Hi @MrBig1991
First make a copy of your project.
In the project look for Engine.ini and open in notepad or notepad++
Look for lines of code that have “Substrate” and change 1 to 0
Save the Engine.ini file and open the project
Good luck!
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Sent you a message with the project link. I also noticed something that might be of interest, the bug completely disappears if you just open up a material editor window and maximize it:
Video
I was curious @SebHillaire, since it seems like substrate experiences inflated memory demands compared to the legacy path, has any consideration/exploration been put into using neural networks to compress closures/closure components? From the papers I’ve read on neural texture compression, it seems like substantial gains have been made for relatively small quality losses. Ultimately user editability is paramount however; I was just curious if NNs were being considered as a tool for substrate?
Thank you.
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Hello @jblackwell ,
This is definitely something we consider in general and that should be investigated.
It is unclear what approach exactly we would go with in order to maintain user control on the result without much lose in quality and at what cost it would come from exactly: it would need to be able to work with lumen, environment lighting, path tracer, and likely other things I forget.
Cooking a material shader would also involve training a neural network so likely a bump of cost. Or maybe neural network can be learned once for all for a given topology. Lots of investigations and fun to be had for that to not be a research paper but ready for production 
Hi,
This is because the top layer slab has its SSS MFP input setup. This means that this layer has absorption/scattering properties. When coating another slab, the absorption of the top layer will attenuate the light transmitted to the bottom layer (in color-dependent fashion).
If we tweak the thickness of that layer like this:
We can create different appearances by increasing the thickness. This is because, as the thickness of the top layer increase, the distance travelled by the light become layer, and the more light get absorbed.
I hope this makes sense and answer your question.
/Charles.
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Thank you for sharing that project. It indeed highlighted a separate issue 
when using Lumen reflection but not Lumen global illumination. Because the postprocess volume of the level has Global Illumination set to None, only the Lumen reflection were enabled. And this was a special path in the engine where Substrate implementation wasn’t correct.
It should be fixed on Main (5.4) soon.
Thanks for taking the time to report the issue and share the repro project!
/Charles.
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Hi, I’m getting this problem where translucent Substrate materials only shows the refracted image based on screen space so it cuts off at the top and bottom, have I done something wrong or just a limitation at the moment? I saw that translucent materials doesn’t show in lumen but is it the same the other way around?
/Best
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Hi,
Translucent Refraction/Distortion, rough or not, are only done in screen space. That is the way this is currently implemented. It is done the same way when Substrate is off also.
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I just noticed on Github that transmittance support was added for translucent shadows. Is this just greyscale transmittance for now, or support for something more like colored translucent shadows?
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I have a suggestion.
Substrate Automotive/ArchViz template or material library. Leather, glass, fabric, wood, wall, etc.
Something similar to the existing Automotive Materials.
Having an extensive library of Substrate materials ready to use would help the community understand, study and improve the diverse possibilities that Substrate has.
The upcoming Engine version 5.4 would be perfect for presenting a template with Substrate materials.
I know that there are already Substrate materials in the Content Examples library, but it is something initial.
Cheers,
Bjørn
5 Likes
@jblackwell Those shadows are only grey scale. I mentioned in a post a while back that we want to improve the shadow feature set, notably make then colored: good we agree!
But we are not going to focus on such new feature before we are out of experimental, probably after production readiness even.
@BjornCogxgoc Agreed! Such things are planned but not going to go out before Substrate is out of experimental.
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Substrate’s thin-film does not appear to work with a material set to Translucent Colored Transmitance with the path tracer.
The same material renders thin-film fine in “lit” mode. So this issue is specifically with the path tracer.
As shown below, using the path tracer both opaque and masked modes work with thin film. Just not the translucent modes.
I realize the path tracer is only “kind of” supported with Substrate. Just wanted to bring it to folks’ attention in case it was not a known issue.
This is with UE 5.3
@BjornCogxgoc for the stripes on the ground with the path tracer, I’m seeing this too. FWIW, these go away if you reduce the size of the plane. Perhaps that points towards a fix?
Thanks @derekflood . As you say the Path Tracer is behind when it comes to feature set implementation of Substrate. I did take a note about those issues.
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@derekflood
I noticed this too.
It’s interesting.
@SebHillaire
I noticed that this bug in Path Trace happens with Substrate activated and deactivated.
I tried to get help on the Lumen thread, but to no avail.
what’s the setup? i ust tried. i got those artefeacts when using an hdri backdrop and a floor with a mirror material. artefacts appear when the backdrop and floor are same level. basicly z-fighting in the path tracer. i lowered the backdrop and it’s gone, but looks weird. i for sure set it up kinda wrong . i don’t like hdris.
I had this problem testing substrate the other day.
I have a kinda frosted glass, translucent with rough… roughness
And I’ve noticed this weird (I want to say) screen space artifact where the glass kinda stops being rough or something.
It looks like that when is in the corner of the screen, on the borders of the image, that’s why I’m assuming is screen-space related.
The blurriness of stuff behind rough glass is based on the depth. Stuff close to glass will be less blurry because the rays haven’t scattered as much. Unless I’m missing something, it just looks like some of the leaves are too close to adequately blur.
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