Quote - I tested increasing the min shading rate.

This is a REYES parameter that determines the average area of the micro polygons. I set it to 20, the largest permitted value. This makes them roughly between 4 and 5 pixels across - big enough to see.

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I case you do not know: you can set the shading rate to larger values with Dimension3D's 'Render Firefly'-script that comes with poser.