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...Window, and Far Window) and the three viewing distances (5, 10, and 20 ft). Placement of the scissor jacks under the target panel and the laser guides used to adjust the panel are also shown. Journal of Vision (2010) 10(11):8, 1–19 Legge et al. 4 Downloaded from jov.arvojournals.org on 06/29/2019 with a north-facing window and a daytime view of a featureless gray sky, with the near and far locations intended to represent directional lighting in front of, or behind, the target). Stimulus lighting was documented by high-dynamicrange (HDR) images based on multiple photographs using the method of Debevec and Malik (1997). Photographs were taken with a Nikon D80 digital Camera, with an 18- to 135-mm zoom lens set to 18 mm, and tethered to a laptop computer and Nikon’s Camera Control Pro 2 software. A Minolta CS100 Chroma Meter was used for photometric calibration. Figure 6 shows the image locations from which luminance values were sampled for contrast calculations. Contrast values across boundaries were computed between nearby luminance samples L1 and L2 using the Michelson formula C = (L1 j L2) / (L1 + L2) and are listed in Table 1. Note, for example, that for Overhead lighting and the Black Background, most ...

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...ely to impact low vision performance in ways not apparent in empirical studies done in more controlled settings. The importance of the visual accessibility of environments, particularly ramps and steps, is further emphasized by the large literature showing associations between vision and falls or other accidents in the elderly. For instance, there are associations between reductions in binocularity, contrast sensitivity, acuity, and visual field size and the occurrence of falls and hip fractures in the elderly (Ivers, Cumming, Mitchell, & Attebo, 1998; Klein, Klein, Lee, & Cruickshanks, 1998; Lord & Dayhew, 2001). Poor vision is implicated in falls in specific environments including nursing homes (Rubenstein, Josephson, & Osterweil, 1996) and on stairs (Archea, 1985). Visual impairment is also associated with reduced postural stability which increases the likelihood of falls on uneven surfaces (Ray, Horvat, Croce, Mason, & Wolf, 2008). Our test bed was a sidewalk, built in an indoor classroom (Figure 1). The sidewalk was interrupted at a known transition point by a Step Up, Step Down, Ramp Up, or Ramp Down or was not interrupted but remained Flat (Figure 2). Subjects viewed the transition point from d...

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...contrast strips at the top of stairs. With the exception of Goodrich and Ludt (2003) and Ludt and Goodrich (2002), most of the low-vision research on hazards and obstacles has focused on avoiding contact with obstacles while moving through a cluttered space. The past work on obstacle avoidance has concentrated on the influence of three key measures of visual function: acuity, contrast sensitivity, and visual field. The results have usually shown that acuity level is not very important, contrast sensitivity is somewhat important, and the total extent of the visual field is of major importance (Haymes, Guest, Heyes, & Johnston, 1996; Kuyk, Elliot, & Fuhr, 1998; Long, Rieser, & Hill, 1990; LovieKitchin, Mainstone, Robinson, & Brown, 1990; Marron & Bailey, 1982). As demonstrated by Ludt and Goodrich, safety depends critically on the ability to reliably identify potential hazards from a distance. The visual demands of obstacle recognition at a distance are likely to place greater demands on acuity than is the case for avoiding contact with nearby objects and surfaces. The varied and complex lighting present in real architectural spaces is also likely to impact low vision performance in ways not apparent in empirical studies...

