I’ve been trying to render a CAD model built in Gravity Sketch and imported as an OBJ into blender 2.82. While rendering an image using the cycles engine, a strange checkered patter is appearing where there should be core shadows on the surfaces. Can anyone help me understand what seems to be the issue?
Welcome!
This looks like the result of overlapping faces, like those areas got duplicated. Are there 2 surfaces on top of each other? If you go into edit mode and delete some faces, do you find an other surface in the same space?
Welcome to the community, @mazheru6! And to piggyback on @etn249’s diagnosis, a way to quickly remove duplicate geometry is to “Merge by distance”. Select all your vertices, go to the vertex menu, and choose “Merge by distance”. That will merge any two or more vertices sharing the same (or very similar locations) into a single vertex.
Thank for the feedback! I don’t think it was overlapping faces because there were other spots in the model that rendered with these patchy shadows. I ended up looking for duplicated faces as you said and I didn’t find any. So ultimately I ended up creating a new file and re-imported my model, which worked perfectly!
Thanks for having me in this community! I appreciate the tip. I’ll keep that in mind. I couldn’t find any duplicated geometry when I tried to diagnose why I was having patchy shadows during the rendering process. I ended up just creating a new file all together, and ditching this one…worked perfectly!
If it wasn’t a problem with the geometry, it could also have been a problem with the scene’s clipping distances.
Depending on the scale of the scene, these numbers must be adjusted. The clipping start shouldn’t be smaller than it needs to be and the end shouldn’t be farther than the maximum size of the scene.
Wrong distance numbers will make Blender struggle to display the object’s depth accurately and you get glitches.
There are also similar settings on the camera object for rendering.
I adjusted those as well. I think the issues started when I imported a portion of the CAD and then separated elements of the CAD by material. I ended up hiding the separated element, while it was still linked to the parent data. When I reimported the same element, separate from the rest of the CAD, the two parts must have been overlapping while I was rendering the image out
