Which methods provide depth information in 3D vision?

• A. Stereo, structured light, or depth cameras; to compute 3D pose and grasp planning.
• B. Color histogram equalization
• C. 2D edge detection only
• D. Thermal imaging only

Answer: (A)

Depth information in 3D vision comes from sensing how far surfaces are from the camera, so the methods that directly measure or infer distance are the ones that matter for 3D pose and grasp planning. Stereo vision uses two cameras to compare perspectives; the slight shift (disparity) between corresponding points lets us triangulate actual depths. Structured light projects a known pattern onto a scene and analyzes how that pattern is distorted by objects to reconstruct depth map. Depth cameras, such as time-of-flight or integrated structured-light sensors, provide per-pixel depth measurements directly.

Color histogram equalization only changes color appearance without adding geometric information; 2D edge detection finds edges in the image plane but does not recover depth; thermal imaging shows temperature distributions and likewise does not provide depth.