Particle objects blacked out in cycles or evee

[chlowden007]

Hello
I am using a particle system to display objects in a grid in 4.1.1 linux

All looks great in the viewport but when I render I either get objects blacked out …

or with EVEE, not the right objects at all.

Basically anything but what I have in the viewport.

I’ve tried to bake to the scene but I get an error “No valid selected objects”.
GPU & CPU give similar results.
Anyone have an idea how I ca solve this issue please?

[oo_1942 (Kim)]

Objects might be overlapping.
Since the blender does not apply simulation, it is not easy to check even if more than one is duplicated.

Try adjusting the number of particles

[chlowden007]

You’re right. It seems to be an overlapping object issue. But there is more …

In the above screen grab, on the same frame, the viewport and the renderer don’t correspond at all neither in either the object choice or number of instances. In my case , I can live with it but this is not the first time that viewport and renders in particle systems do not correspond. It’s strange …

[oo_1942 (Kim)]

The way to align a certain number of objects without overlap is to put objects in Vertices.

The difference between rendering and viewport occurs when using Children.
I don’t know the other cause of the problem.