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...th the exception of Goodrich and Ludt (2003) and Ludt and Goodrich (2002), most of the low-vision research on hazards and obstacles has focused on avoiding contact with obstacles while moving through a cluttered space. The past work on obstacle avoidance has concentrated on the influence of three key measures of visual function: acuity, contrast sensitivity, and visual field. The results have usually shown that acuity level is not very important, contrast sensitivity is somewhat important, and the total extent of the visual field is of major importance (Haymes, Guest, Heyes, & Johnston, 1996; Kuyk, Elliot, & Fuhr, 1998; Long, Rieser, & Hill, 1990; LovieKitchin, Mainstone, Robinson, & Brown, 1990; Marron & Bailey, 1982). As demonstrated by Ludt and Goodrich, safety depends critically on the ability to reliably identify potential hazards from a distance. The visual demands of obstacle recognition at a distance are likely to place greater demands on acuity than is the case for avoiding contact with nearby objects and surfaces. The varied and complex lighting present in real architectural spaces is also likely to impact low vision performance in ways not apparent in empirical studies done in more controlled set...

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... on hazards and obstacles has focused on avoiding contact with obstacles while moving through a cluttered space. The past work on obstacle avoidance has concentrated on the influence of three key measures of visual function: acuity, contrast sensitivity, and visual field. The results have usually shown that acuity level is not very important, contrast sensitivity is somewhat important, and the total extent of the visual field is of major importance (Haymes, Guest, Heyes, & Johnston, 1996; Kuyk, Elliot, & Fuhr, 1998; Long, Rieser, & Hill, 1990; LovieKitchin, Mainstone, Robinson, & Brown, 1990; Marron & Bailey, 1982). As demonstrated by Ludt and Goodrich, safety depends critically on the ability to reliably identify potential hazards from a distance. The visual demands of obstacle recognition at a distance are likely to place greater demands on acuity than is the case for avoiding contact with nearby objects and surfaces. The varied and complex lighting present in real architectural spaces is also likely to impact low vision performance in ways not apparent in empirical studies done in more controlled settings. The importance of the visual accessibility of environments, particularly ramps and steps, is fu...

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...s. The varied and complex lighting present in real architectural spaces is also likely to impact low vision performance in ways not apparent in empirical studies done in more controlled settings. The importance of the visual accessibility of environments, particularly ramps and steps, is further emphasized by the large literature showing associations between vision and falls or other accidents in the elderly. For instance, there are associations between reductions in binocularity, contrast sensitivity, acuity, and visual field size and the occurrence of falls and hip fractures in the elderly (Ivers, Cumming, Mitchell, & Attebo, 1998; Klein, Klein, Lee, & Cruickshanks, 1998; Lord & Dayhew, 2001). Poor vision is implicated in falls in specific environments including nursing homes (Rubenstein, Josephson, & Osterweil, 1996) and on stairs (Archea, 1985). Visual impairment is also associated with reduced postural stability which increases the likelihood of falls on uneven surfaces (Ray, Horvat, Croce, Mason, & Wolf, 2008). Our test bed was a sidewalk, built in an indoor classroom (Figure 1). The sidewalk was interrupted at a known transition point by a Step Up, Step Down, Ramp Up, or Ramp Down or was not interrupted but remain...

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... in real architectural spaces is also likely to impact low vision performance in ways not apparent in empirical studies done in more controlled settings. The importance of the visual accessibility of environments, particularly ramps and steps, is further emphasized by the large literature showing associations between vision and falls or other accidents in the elderly. For instance, there are associations between reductions in binocularity, contrast sensitivity, acuity, and visual field size and the occurrence of falls and hip fractures in the elderly (Ivers, Cumming, Mitchell, & Attebo, 1998; Klein, Klein, Lee, & Cruickshanks, 1998; Lord & Dayhew, 2001). Poor vision is implicated in falls in specific environments including nursing homes (Rubenstein, Josephson, & Osterweil, 1996) and on stairs (Archea, 1985). Visual impairment is also associated with reduced postural stability which increases the likelihood of falls on uneven surfaces (Ray, Horvat, Croce, Mason, & Wolf, 2008). Our test bed was a sidewalk, built in an indoor classroom (Figure 1). The sidewalk was interrupted at a known transition point by a Step Up, Step Down, Ramp Up, or Ramp Down or was not interrupted but remained Flat (Figure 2). Subjects viewed the t...

