Overview
This article will help you understand why sometimes there is unwanted coated or colorful render result in V-Ray IPR and also how to change it.
Issue
The yellow or white coloring of the rendered result, similar to the one shown below, is usually caused by unsupported materials or maps in V-Ray IPR:
Solution
Convert all native Cinema 4D materials to V-Ray Standard materials by using the Convert Materials Tool that you can find in V-Ray > Tools menu:
After conversion, V-Ray IPR should render correctly:
See also: Convert Materials V-Ray for Cinema 4D documentation page.