On the Shader tab you can select which channels are affected by motion vectors and output vectors.
• Click motion vectors and select the type of vectors you’d like to render:
• off - no motion vector information is rendered.
• velocity - store the velocity of every single pixel in the motion vector channels.
• distance - for every pixel, store the distance (in pixels) between samples in the motion vector channels.
• Adjust motion vector channels to select which channels you want the motion vectors to be output to.
• Check output vectors if you want to render output vectors.
• Select which channels to apply surface points and surface normals from the surface point and surface normal dropdowns.