I created and textured this in Blender and imported into UE 5.7. I flipped the Normal green channel which fixed some issues but there’s still this weird hashing on the flat faces opposite the light source. It’s there even with the default UE materials applied so I think it’s the mesh itself. Is this a UE issue or do I need to tweak the model somehow?
Hi @bcjhood , from what I’m seeing is that this could be a light map issue or smoothing group. Would it be possible for you to provide further information regarding your problem. I’ll be using that information to try and replicate it on my end so that I can ensure to give you accurate information on what steps to take to fix the issue.
- When you put the asset in the level, while selecting the asset in the level (not the content browser) check the “Details” panel under “Transform” you will find a section that called “Modify”(it is under the “Scale” settings). Is your asset set to “Static” “Stationary” or “Movable”? Each of these options will cast different shadows, they range from Baked Lighting, Cached Dynamic Shadows and fully Dynamic shadows. Each version of the shadows has a tradeoff between visuals and performance.
- Could you please provide an image showing the UVs for the Assets and the lightmaps in the Static Mesh Editor?
To do so select the asset in your Content Browser → Double click it to open the Static Mesh Editor → in the preview window right on top of it you will see “Save”, “Browser”, “Reimport Mesh”, “Collision”, “UV”. Please click on “UV” (most likely you will see 2 UV channels that you can cycle thru) - While staying in the Static Mesh Editor go to the “Details” panel and in the search bar type “Light Map Resolution”, if you change them in ranges of 128, 256, 512, 1024 do you see any difference?
- In blender could you please show me a wireframe or topology view of your asset, also if you can please provide if you are using any smoothing groups
Thanks so much for the help.
- The asset is Moveable. I tried Static and Stationary and it didn’t seem to change anything.
- I tried light map resolutions up to 1024 with no noticeable change
- I used Auto Smoothing in Blender at I think 50deg. Not sure what you mean by smoothing groups. It’s made of two meshes, each one smoothed on its own
- Only two lightmaps, Normal and AO. I had some trouble with these, particularly the Normal
- This is the first project/level/modeling/texturing I’ve ever done so all constructive criticism is welcome
Hi @bcjhood , thank you for the additional information you’ve provided. Just to give you an update on this I am currently trying to replicate your asset on my end to trouble-shoot it as soon as I have it running on my end I’ll reach out with my finding.
Based on the info you’ve provided by referencing the normal bakes and the UVs you have. I can see at least from my first pass that Ngons are not present. I thought there were at 1st but those are actually opening on the UV island where you’ve placed other islands in… glancing at the normal bakes I can see where you may have had some trouble with them (baking round objects it’s a massive pain sometimes 
) but the good news is I can’t see anything that would cause the “hashing” in the shadows.
I’m assuming that this is a “geometry-to-light interaction issue” so this is why I’m trying to replicate the geo on my end to test.
If possible, could you please try to rotate in place the asset in your level and see if the shadows issues change or stay the same.
As in, are we seeing the same “shadow hashing” all around the inner boarder no matter at what angle it is rotated to? (this could give us a clue that the main issue may rest in the light set up) or is it present in certain parts based on the rotated angle (this could let us know if there is a problem with the geometry/UV or bakes in that region) the reason why I am asking this is because this part of the render caught my eye
In the level preview where your asset is located could you frame the asset similar to your original post and cycle thru the views options I marked on the screenshot below. Keep in mind, certain views may show up as all black or all white if a map is not attached to it in the material, this does not mean you did anything wrong. The reason I’m having you do this is to check each map to see if there is any evidence of hashing in your other maps. If you do find evidence of the “hashing” in those views please take a screen shot of it and in what view mode you found them.
Lasty I do not want to waste your time sending you on a wild goose chase. What could also be causing this problem is a Cascade shadows and/or low Shadow resolution in the engine. First let’s try and play around with your scalability setting.
Performance and scalability tools → Viewport Scalability → There you can change the overall settings by selecting the option on the tab shown in the image as “3” or change an individual section, for example the shadows Shown on “4”
If that did not work let’s try enabling “Virtual Shadow Maps” (VSM) in the project settings if you do not have it active yet.
