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LOD question ─ verts vs tris

D

deHavilland

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When I run Simplygon's «reduction pipeline» with TargetTriangleRatio of .5 while the number of tris and faces is actually cut by half, the number of verts may be even higher than the original object had.
The SDK documentation in the LOD chapter always mentions verts in absolute and targeted numbers. Therefore I ask myself, whether such a 'reduction' (of tris and faces, but not of vertices) is any good to use as second LOD (LOD01)?
Any insights?
 
Hello..

What is preferred are Tris or quads. Vertices are just a single (smallest) element of a polygon or face.
 
What 3 dimensional object has only one vertex?
deHavilland said:
tris and faces is actually cut by half, the number of verts may be even higher than the original object had.
Click to expand...
Although a polygonal face might be composed of more vertices than 3, it will never have fewer and simple math informs us that any combination of triangles will never result in more faces than edges. Such polygons are really just constructs of multiple triangles anyway, differing sources argue whether multiple triangles can truly be "coplanar" and altogether it suggests the vertices your algorithm are counting are those of 3 dimensional geometry and not those of polygons, because the answer to the riddle is "a cone."

:wizard:
 
Thanks, but can we ignore the higher math ─ which I do not understand ─ and still come to an answer?;) The MS/Asobo recommendations and their absolute (?) limits, like max 150 verts for the highest LOD, are all in verts. (Unfortunately the target values in Simplygon ─ which has, to my knowledge, been aquired by MS ─ are in triangles.
My question was: if an object after reduction has far less tris and faces, but the same number of verts (or even a higher number), shall I use it or abandon?
I noticed that the Blender reduction modifier works differently, all 3 counts (verts, faces, tris) seem to be reduced in a much more linear fashion.
 
Not going to go into it beyond suggesting you're overthinking it, despite refusing to contemplate multiples of triangles. If you know anything about LOD's you know there are extensive debugging tools and procedures. The SDK gives us guidelines to get us started, so we can learn with hard facts how our LODs are performing.

Debug LODs

docs.flightsimulator.com docs.flightsimulator.com

debug_lod_2.gif


Love how they leave the little driver in there for a bit, heck from 2 miles away trying to land a plane in a crosswind, you might just notice!
 
I don't think anyone going to tell you to abandon anything that you created.

I never heard of Simplygon, but not even Decimate within Blender is not always going to be the best option in cutting down Tris. For instance, a wall of an object is going to have 6 vertices or 2 tris (the bare minimum). Of course, removing the wall is not the answer. In this case, the best option is to remove the normal map which would save a total of 24 vertices or 8 Tris. This doesn't count for windows in the walls. The best way, in some cases, is to recreate them without indentations (having the windows be on the same plane as the wall).

Removing Tris is not always the answer, especially if you want the object to stay somewhat in the shape it is. Decimate, in most cases, will try to remove edge lines to combine vertices which in turn will cut down on the number of Tris.
 
Last edited:
=rk= said:
Love how they leave the little driver in there for a bit, heck from 2 miles away trying to land a plane in a crosswind, you might just notice!
Click to expand...
I would have the Driver be the 1st thing to go.. but that is my opinion LOL! ;)
 
WRT Simplygon: The app's Blender plugin was just updated to support Blender 3.6 ─ though Blender support is officially still called 'beta'. It offers 4 main pipelines (reduction, meshing, aggregation and billboards) with a lot of options, baking with choosable texture size included. But quick and easy to setup and use with the defaults. For low-level users 200 runs per day are FREE. That is for the prize of granting Microsoft the right to use your model for certain marketing uses. For me not a problem. I find the 'meshing' pipeline especially usefull for the last (or last couple) of LODs.
Of course, it depends on the shape of your object. But sailships 'dissolve' into thin lines when I reduce their verts count to 150 with Blender's reduction modifier. With Meshing they keep the necessary volume to be seen many miles away. I used to create low-poly lookalikes using primitives, but now I let meshing do this.
 
Github shows version Release 1.3.2 is the latest release on AsoboStudio/glTF-Blender-IO-MSFS git. That release is for Blender 3.3.
Can you tell me where to get the version for Blender 3.6?
 
deHavilland said:
When I run Simplygon's «reduction pipeline» with TargetTriangleRatio of .5 while the number of tris and faces is actually cut by half, the number of verts may be even higher than the original object had.
Click to expand...
After using Simplygon to generate your LOD(s), for each LOD you need to do Merge by Distance (Default value is fine). And then clear and reapply Custom Split Normals Data.
You're seeing a high vert count because of how Simplygon processes the model. Doing merging will bring it back down. The model will also be triangulated, so the count may not be exactly what you expect, but should be about half.
 
Hi folks. Sad news: with today's Simplygon update a message popped up that the FREE Simplygon is going to be discontinued per March 31th (2024). I assume most devs here use the free version and won't switch to an expensive prof's subscriber version.
So it's back to Blender's Decimate modifier. Which actually isn't that bad either. But I loved Simplygon's Remeshing pipeline for the last LOD requiring <150 tris. I never get the same results with decimate. Are there any alternatives?
 
Thanks Dick! I installed the plugin, but was somewhat disappointed. It seems to be just an automation/batch tool, running the decimate modifier with fixed settings (0.5, 0.25, etc). With my first test object, a simple house, LOD01 came out fine with around 50% tris, but LOD02 to LOD05 were unusable (the roof had disappeared).
I'll work a bit with 'merge by distance'. Still thankful for suggestions...
 
A little disappointed seeing the news this morning as well. I used Simplygon pretty heavily in my workflow from remeshing, to LODs, to material baking. It works really good for baking vertex materials and has saved me a lot of time.
It's definitely not in my budget to shell out $5250/yr for it. I don't even want to pay for 3DS and it's 3x cheaper... lol

I was thinking about starting a thread for alternatives that can be used with Blender, but I haven't had the time to do any research into it this morning.
 
If you make less than $10K/year at it, making other industry related software expenses somewhat of a premium, you can get 3ds Max for approximately one seventeenth that cost of Simplygon.

indie.png


$25.50 US/month is about the same cost as Photoshop and ChatGPT-4, who can say no to that? Actual pros, I suppose, they'd have to..
 
In truth, lots of models from Asobo and Microsoft use only one LOD.
 
I find making seamless LODs strangely satisfying, but there are tons of times where I didn't bother. However I always skimp on textures and will always choose the nastiest resolution I can get away with it.

I was marvelling at how awful a few airports run with the statistics profiler and noticed that none of the commercial aircraft carrier mods have any LODs.

It doesn't matter out to sea of course. I presume it does matter somewhat when there's 1.3gb lurking just off the coast of New York.
 
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