Creating Defined Shadows

Hi! I am pretty new with Unreal, and have been going through the documentation to learn the ins and outs.

While playing around with some geometries, I have come across an issue with shadows cast by an object onto the floor. The light source is a directional light above the roof, shining through some fins and casting a grid on the floor. In the pre-build, this appears defined (which is desired), but post-build, it becomes a blob. The shadows of the V-columns also disappears

I have tried increasing the resolution of the lightmap on the floor, as suggested in the unreal documentations, but at 512, it still appears as an undefined blob - and the column shadows are also gone.

Is there some other properties I should be looking into to solve this?

Thank you for your help!!!

Hi Dionysus,

Even though you’ve set a higher LM resolution of 512 it’s still not enough looking at your pictures.

There a few things to keep in mind with assets that need their lightmaps increased.

  • If the object is a large object, like the floor you have here and a single piece of geometry, you will likely need to increase to higher values like 1024 or 2048 to get decent results, and even then it may not be enough due to the size and the quality needed to get higher quality shadows.
  • Break larger objects, even the floor piece, into smaller chunks that can be assembled modularly. You will then be able to use lower lightmap resolutions and get better quality.
  • The layout of the lightmap UV is important here too. If the floor is not using the 0,1 lightmap UV space efficiently by using as much of the space as possible. So for instance, you could have the floor piece only taking up a small portion of the uv space. This doesn’t mean that it will have a 512 resolution. It will have a 512 resolution for the entire space, but since it’s only using a small portion of it will mean that it’s going to be much lower quality than if the uv island for the floor were using more space in the lightmap UV.

I hope that makes sense.

Tim

Just wanted to follow up for future reference! By breaking the floor into units (here at 450cm square planes (rather than solids to maximize the UV square) with resolution lightmap maxed out at 2048, I get shadows that are getting a lot more defined! The smaller I can break down the tiles, the better it will get.

Just wanted to follow up for future reference! By breaking the floor into units (here at 450cm square planes (rather than solids to maximize the UV square) with resolution lightmap maxed out at 2048, I get shadows that are getting a lot more defined! The smaller I can break down the tiles, the better it will get.

Just wanted to follow up for future reference! By breaking the floor into units (here at 450cm square planes (rather than solids to maximize the UV square) with resolution lightmap maxed out at 2048, I get shadows that are getting a lot more defined! The smaller I can break down the tiles, the better it will get.