I have a scene where the world angular map is of a seascape. I have a flat plane under a bridge which has two cloud texture maps on it to simulate water movement. But I want only the reflections and shadows that fall on this plane to show. How do I do this? I’m using the Yafray renderer.
You can setup a composite and use the render layers to fetch whatever pass you need.
Click the Render Layers TAB.
You will notice there are a bunch of switches along the bottom of the TAB. Move your mouse over them and wait and a tooltip will popup to show you what each button does. By default, Combined and Z are pressed, but you can unpress them and simply click the Sha button to only get your shadows.
Do a search on RenderLayers or Composite Nodes. there are several threads on this site that covers the subject well.
Can Yafray fetch Blender’s render layer data now?
You may want to render the scene in blender and in yafray then use Blender’s compositor to mask out parts of the yafray render so that you get what you’re looking for. a shadow pass by a factor of the water’s object ID may prove satisfactory. That probably doesn’t help much but it will if you dive into the wiki and release notes on blender.org.