binocular field of viewing And if we take this case example, where this is the view field for right eye, and this shaded blue zone, it is indicating the obscured area due to the A pillar mirror and the structure of the vehicle Similarly, when the driver is looking using left eye, then for the same A pillar and mirror, the obscured zone will be little bit different and its position is also different So, in that view field, you can see, if we compare these two image, that view field for the right eye and a view field for the left eye is different and accordingly the obscured area for left eye, that is this yellow shaded one and for the right eye, this blue shaded one, that is, these two are different Now, if we super-impose the left eye view with the right eye view, then, how is the overlapping? Now, we can see, this is the view field for the right eye; now, this is the view field for left eye and this middle portion, this is the overlapping zone, means, this is, this obscured area, the blue shaded zone for the right eye and yellow shaded zone for the left eye and this middle portion and this portion of the mirror This is actually obscured, the back side of the area is visually obscured by the A pillar and the mirror; and this is true for both eyes, means, this is a binocular field of

obscure; obscuration zone Although, the monocular field of obscuration zone is relatively larger in size but while there is binocular field of view, means, we are looking through both eyes, then the obscured zone area reduces So, only this portion is obscured by binocular zone So, this portion will not be visible, backside of this area will be visually obscured Similarly, the field of view through the mirror is also different for left eye and right eye So, this yellow shaded area, this is for the left eye mirror-view and this blue shaded area this is the view field through right eye But while we are using both the eyes, means, the combination of left eye and right eye, then the ambinocular field of view through the mirror is relatively larger, that is a combination of these two zones Now, we are moving to the next slide, in this slide, we are going to discuss, how the visual obscuration by A pillar; left side and right side, affecting the visibility of the driver and how that may lead to accident or near to accident So, in this image, we are showing obstruction by the left and right A pillars during left turning at an intersection and in this another image, we are showing, while the vehicle is taking the right turn, then due to visual obscuration by the A pillar, how is the chance of accident? Now, if we look at this particular image, then you can see, while that vehicle is approaching forward and taking a left turn, then what is happening? Due to A pillar, this left-side A pillar, this zone, this particular zone, is actually not visible for the driver; similarly, for the right A pillar, this zone will not be visible So, due to presence of these; both A pillar; left side and right side, these two areas are not visible to the driver, at this particular moment Then, while the driver is proceeding forward, then, what will happen? And taking a left turn, then this vehicle, as this vehicle is not visible, and this vehicle is moving in this direction and another pedestrian, she is trying to cross the road, then there is chance of accident because at this particular moment, the driver inside this vehicle is unable to visualize, this particular, this vehicle as well as the pedestrian Similarly, in the second image, while this vehicle is approaching forward, due to A pillar this zone is not visible to the driver, means, this is the obscured area When that particular vehicle is moving forward and taking a right turn, then what is happening? Due to the right-side A pillar, this zone is actually obscured zone, visually obscured Then, if any of the vehicle or any pedestrian comes from that side, then at that particular moment, the driver from the vehicle will not be able to visualize, and while that driver is navigating the vehicle and going to take a right turn, then there is chance of accident Now, blind zone accidents and how to prevent this type of accident So, for that purpose, there is a published paper by Jacob Bustad in 1995; he mentioned that, how that, a visually obscured zone can be reduced So, for that purpose, we can use different types of mirrors; that inside rear-view mirror as well as side-view mirrors So, in the first image A, it is showing the field of view for the rear-view mirror; inside rear-view mirror So, this is the area, where the driver can see this zone, using the rear-view mirror And if he or she is not using the side-view mirror, then these are the obscuration zone and if any vehicle is present in this two side lanes, it will not be visible to the driver, means, the situation is that, the driver is not using the side-view mirror But while the driver is using both; rear-view mirror as well as the side-view mirror, then what is happening? This is the inside mirror-view, and this is the left mirror-view, and this is the right mirror-view So, this whole zone, is right now visible for the driver, but these two vehicles, in the side lane is not visible to the driver because it is coming within the obscuration zone Now, if we move to the third image; then, if the driver turns the left-side and right-side side mirror in such a way, towards the outside, then the field of view can be changed

