Cue
Ariel perspective
Motion parallax
Relative motion
Texture gradients
Shading
Occlusion
                  Notes
?     ?    x   requires adaptation to local conditions
?    x     x requires viewpoint velocity for absolute depth
             x 
?    x     ? There may b e a familiar size effect
      x     ?     Subject to errors
             x  various cues
Text Box: ordinal
ordinal
Text Box: relative
relative
Text Box: absolute
absolute