Hi, everyone!
I’ve already written to the Ornatrix developers and they in turn passed it on to Epic Games, but I decided to create this thread so that everyone who renders hair with a lot of hair and CV-points - know that there is such a bug.
99% I’m sure it’s a bug in Unreal Rendering. As in the same Redshift - all rendered without any issues.
Even checked those Alembic that I export to Unreal. All the same - everything is fine.
In general, the bug is that if we use more than 1 million hairs and more than 10 points - ROOT UV is destroyed, the color becomes random and dull.
Video demonstration of the issue -
TIMING:
0:00 - So, to begin with, I will show you what the bug is in the Unreal Engine.
0:05 - In the project you will find several Groom files that I prepared for the test.
0:30 - For a start, we put 1 million and 10 CV-points into the scene.
0:35 - As you can see, the color is displayed correctly, as intended.
0:42 - But, if we upload 4 million and 10 CV points, we can see how the color has become duller, with some random on strands.
1:10 - Again we upload 4 million and 10 CV points and see that the color of the ROOT UV is broken.
1:19 - Load 1 million with Frizz modifier and ten CV points.We see that the color is saturated and correct.
1:27 - Now upload 4 million and 10 points with Frizz. With the Frizz modifier - you can now notice Random Color everywhere.
1:47 - So now let’s compare what happens. when we increase the number of CVs. We drag 1 million and 10 points and then 1 million with 30 CV. In the end, what we see is that the color gets duller and random strands reappear all over the carpet area.
2:15 - Now let’s upload 4 million 10 points and compare it to 4 million 30 points.
2:27 - As a result, on more CV points - we see that the color is almost gone.
2:40 - I think you have already understood that my task is to render 4 million and 30 points without losing color, it should not be lost.
2:48 - Now let’s talk about another thing I noticed. If we open the Asset - 4 million and 30 CV points and then do decimate - we see that the bug disappears. It turns out that there is no issue in the Asset itself - the issue is the rendering inside Unreal of a large amount of hair and CV-points.
3:11 - And now, of course, I’ll tell you how I exported from Maya and Ornatrix. It’s simple enough - I used the standard settings through the File-Export-Ornatrix Alembic menu.
3:34 - Before each export, increased the hair value from 1 million to 4 million. I exported with and without Detail = 30 points. Also turned Frizz on and off.
If you’ve encountered the same thing, please like and comment =)
Thank you and have a great day
Best regards,
Andrew.