Autodesk 12812-051462-9011 User Guide 3 - Page 2756

Applying image motion blur is a two-step process: 1 Turn on image motion blur for the object you want to blur, using the Object Properties dialog on page 305. You cannot apply both image motion blur and object motion blur to the same object in the same rendering. 2 Before you render, turn on image motion blur in the Default Scanline Renderer rollout on page 6141 of the Render Setup dialog. Tips and Limitations Image motion blur smudges the object by creating a smearing effect, instead of superimposing multiple images the way object motion blur does. It considers camera movement. Image motion blur is applied after scanline rendering is complete. ■ Because image motion blur is applied after rendering, it can't account for object overlap. When blurred objects overlap, blurring doesn't work correctly and there are gaps in the rendering. To fix this problem, render each blurred object separately, to a different layer, and then composite the two layers using the Alpha Compositor in Video Post or another compositing tool. The overlap problem also applies to objects behind an object rendered with raytrace refraction. ■ Image motion blur doesn't work with objects that change topology. This includes NURBS objects that are animated so their tessellation (surface approximation on page 2554) changes. Regular tessellation doesn't change in this way. This also includes Displacement mapping and Optimization. ■ Image motion blur can yield strange results with objects that have a MeshSmooth modifier on page 1532 applied to them. If you see this happening, turn of the MeshSmooth modifier's Keep Faces Convex toggle (in the Settings rollout). This will fix the problem. ■ Image motion blur is not applied to reflections of objects. It is applied only to actual geometry. Glossary | 8011