Hi Riccardo, I spoke with SolidAngle. Eventhough the problem has nothing to do with Arnold, they helped us to solve the issue. There is a different behavior on Python when using BaseBitmap and MultipassBitmap for multiple renders. We render thousands of elements from the object tree in C4D. When you reuse a BaseBitmap the depth information will be saved for every element. However when you do the same with a MultipassBitmap, it will only store the depth information for the first element. Strangely this does not apply to the beauty image. The solution is simple. We set up a new MultipassBitmap for every render call. In hindsight, we should have initiated a new bitmap even for the BaseBitmap. Thank you for time, David