Shadow stains issue when rendering still image

Hello,

I struggle for days now trying to solve a shadow issue when rendering a still image in UE 5.3.2 (on a Macbook Pro M2).

As shown in the image, shadow stains pattern appear on the lower part of my elements.

I looked for everything I thought the problem could be from : UVs, Lightmass, anti alliasing, …

I’m desperate to find what is going on here… does anybody have an idea what I’m doing wrong ?

Thank you in advance !

Anyone…?

that’s normal. that’s just how cascade shadow maps work. you have a small edge sticking out, that does not cast a full shadow. also the buildings are at an angle. so the cascade shadow map will cast angled shadows.

the only way to reduce it is to raise r.Shadow.MaxCSMResolution or use a different shadow method. vsm has higher resolution by design and ray traced shadows eliminate this issue altogether. vsm has a memory cost and raytraced shadows obviously a computation cost.

the other way would be to reduce the edge and use some shader trickery to make it look like an indent.

Hi Glitchered, thanks a lot for your answer !

That makes me feel a bit better to know that it is normal to have such shadows and that I didn’t miss something big here:

I’ll try your different approaches you suggest and it should be better than where I am now :slight_smile:

Thanks again for taking the time to explain the issue here !

Best,