Normals channel

The Normals channel outputs the orientation of every surface in the image through representing the orientation of its Normal vector at this point. 

This is useful for compositing purposes, i.e. when you need to select all the pixels facing downwards (i.e. to affect them with an aging adjustment), or all of them pointing upwards (i.e. to enhance their brightness). 

Maxwell can output two different Normals channels, depending on the coordinates system you need to consider: 

• World coordinates 
• Camera coordinates 

Normals channel in World coordinates

This mode analyzes each polygon normal vector and represents it in World coordinates, where the polygons aligned towards the X axis appear in red, the polygons aligned towards the Y axis appear in green, and the polygons aligned towards the Z axis appear in blue. 

This information is useful in compositing when you need to perform adjustments dependent on the World orientation of a surface (to mimic dirt, dust, illumination, shadows, etc). 

Normals channel in Camera coordinates

This mode analyzes each polygon normal vector and transforms it to Camera-space coordinates, where the polygons aligned from left to right appear in red, the polygons aligned from down to up appear in green, and the polygons aligned with the camera depth axis appear in blue. 

This information is useful in compositing when you need to perform adjustments dependent on the Camera orientation of a surface (lens effects, etc). 

The render (left) and the Normals channel in Camera coordinates (right)