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Abstract:
The ground plane’s texture gradient is a well-known, perspective depth cue that derives from the fact that, for a uniformly textured surface, texture elements become smaller and more densely arrayed in the visual field with increased in distance e.g. grass on a field or cobble stones on a street. This size / distance relationship also occurs for objects such that objects of equal size occlude an equal amount of texture at their base regardless of their distance from the observer. Texture gradients have been studied primarily as a relative depth cue that specifies the size of one object relative to another. However, more definite relative scaling can be achieved if the size of texture elements is scaled to some known metric. We hypothesized that perceivers use the amount of texture occluded by their own feet to scale the sizes of objects on a textured ground. Using head-mounted displays and a motion capture system, we were able to increase or decrease the apparent size of participants’ visual feet in a virtual environment. We asked participants to verbally estimate the width and height of many objects using meters and centimeters(varying in size at the base). As hypothesized, perceivers’ estimations of the sizes of cylinders were smaller when participants had larger virtual feet and larger when participants had smaller virtual feet. This demonstrates that texture gradient, in combination with the visual self-located body, can be used to estimate the size of objects.