Go to the top menu bar and click Edit → Project Settings → In the search bar type in “Shadow Map Method” → Change the selection to "Virtual Shadow Maps"
If none of these work could you check to see if your project is using “Lumen”? To do so:
in the same windows Project Settings → In the search bar type in “Global Illumination Method” check to see if it’s set to “Lumen” → Additionally Type in “Reflection Method” in the search bar and check to see if it’s also set to “Lumen”
I hope this helps 
When I rotate the asset in game the artifacts go away when they’re facing the light. They tend to show up on the faces on the dark side or in the “twilight” in between.
The only other map is the Base Color which does not have those artifacts.
To see if it was my maps I removed mine and used the default WorldGridMaterial and they’re still present. Harder to see though.
Changing the viewport scalability group to any of the options doesn’t improve anything.
Virtual Shadow Maps is enabled.
It is using Lumen.
I did figure out something else. I was wondering why it only showed on certain faces, and it turns out those edges were marked Sharp in blender when I did the Shade Auto Smooth. Here’s what it looks like in Blender for reference, and the edges that are marked sharp.
So I Shaded Flat in Blender, removed the sharp edges, and reimported. This is the result. The hashes are far less prominent but still there. And obviously it’s not shaded smooth anymore.
Then when I disabled my normal map the artifacts disappeared completely.
I don’t know what to make of all that. Seems like a combination of shading and my Normal? I’m not sure what I need to change. For fun here’s my Blender export settings that I read were best for UE objects.
@bcjhood I think we are starting to get closer to a solution now.
Smoothing Groups: are simply a way to tell the software (render engine, DCC authoring program, etc) whether the edge between two adjoining polygons should look sharp (a hard edge) or smooth (a soft smooth edge) when light hits it.
After experimenting on my end I was able to somewhat replicate your issue on a smaller scale. I am now leaning more towards that the smoothing groups present in your mesh may be causing issues. I believe that is the case since when switching from flat to smooth, we start seeing the shading problem appear. Additionally, when you removed the textures and applied the “WorldGridMaterial” the problem it is still present. One thing to keep in mind when adding the normal map back on it the problem may continue or get worst, this is because your smoothing groups also affect your bakes (at least in my experience) some of that information will transfer over to the bakes so you will need to rebake your maps after you edit the topology/smoothing groups. You may still have that information baked into the maps (when this happens you will see them mostly show up in the normal map, AO, and in some cases the curvature or cavity).
Let’s start with changing the smoothing groups first and using the “WorldGridMaterial” for now to see if we can get rid of the problem before we move on to bakes. Bellow I will attach different versions of the mesh with different smoothing groups/techniques that I was able to apply (note I’m not very familiar with blender so I had to do it in maya but the knowledge should transfer without a problem)
In Engine Renders:
My UVs are very simple, I just layed them out quickly to have something to work with.
Now for the fun part!
Since I’m not familiar to how blender is applying the smooth, we are going to be using the bottom corner example (Support loops).
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Select the edges where you previously applied the sharp edges to and add a very small bevel (support loops)
As you can see they are very small, the moment you zoom out they will barely be visible, If possible ensure to have all of the hard edges selected before applying the bevel that way it is applied to all of the edges instead of one by one. -
Please make the entire mesh smooth, since you have support loops in where you used to have sharp edges the moment you apply the small overall bevel it will give you the look of sharp edges even if the entire mesh is set to a full smooth
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Check your UVs to make sure that they did not break once you added the bevel.
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Import the mesh into the engine and apply the “WorldGridMaterial” to test it without adding any of your bakes or textures to it.
If you have any additional question or if you get stuck in any of the steps please let me know.
Well, that did it. Adding a tiny bevel to the sharp edges fixed it. And I just learned the concept of support edges/loops. I really appreciate you taking all the time doing that because I learned a lot.
@bcjhood , I’m super happy that worked out for you. Thank you for having the patience to go thru those steps. If you come across any other issues I’ll be here in the forums so don’t hesitate to pop on by. I wish you the best with your learning journey, take care!