I have an issue where converting strands into cards results in very strange tangents. When comparing my model with the MetaHuman, both seem to look very similar when they are strands. But when generating cards, my model get very strange tangents that doesn’t capture the light correctly. When I generate my own cards of the MetaHuman, it looks just fine.
Any tips on what could be causing this issue? Something wrong with the settings when generating, the curves for the hair before exporting to UE, or perhaps the shader itself that needs to be tweaked?
Any article / video regarding Grooms would be appreciated too (though I think I’ve found most of them).
Thanks in advance!
[Attachment Removed]
Hi Avian,
The go-to video tutorial for hair card generation that I am aware of is here, although I suspect that is one you have already found.
Can I clarify your description of the problem - it sounds like you are getting the expected/correct behaviour with the MetaHuman character, but not when using your own model, is that right? Are you able to share a set of steps that we might be able to follow to reproduce the problem, or a few images that demonstrate the differences you are seeing?
Thanks,
Mark.
[Attachment Removed]
Hi Avian,
I’m glad that tutorial was helpful.
Are you able to try increasing the number of cards (and possibly textures) to see if that improves the results?
The attribute sampling (which uses the textures for cards) is done through specialized code in the groom system. So although it looks like the textures aren’t hooked up in the shader through a texture sample op, they are indeed being used. You might be able to see this by removing a single texture from those assigned in the groom cards section. You may also be able to feed the tangents that come out of the groom sampler into diffuse channel to view tangents as color on the groom render.
Beyond that, are you able to provide a more specific set of steps we can use to reproduce the problem, or a sample project?
Thanks,
Mark.
[Attachment Removed]
Hello Mark,
Thank you for the reply and I have actually missed out on some of the videos of your link, so massive thanks for that!
I took the liberty to do some further testing, trying to generate cards from one of the MetaHuman presets (UE version 5.6). It kinda looks like the textures that are generated aren’t being fed into the shader. The image below is what I get off the bat. The first that I see is that the alpha / coverage isn’t right at all.
[Image Removed]
For the sake of troubleshooting, I hard-coded the generated alpha texture straight into the node network, and this makes the alpha look fine.
[Image Removed] [Image Removed]
In this particular card generation, the tangents look correct and seem to be taking the generated texture input. But my previous attempts from yesterday didn’t yield any texture input to the shader at all (no idea how it works now, save for the alpha needed to be hard-coded into the shader)
[Attachment Removed]
Here is a card generation where I removed the alpha so I could show what the textures look like after application
[Image Removed]
[Attachment Removed]