This might be not laser precision question but this issue appeared a long time ago when first trying to render some scene with 3D models in rasterisation renderer and apply some lighting, posprocessing etc.
Sometimes it look like flooding model area:
But it appears only on models loaded from file, sponza or any other.
So what could be the cause? Numerical errors in shaders?
NaN or negative values? Anyone experiences this?
It's hard to explain because its quite random.