Big problem - I’m working on a large project and get mesh artefacts everywhere. I don’t get the clean results of Rhino 7. It looks like the parameter ‘max distance’ is ignored.
A quick fix would be very appreciated since it would cause trouble to go back to Rhino 7.
-Micha
Bad meshing WIP8.3dm (400.7 KB)
Had similiar problem in my Rhino 8 WIP.
And here an other example of mesh issues - a large kink is visible. At Rhino 7 it works.
Mesh kink WIP8.3dm (224.3 KB)
Same experience.
There are various regressions in last Rhino 8 I am getting in contact with, unluckily: and this is one of those.
Those mesh settings seem strange…
Max distance edge to surface = 1.0?
Minimum Edge length =1.0
Both of those are very large for the size of the object IMO.
I set the first to 0.01 and the second to 0 and the artifacts went away.
I’m working on a large train interior and need to keep the poly count within limits. Per 1mm smallest detail size I get 56.714.902 total triangular polygons. 1mm is ok, but Rhino should keep this limit. 
At Rhino 7 this kind of setup was great working for years.
Yeah, it looks like the maximum angle setting at least is not being respected. Meshing your object in V7 with the same settings is definitely better.
@John_Brock Who could I ask for a quick fix for the next beta SR release? I need to render high quality renderings at the end of the week and maybe it’s not to difficult to fix.
@Micha
Your best option is reporting it here as you have done.
Is the Mesh kink WIP8.3dm file you posted on 7 April the example?
I’ll see if I can duplicate the problem and get it on the developer’s list.
Is there anything important you can add to help me replicate the issue?
Both examples are useful, the one from the first post shows the large error on curved surfaces the second example the error on flat surfaces.
Using the first file, I’m seeing an not great render mesh in both V7 and V8.
I’ll see if this new file is a better example.
These were my settings back in V4 when I struggled with bad meshing and they seem to do the job now as well:
They work well on curved and double curved surfaces too, light an easy, good for texturing too.
(I just bent your model in two directions)
I changed your Unit Tolerance from 0.00001mm to 0.001mm and using the default meshing settings in V7 and V8, your file looks pretty good to me.
Keep in mind I am not and never was a production Rhino user.
It looks like you combination of overly tight tolerance and custom mesh settings is not a not “good” combination of settings.
WIP8
You fist file looks fine too with the tolerance set to 0.001mm and using default mesh settings:
WIP8
@Holo 's “V4 mesh settings” also produce good looking meshes in V8, and better with the tolerance at 0.001mm.
My model is a large complex train interior with dozen of seats and other details, so I must be careful with the mesh settings and I can’t use the raw default settings. Angle 20° is to raw, aspect ratio is an option which extreme slow down the mesh creation, min edge length 0.0001 is to tight …
My settings should work fine, every parameter is set well thought and should bring the expected result. Angle 8° is great for curved rounds, max length 500 helps to avoid large kinks, max distance edge to surface 1 would be a nice max visual error and smaller details than 1(mm) are not needed. I set the absolute tolerance to 0.01 now, it should be fine for the large train. This kind of setup is logical and was working stable at Rhino 7.
But now at Rhino 8 we see the large kink. The fillet on the screenshot is 2mm and the error is more than twice. At Rhino 7 the max distance edge to surface was good working, I don’t got errors larger than this value. If I set 1 than I got 1 and not 4. I can not use the default setup, it’s ok for simple product shots, but not for large complex models.
Here for example I set the max distance edge to surface to 0 and we get extremely kinks. This are not max angle 8° anymore. The angle limit isn’t kept.
Your setup works because the right 0.1 helps to avoid kinks. But 0.1mm details are to small for a large train interior and I afraid I will get more than 100 millions of polygons. If I set the max error to 1mm than I get this large kink. The chamfer on the edge is 2mm and so I assume the kink error is 5mm. The mesher shouldn’t work so. Complex models need a safe control of the parameters. At Rhino 7 the mesher delivered the ordered values much better.
@John_Brock
If you duplicate the mesh settings shown in his V8 file in V7 and compare, you will see that at those settings V8 is not doing the right thing. The max dist edge to srf is being ignored - there is at least 5mm distance in one spot in V8 - and it looks like the angle tolerance might also be ignored…
Filed as a regression:
https://mcneel.myjetbrains.com/youtrack/issue/RH-74129/Render-mesh-degradation-in-WIP8
The YT item is publicly viewable.
Sounds like @Micha will need to use V7 for this project.
Thanks all
