Odd render meshing with some extrusions and certain settings

Got a file from a client who was bewildered by the fact that his file size was huge and he didn’t understand why. I isolated a few of the elements that were causing this and they are in the file below, saved small (no meshes) - only 2.2 Mb for three extrusions. If I use Open to open the file, the render meshes will be regenerated, if you then save it back, you will see that the file size goes up to… 450Mb!!

If you check out the render meshes, they are somewhere between 2 and 4 million polys each… for pretty simple objects. I went looking at the settings that might be causing this - the file when opened has these custom settings:


Which seem kinda normal… Importing (not opening) the file into a blank mm file with Jagged and Faster or Smooth and Slower does not produce the huge meshes. After playing with the settings, it seems like the combination of 15° and ratio 6.0 provokes the problem. Neither one separately seems to cause it.

If you Explode/re-Join the objects or use ConvertExtrusions the problem also goes away… The objects seem “normal”. Anyone know why the meshing settings go so crazy in this case?

TooMuchMemory2-ss.3dm (2.2 MB)


I’ll take a look at this ASAP


Looks like ‘aspect ratio’ is the bad thing in that file.
RH-64087 Mesh: extreme density on extrusion objects

As mentioned above, this file has custom render mesh settings that are on the extremely heavy side. If you run the TestClearCustomMeshSettings command and click the ResetAll option to remove these custom settings, then you get reasonable render meshes.

Somebody and some point explicitly created these custom settings.

Hi Dale,

I’m sorry, but I really can’t agree with your conclusions. The render mesh settings in the file are not in any way, shape or form what I would call ‘extremely heavy’ - I have used variants on this for years and never experienced anything like what’s happening in the file posted above.


If you zoom way in on one of the corners of one of the object’s extracted render mesh, you see this:

There’s nothing in the above settings that should make this happen. The triangles there have a short edge length of only 0.002 and a long edge length of almost 12mm. That’s an aspect ratio of almost 6000 - not 6.0

None of the objects have a custom mesh applied…

Plus, if you re-read the first post, converting the extrusions into polysurfaces without changing the file’s meshing settings makes a MUCH lighter mesh - of the density that I would expect to find with those settings (for example around 110K polys as opposed to 2.7 million).

Certainly, the mesh could be made lighter and still work well, mainly by eliminating the aspect ratio setting, which would bring the 110K polys down to about 3K polys if it’s a polysurface and only about 700 if it stays an extrusion. But that doesn’t explain the problem with the original having 2.7 million.

The aspect ratio setting is clearly at fault here - at least one other poster has had the same experience.

Thanks for all the details and for keeping me honest. I’ll investigate this again later today or tomorrow.

RH-64087 is fixed in the latest Rhino 7 Service Release Candidate