According to the latest commentary:
1)Shading -- we usually assume that light comes from above. This creates a distinct pattern of shadow which can make something appear to either stick out or sink in.
2)Aerial Perspective -- light scattering caused by particles in the air makes distant objects appear bluer and hazier than closer objects. The amount can vary greatly depending on geographical location, weather, and other factors.
3)Linear Perspective -- this is pretty well-known and may be considered an extension of the "comparative experience with similar objects" phenomenon. It just says that physically parallel lines appear to converge in the distance.
4)Texture Gradients -- this is a combination of linear perspective and relative size. On a uniformly textured surface, the density of the texture elements increases and the size decreases as the distance increases. That sounds more complicated than it really is. Look at these pictures.
5)Height in the Plane -- the closer an object is to the "horizon line" in a picture, the further away it appears to be.
6)Motion Parallax -- the strongest example of this is when looking out the window of a car or bus, you can see that the more distant objects move slower relative to the closer objects.
Hm... there might be more. Anyway, no biggie, I just like to be pedantic every now and then.
It is true we judge distance using these means, however, there are several other depth cues that we use, any of which can take precedence over any other depending on circumstances:
1)Shading -- we usually assume that light comes from above. This creates a distinct pattern of shadow which can make something appear to either stick out or sink in.
2)Aerial Perspective -- light scattering caused by particles in the air makes distant objects appear bluer and hazier than closer objects. The amount can vary greatly depending on geographical location, weather, and other factors.
3)Linear Perspective -- this is pretty well-known and may be considered an extension of the "comparative experience with similar objects" phenomenon. It just says that physically parallel lines appear to converge in the distance.
4)Texture Gradients -- this is a combination of linear perspective and relative size. On a uniformly textured surface, the density of the texture elements increases and the size decreases as the distance increases. That sounds more complicated than it really is. Look at these pictures.
5)Height in the Plane -- the closer an object is to the "horizon line" in a picture, the further away it appears to be.
6)Motion Parallax -- the strongest example of this is when looking out the window of a car or bus, you can see that the more distant objects move slower relative to the closer objects.
Hm... there might be more. Anyway, no biggie, I just like to be pedantic every now and then.
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