Contrast Distortion Artifact

Why do I see distortions in my point cloud at the border of an object or between dark and bright regions?

Contrast distortion is an artifact in the point cloud that appears as a wavy surface that doesn’t exist in the real scene. This ripple-like effect appears when we have an abrupt intensity change in the 2D image (e.g. in a black to white transition on a checkerboard or regions with specular reflections such as on the surface of a shiny metal cylinder). The errors are visible as surface distortion/deformation artifacts in the 3D point cloud, see the image below for illustration.

Note

Contrast distortion only occurs perpendicular to the camera baseline.

How to reduce/remove the artifact?

To reduce/remove contrast distortion, we should first position the camera such that we reduce the highlights in the scene. Then we should tune the Contrast Distortion Filter accordingly to correct and or remove the remaining affected points. For more details, see Dealing with Highlights and Shiny Objects.