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Automatic adaptive LOD

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On 3/18/2020 at 7:15 AM, animats said:

SL has a long series of problems in the LOD area. One big one is all the assets with lower LODs created by the terrible mesh reducer in the uploader. The one that generates meshes with holes if pushed too hard. Then, the standard LI formula rewards extremely sparse lowest LODs. The combination of these problems is why you see so many things that show some random triangles at lowest LOD. Makes SL look junky.

"Generate" Need to be removed from the viewer entirely, I don't understand why LL clings to it like this.

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2 hours ago, Kyrah Abattoir said:

"Generate" Need to be removed from the viewer entirely, I don't understand why LL clings to it like this.

Here's something easy to do that might help. The minimum number of triangles for "Generate" should never be less than some number. I'd suggest about 20. The mesh reducer does such an awful job for very small numbers of triangles that it should not be allowed to go there. If you want a smaller value, you have to go make a lowest LOD model in Blender or Maya.

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9 hours ago, animats said:

Here's something easy to do that might help. The minimum number of triangles for "Generate" should never be less than some number. I'd suggest about 20. The mesh reducer does such an awful job for very small numbers of triangles that it should not be allowed to go there. If you want a smaller value, you have to go make a lowest LOD model in Blender or Maya.

Why keep it?

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9 hours ago, Kyrah Abattoir said:

Why keep it?

Why keep what?

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27 minutes ago, Kyrah Abattoir said:

A broken auto lod generation within the SL uploader.

I looked into this last year. Didn't find an off the shelf solution.

  • The really good mesh reducers, like InstaLOD, InstantUV, and Simplygon, are proprietary and expensive. So you can't just put them into LL's viewer or Firestorm. (You can use Simplygon for free if you're willing to give all your content to Microsoft.) Most of them are for best for reducing 10 million triangles to 10,000 triangles, anyway. Not for 10,000 to 10. That's really hard.
  • Quadric mesh optimization, which tries to minimize the volume between the original and reduced meshes is popular, and there are academic implementations. There's one in Unity, and one in Blender They're brittle. If the mesh isn't "watertight", they tend to crash. That approach is volumetric; you have to be able to decide whether a point is inside or outside the object. SL meshes often are not that clean. This approach is more useful in an interactive system where you can fix the mesh.
  • Optimizing fabric is tough. A piece of fabric is a very thin box. If it has a wrinkle, the wrinkle is a depression in one face and a bulge in the other. A mesh optimizer will not be able to flatten that wrinkle properly. If it tries to flatten the bulge, the mesh goes through itself, so the mesh optimizer can't do that. If it tries to flatten the depression, it introduces a big volume error as it bloats a thin sheet. If you run the quadric mesh optimizer in Blender on a fabric object, it pulls in the outer edges of the fabric and makes the sheet smaller, because that's the change which causes the least error volume. Optimizing clothing meshes needs to be done at a level that knows it is dealing with thin sheets. Probably Marvelous Designer.
  • Algorithms which have lots of tuning parameters can do a good job. There are thousands of low-wage employees optimizing game assets with such tools. That's semi-interactive - you pin the edges you don't want moved, mesh reduce, and use tools to indicate which areas can take more reduction. Keep face detail, give up foot detail, that kind of thing.

Maybe someone more into mesh geometry can do better. I just went looking for open source solutions. Didn't find anything you can just drop in.

I'd like to see automated impostor generation. That can be done automatically. I used to have a little "impostor garden" out back of my workshop in Vallone to demo this as a proof of concept. Many people on here saw it.

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12 hours ago, Kyrah Abattoir said:

Why keep it?

It has been implemented because the SL mesh format requires to have LOD models. It's often a good idea to bring in models early in development, to see what works, and what has to be changed. It's also a quick indicator what the land impact will likely be, by playing with the LOD dials in the importer. Then you know for what to aim for, for handmade LODs.
Creating 3 more LOD models, with their materials requirements before you can bring a model in-world, would be quite inconvenient for creators. For that matter GLOD was quite a good choice, because it's extremely fast (and free of course). It was never meant to be used for finished models.

It's also easy enough to create crap LODs in Blender, Max or Maya. I'm pretty sure, if the SL importer wouldn't have the LOD generator built in, the usual suspects would just create what we call "zeroed out" LODs within their editor of choice to abuse land impact.

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12 hours ago, arton Rotaru said:

It has been implemented because the SL mesh format requires to have LOD models. It's often a good idea to bring in models early in development, to see what works, and what has to be changed. It's also a quick indicator what the land impact will likely be, by playing with the LOD dials in the importer. Then you know for what to aim for, for handmade LODs.
Creating 3 more LOD models, with their materials requirements before you can bring a model in-world, would be quite inconvenient for creators. For that matter GLOD was quite a good choice, because it's extremely fast (and free of course). It was never meant to be used for finished models.

It's also easy enough to create crap LODs in Blender, Max or Maya. I'm pretty sure, if the SL importer wouldn't have the LOD generator built in, the usual suspects would just create what we call "zeroed out" LODs within their editor of choice to abuse land impact.

  • Of course bringing meshs early in development can be useful, who the hell do you think you are talking to :P.
  • Creating crap lods isn't hard either (new>cube, match the required number of texturable faces, done!).
  • Crappy mesh generation being the default option in the viewer creates the expectation that "this is what you should do/use", with hand made lods being kind of a "special case".
  • Sure, people would still create crappy lods in the end but there is a huge difference between putting them in a position where they can shift the blame on LL and the uploader, and having them create trash themselves.

 

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7 hours ago, Kyrah Abattoir said:
  • Of course bringing meshs early in development can be useful, who the hell do you think you are talking to :P.
  • Creating crap lods isn't hard either (new>cube, match the required number of texturable faces, done!).
  • Crappy mesh generation being the default option in the viewer creates the expectation that "this is what you should do/use", with hand made lods being kind of a "special case".
  • Sure, people would still create crappy lods in the end but there is a huge difference between putting them in a position where they can shift the blame on LL and the uploader, and having them create trash themselves.

 


Crap LoDs are crap LoDs, doesn't matter who provides the tool to make them. It never came to my mind blaming LL for implementing GLOD, when people just deliberately zeroing out LoDs to reduce Land Impact. If at all, it's LLs land impact calculation that is to blame.

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3 hours ago, arton Rotaru said:

blaming LL for implementing GLOD

What do you mean by "GLOD"? Probably not this global level of detail system. That's for smooth changes in level of detail as you move. SL doesn't have that.

(UE5, though... Waiting for technical details on that.)

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Posted (edited)
5 hours ago, arton Rotaru said:


Crap LoDs are crap LoDs, doesn't matter who provides the tool to make them. It never came to my mind blaming LL for implementing GLOD, when people just deliberately zeroing out LoDs to reduce Land Impact. If at all, it's LLs land impact calculation that is to blame.

Of course but people are used to seeing crap lods around them and just assume it's "the system being old and bad", today someone i know whined that the new version of the fridge they bought "inexplicably" uses more land impact now.

I checked it, and sure enough, the creator made better lods for it, when before it had none.

Edited by Kyrah Abattoir

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19 hours ago, Kyrah Abattoir said:

Of course but people are used to seeing crap lods around them and just assume it's "the system being old and bad", today someone i know whined that the new version of the fridge they bought "inexplicably" uses more land impact now.

I checked it, and sure enough, the creator made bett

Maybe the Arctan project will help with that in the looooong run. When all of a sudden, even the none LoD objects count more. :SwingingFriends:
Big thumbs up for the fridge creator, though. 👍

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Posted (edited)

I have  a simple solution

 

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Edited by Selc
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