Black Lighting on Model

Hi guys, not sure if this is the right area to post this in, but I’m getting black areas on my model. Not sure if it’s because I modeled it poorly or what, but I essentially created an arch with several subdivs, bent it, then extruded the faces all the way down and closed the ends off. A big ol’ U shape essentially with several cylinders.

Here’s a picture of what I’m talking about.

aed7d1e7d96c8060607abbb9cc7650128cf18e77.jpeg

How do your UVs look for this model?
Did you any overlapping UVs or degenerated tangents warnings on mesh import?

So I ended up figuring out that I had interpenetrating faces on the inside. which made it spazz out. I’m not quite sure how to do my UV’s since I’m getting some wonky error in Maya when I try to planar project for the bottom of the surface which is a bunch of faces that come to 1 vert. I know n-poles aren’t good practice in modeling, but since no one is going to see the bottom, I figured it was okay but Maya is throwing a fit.

Oohhh… The UV’s AARRREEE messed up… Hhmm… Lemme see if I can fix them.

74aa6dbcb532993304c49c6b8c7f1f995f3a82e0.jpeg

So here are the UV’s in Roadkill.

Here’s the in-engine result with built lighting at High.

Not quite sure what’s still wrong with it. :confused:

What kind of lightmap workflow do you use?
Do you create them by the engine on import, or do you supply a dedicated set of UVs?
Or did you maybe not generate lightmap uvs at all? (The your texture UVs would be used).

Make sure the lightmap coordinate index of the static mesh is pointing to that channel. You can set this in the static mesh details panel.
Although your texture UVs are not overlapping, they might be unsuitable for lightmap purposes due to too close spacing of the UV islands.

Amazing question. I honestly just learned about lightmaps literally /today/. I figured I’d be able to just make my model, then export as FBX, then import and use a default material that Unreal provides to see how my model renders in engine.

From what I understand, lightmaps are a 2nd set of UV’s that have somewhat similar properties that UV’s do, except scaling is OK I think?? I’m not quite sure… Any recommendations as to where I could start learning how lightmaps work and what workflow to use?

Delete all smoothing groups on your mesh, could be a smoothing group issue. Build the light with your new mesh and check if you get the same issues.
You can delete all smoothing groups by selecting all faces in your 3D application of your mesh and simply click in your smotthing groups tool “clear all”…

Second point, leave bigger space between your UV Shells, something like 2 to 4 pixels.

The lightmap UVs are UV coordinates just as any other, but some special “rules” apply:

  • No overlapping. Since they are used to map the lighting (hence the name), overlapping would mean you get the same shadow on two different spots on the object (one of which is naturally incorrect)

  • No inverted faces. For obvious reasons :slight_smile:

  • Padding between islands. Imagine the lightmap as grayscale gradients that are drawn in the UV space and then rendered out at the resolution you specify. Hence higher lightmap resolutions mean higher details, but allocate more memory. the padding is important to have not one UV island being affected by the gradient of the next one. If spaced far enough away, nothing can “bleed over”

  • Create island seams where there is geometry you know that will likely be lit totally different than the rest of the model. One example are the top/bottom faces of wall segments. Since they are liekly to be covered by floor and ceiling elements, they will be rather dark, if not entirely black. Whereas the adjacent wall faces will receive the lighting of the environment. If you have now the wall simply “unfolded”, meaning the floor is conencted to walls UV-wise, then also the dark area will bleed out and you will see dark seams the base of the wall…

HOLY **** GUYS I GOT IT TO WORK I’M SO EXCITED I’M /ACTUALLY LEARNING STUFF/. I honestly ran out of my room and ran down the hallway.

Whew. Okay. Now a slight issue that I’m not TOO concerned about, but why is there a slight seam in my finished product? (The one on the right in case ya can’t tell…)

704f2264b9ca2c795a89b9d14193aaf122a8fc18.jpeg

Hard to see from that perspective, but it appears that the upper part of your model extends outside your LightmassImportance Volume…

Slight seams are common with lightmass, and are typically hidden well enough with textures. There’s some things you can try playing with to avoid them, but I wouldn’t worry about it until everything else in the scene is done.

I think the model is one piece. So no seam should be visible in this case.

OP:

There’s a UV seam, so there can sometimes be lightmass seams.

Huh. Okay! Thanks!!!

Well, my environment will rely pretty much on flat textures, to be honest. I’m trying to model a church with a storta matt white finish on everything for a project that I’m trying to cook up (aren’t we all cooking up something?), so textures aren’t going to be applied in this instance… But how would I go about doing this with textures or any other way you had in mind?

Those are then the seams attributed to bad smoothing groups, as Adik already suggested.