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...dents in the elderly. For instance, there are associations between reductions in binocularity, contrast sensitivity, acuity, and visual field size and the occurrence of falls and hip fractures in the elderly (Ivers, Cumming, Mitchell, & Attebo, 1998; Klein, Klein, Lee, & Cruickshanks, 1998; Lord & Dayhew, 2001). Poor vision is implicated in falls in specific environments including nursing homes (Rubenstein, Josephson, & Osterweil, 1996) and on stairs (Archea, 1985). Visual impairment is also associated with reduced postural stability which increases the likelihood of falls on uneven surfaces (Ray, Horvat, Croce, Mason, & Wolf, 2008). Our test bed was a sidewalk, built in an indoor classroom (Figure 1). The sidewalk was interrupted at a known transition point by a Step Up, Step Down, Ramp Up, or Ramp Down or was not interrupted but remained Flat (Figure 2). Subjects viewed the transition point from distances of 5, 10, or 20 ft. They wore blurring goggles that reduced effective acuity to Snellen equivalents of about 20/135 (Single-Blur) or 20/900 (Double-Blur). The subject’s task was to identify the target (5-alternative forced choice). Through introspection, we identified a set of cues useful for distinguishing among the...

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... and Ludt (2003) and Ludt and Goodrich (2002), most of the low-vision research on hazards and obstacles has focused on avoiding contact with obstacles while moving through a cluttered space. The past work on obstacle avoidance has concentrated on the influence of three key measures of visual function: acuity, contrast sensitivity, and visual field. The results have usually shown that acuity level is not very important, contrast sensitivity is somewhat important, and the total extent of the visual field is of major importance (Haymes, Guest, Heyes, & Johnston, 1996; Kuyk, Elliot, & Fuhr, 1998; Long, Rieser, & Hill, 1990; LovieKitchin, Mainstone, Robinson, & Brown, 1990; Marron & Bailey, 1982). As demonstrated by Ludt and Goodrich, safety depends critically on the ability to reliably identify potential hazards from a distance. The visual demands of obstacle recognition at a distance are likely to place greater demands on acuity than is the case for avoiding contact with nearby objects and surfaces. The varied and complex lighting present in real architectural spaces is also likely to impact low vision performance in ways not apparent in empirical studies done in more controlled settings. The importance of the...

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...ings. The importance of the visual accessibility of environments, particularly ramps and steps, is further emphasized by the large literature showing associations between vision and falls or other accidents in the elderly. For instance, there are associations between reductions in binocularity, contrast sensitivity, acuity, and visual field size and the occurrence of falls and hip fractures in the elderly (Ivers, Cumming, Mitchell, & Attebo, 1998; Klein, Klein, Lee, & Cruickshanks, 1998; Lord & Dayhew, 2001). Poor vision is implicated in falls in specific environments including nursing homes (Rubenstein, Josephson, & Osterweil, 1996) and on stairs (Archea, 1985). Visual impairment is also associated with reduced postural stability which increases the likelihood of falls on uneven surfaces (Ray, Horvat, Croce, Mason, & Wolf, 2008). Our test bed was a sidewalk, built in an indoor classroom (Figure 1). The sidewalk was interrupted at a known transition point by a Step Up, Step Down, Ramp Up, or Ramp Down or was not interrupted but remained Flat (Figure 2). Subjects viewed the transition point from distances of 5, 10, or 20 ft. They wore blurring goggles that reduced effective acuity to Snellen equivalents of about 20/135 (S...