And now, the mirror view; mirror field of view, is this one; for the right mirror and similarly for the left mirror; this is the view field; mirror-view field Then what is happening? Actually, now, the obscuration zone; the earlier obscuration zone is divided into smaller parts So, the total obscuration zone has been fragmented in small-small zones; this is 1 zone, 2 zone So, in that way, the obscuration zone is divided into smaller parts and it is actually helping to visualize the drivers, visualize the other vehicles, which vehicles are following this particularly vehicle by the side lanes So, in this way, by using the rear-view mirror as well as the side-view mirrors and their proper adjustment or their proper positioning, we can reduce the obscuration zone created by A pillar, B pillar and C pillar Now, requirement of mirror fields specified by Federal Motor Vehicle Safety Standards So, how much should be the field of view, for the mirror view? Now, while we are positioning the; designers or engineers positioning or designing the mirror, then they have to consider that how much field of visibility should be there, for the particular mirror So, as per the guideline, the driver, driver side; outside-plane mirror; if driver is using the plane mirror, then outside a plane mirror should provide horizontal field of 2.4 meter So, horizontal field of view should be 2.4 meter, and it should cut the distance of 10.7 meter So, from the driverís seating reference point, at a distance of 10.7 meter driver should be able to visualize the road level, this is the level of the road So, from the seating reference point; 10.7-meter distance, the driver, it should not be millimeter, it should be meter So, from the driver seating reference point, at a distance of 10.7 meter, the drivers will be able to see the ground or the road level And at that juncture or at that point, the width of the field of view should be 2.4 meter So, this is the minimum requirement for mirror field Similarly, so, that was for the side-view mirror Similarly, for the rear-view mirror, which is positioned inside the vehicle So, for rear-view mirror; how much should be the field of view? So, minimum field of view should be at least 20-degree horizontal field of view for the rear-view mirror, and it should allow backside of the vehicle, the ground should be visible at a distance less than 61 meter So, in other words, we can say, the inside-plane mirror should provide at least a 20 degree horizontal field, and the vertical field should intersect the ground plane at 61 meter or closer, from the driverís seating reference point to the horizon Now, field of view through mirrors and for that purpose, there are different guidelines; that guidelines for inside rear-view mirror locations, how to position that mirror; inside mirror? So, first; the mirror should be placed within the maximum, that is the 95th percentile reach envelope, with full hand grasp, using Society of Automotive Engineers standard J287 procedure The lower edge of the mirror should be located at least 20 millimeter above the 95th percentile driverís eyesight So that; that mirror, lower edge of the mirror should not come within the field of view of the driver, it should be at least 20 millimeter above the driverís eye level Mirror should be placed outside the head-swing area to avoid the a head crash against that mirror, during any accident Now, guidelines for the side-view mirror and its position So, the short driver seated at the front most location on the seat track should not require head-turn angle more than 60 degree, from the forward line of sight So, while a shorter driver positioning his or her seat forward, at that point he or she should not require more than 60-degree head-turn to visualize the side-view mirror or to look at the side-view mirror

To avoid obscuration in the direct field of view at least 95 percent of the drivers, the upper edge of the mirror should be placed at least 20 millimeters below the 5th percentile driverís eye location So, the side-view mirrorís top edge should be 20 millimeters below the eye level of the shorter driver Mirror should allow shorter driver to see a part of his or her vehicle, and a tall driver to aim upward, to reduce the blind area in the adjacent lane Now, from this particular module, what we learnt? So, various topics; we covered in this module, related to view field of the driver So, first; we discussed about human field of view, under that, we mentioned about monocular field of view, ambinocular field of view and binocular field of view Then, they, in this module there was basic understanding of eye anatomy and functionality of its different components Then, eye movement and neck movement; what is the range of movement of eye as well as for neck and how eye and neck move for visualizing any object? Then, we discussed about visual acuity, visual accommodation, refractive power, blind spot, etcetera Driverís direct and indirect field of view, visual obstruction and obscuration zone in the driverís field of view has also been discussed, then we also discussed about visibility problems faced by the smaller driver as well as by the larger or taller driver While larger or taller driver or smaller driver is navigating the vehicle, how is the visibility related issues due to obscuration by various vehicle components as well as due to their sitting position; how much area is actually visible outside the vehicle So, those aspects we discussed Then visual obscuration, particularly by A-pillar; we discussed in detail Then, requirement of mirror fields specified in Federal Motor vehicle safety standard So, these are the various topics which we covered under module 4 Now, these are the references which have been used for this slide preparations So, in different slides, all these references have been used For better understanding of this particular topic related to driverís field of view and obscuration zone, you can go through all these references, you can explore for your better learning Thank you

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