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...of mild contrast reduction and glare on face images and everyday sidewalk and driving scenes. Their goal was to simulate the milder visual impairments of the normal aging eye rather than the more severe loss of spatial resolution typical of low vision. They pointed out that it is difficult to imagine or predict the nature of the substantial functional deficits associated with these forms of mild visual impairment. Arditi and Brabyn (2000) have identified some practical measures for enhancing visual accessibility, such as placing high-contrast strips at the top of stairs. With the exception of Goodrich and Ludt (2003) and Ludt and Goodrich (2002), most of the low-vision research on hazards and obstacles has focused on avoiding contact with obstacles while moving through a cluttered space. The past work on obstacle avoidance has concentrated on the influence of three key measures of visual function: acuity, contrast sensitivity, and visual field. The results have usually shown that acuity level is not very important, contrast sensitivity is somewhat important, and the total extent of the visual field is of major importance (Haymes, Guest, Heyes, & Johnston, 1996; Kuyk, Elliot, & Fuhr, 1998; Long, Rieser, & ...

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... under directional lighting might not be seen under diffuse lighting. Brabyn, Schneck, Haegerstrom-Portnoy, and Lott (2004) presented some compelling photos illustrating the effects of mild contrast reduction and glare on face images and everyday sidewalk and driving scenes. Their goal was to simulate the milder visual impairments of the normal aging eye rather than the more severe loss of spatial resolution typical of low vision. They pointed out that it is difficult to imagine or predict the nature of the substantial functional deficits associated with these forms of mild visual impairment. Arditi and Brabyn (2000) have identified some practical measures for enhancing visual accessibility, such as placing high-contrast strips at the top of stairs. With the exception of Goodrich and Ludt (2003) and Ludt and Goodrich (2002), most of the low-vision research on hazards and obstacles has focused on avoiding contact with obstacles while moving through a cluttered space. The past work on obstacle avoidance has concentrated on the influence of three key measures of visual function: acuity, contrast sensitivity, and visual field. The results have usually shown that acuity level is not very important, contrast se...

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...onments, particularly ramps and steps, is further emphasized by the large literature showing associations between vision and falls or other accidents in the elderly. For instance, there are associations between reductions in binocularity, contrast sensitivity, acuity, and visual field size and the occurrence of falls and hip fractures in the elderly (Ivers, Cumming, Mitchell, & Attebo, 1998; Klein, Klein, Lee, & Cruickshanks, 1998; Lord & Dayhew, 2001). Poor vision is implicated in falls in specific environments including nursing homes (Rubenstein, Josephson, & Osterweil, 1996) and on stairs (Archea, 1985). Visual impairment is also associated with reduced postural stability which increases the likelihood of falls on uneven surfaces (Ray, Horvat, Croce, Mason, & Wolf, 2008). Our test bed was a sidewalk, built in an indoor classroom (Figure 1). The sidewalk was interrupted at a known transition point by a Step Up, Step Down, Ramp Up, or Ramp Down or was not interrupted but remained Flat (Figure 2). Subjects viewed the transition point from distances of 5, 10, or 20 ft. They wore blurring goggles that reduced effective acuity to Snellen equivalents of about 20/135 (Single-Blur) or 20/900 (Double-...

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...d glare on face images and everyday sidewalk and driving scenes. Their goal was to simulate the milder visual impairments of the normal aging eye rather than the more severe loss of spatial resolution typical of low vision. They pointed out that it is difficult to imagine or predict the nature of the substantial functional deficits associated with these forms of mild visual impairment. Arditi and Brabyn (2000) have identified some practical measures for enhancing visual accessibility, such as placing high-contrast strips at the top of stairs. With the exception of Goodrich and Ludt (2003) and Ludt and Goodrich (2002), most of the low-vision research on hazards and obstacles has focused on avoiding contact with obstacles while moving through a cluttered space. The past work on obstacle avoidance has concentrated on the influence of three key measures of visual function: acuity, contrast sensitivity, and visual field. The results have usually shown that acuity level is not very important, contrast sensitivity is somewhat important, and the total extent of the visual field is of major importance (Haymes, Guest, Heyes, & Johnston, 1996; Kuyk, Elliot, & Fuhr, 1998; Long, Rieser, & Hill, 1990; LovieKitchin, Mai...