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Why is the triangle and vertices count all the same?


Lydia Alberti
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I uploaded a small part of the mesh and only this component has this problem where when uploaded the triangle and vertices count are all the same! It's not usually the case but why is it here? Because of this I can't change the LODs - Yes I'm aware I can make my own LODs, but here it's not very important to do that. 

image.png.93f38c6ee7f62e8a5e28770a9b22624c.png

EDIT: Think I fixed it by triangulating the faces in Blender. Can someone explain why SL does this then?

Edited by Lydia Alberti
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4 hours ago, Lydia Alberti said:

I uploaded a small part of the mesh and only this component has this problem where when uploaded the triangle and vertices count are all the same! It's not usually the case but why is it here? Because of this I can't change the LODs - Yes I'm aware I can make my own LODs, but here it's not very important to do that. 

image.png.93f38c6ee7f62e8a5e28770a9b22624c.png

EDIT: Think I fixed it by triangulating the faces in Blender. Can someone explain why SL does this then?

First of all, don't rely on automatically generated LOD models.

Second, I ASSUME it's how they decimate the geometry. You might have had an n-gon somewhere in your model, a large one perhaps, which could have confused their decimation algorithm. That's not a criticism of Linden, it's just that decimating while preserving volume (read: mangling your model as little as possible) is a complicated task to achieve. Even if it does work, the topology usually looks like crap. Goes double for n-gons.

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I haven't seen that "error"  :D for maybe five years, but when I DID see it, it was because I had used the wireframe modifier and I "think" the vertices were too close together for the uploader to differentiate. It also could have been because I failed to unwrap the wireframe area. You didn't post your model so it is pretty difficult to say much more than "something is wrong with your model" == which you likely know.  

Did you assign a material to your mesh and unwrap it?   Honestly, there really isn't enough to go on.  

 

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8 hours ago, Lydia Alberti said:

Yes I'm aware I can make my own LODs, but here it's not very important to do that. 

It really is very important to do that & doesn't take long once you have an idea of how aggressive to be at each LOD.

The auto LOD models are junk. No one likes them. Which pressures people to up their graphics settings so they don't see them & reduces performance.

Even if you just made the medium detail one (dissolve some loops small faces), it would look so much better than autojunk.

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It might be good to note that the OP is NOT asking about making her how LODs. She is asking "why" this happened. 

Doesn't anyone actually READ the posts before responding? Come on people. YOUR ideas of "what is right" may not be that of others.

 

 

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44 minutes ago, Chic Aeon said:

It might be good to note that the OP is NOT asking about making her how LODs. She is asking "why" this happened. 

Doesn't anyone actually READ the posts before responding? Come on people. YOUR ideas of "what is right" may not be that of others.

By the time I replied, the issue was already resolved so all I had was a funny meme.

Besides that, two people (you included) have proposed explanations about what caused it, despite the lack of detail in OP's post. I don't think actually elaborating on the good practices does any harm at this point.

Edited by Wulfie Reanimator
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1 hour ago, Chic Aeon said:

It might be good to note that the OP is NOT asking about making her how LODs. She is asking "why" this happened. 

Doesn't anyone actually READ the posts before responding? Come on people. YOUR ideas of "what is right" may not be that of others.

Sometimes you just get more than you asked for.

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12 hours ago, Lydia Alberti said:

EDIT: Think I fixed it by triangulating the faces in Blender. Can someone explain why SL does this then?

 

2 hours ago, Wulfie Reanimator said:

By the time I replied, the issue was already resolved...

I don't see any proper answer here and while I certianly woudln't recommend anybody to use the autogenerated LoD models (expect fro prototyping and test uploads of course) it is a good question and it's quite obvious when you think about it.

Any dcimation algorithm will always work in steps because it doesn't really aim for a specific number of tris and vertices to keep, it removes the ones that fit certain criteria. Sometimes when you change the threshold a little bit there are lots of tris and/or vertices that fit the new limit and sometimes there are none.

Simple example. Let's say the mesh contains triangles that are 3, 5 and 6 cm big (yes, I know they are two dimensional but I'll keep it as simple as possible here). Say the limit is set to remove all the 3 cm tris. Increase the limit to 4 and nothing happens. Increase it to 5 and suddenly all the 5cm tris are gone and you're left with the big 6 cm ones.

Edited by ChinRey
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1 hour ago, ChinRey said:
4 hours ago, Wulfie Reanimator said:

By the time I replied, the issue was already resolved...

I don't see any proper answer here and while I certainly wouldn't recommend anybody to use the autogenerated LoD models (except for prototyping and test uploads of course) it is a good question and it's quite obvious when you think about it.

By "resolved" I meant the original post before the edited follow-up question. They wanted to know how to fix it, but they got it.

1 hour ago, ChinRey said:

Any decimation algorithm will always work in steps because it doesn't really aim for a specific number of tris and vertices to keep, it removes the ones that fit certain criteria. Sometimes when you change the threshold a little bit there are lots of tris and/or vertices that fit the new limit and sometimes there are none.

Simple example. Let's say the mesh contains triangles that are 3, 5 and 6 cm big (yes, I know they are two dimensional but I'll keep it as simple as possible here). Say the limit is set to remove all the 3 cm tris. Increase the limit to 4 and nothing happens. Increase it to 5 and suddenly all the 5cm tris are gone and you're left with the big 6 cm ones.

Until we know what the original model looked like, or until someone comes up with a reproducible example, everything said so far (by everyone) is just (fairly logical) supposition. We have 5-6 fluent meshers here, but no one has been able to say what specifically causes the LOD generator to become unable to reduce the model any further. Maybe it's ngons, maybe verts are too close together, maybe it's non-unwrapped mesh, maybe it's missing materials, maybe it's triangle size, maybe, maybe, maybe.

Edited by Wulfie Reanimator
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4 minutes ago, Wulfie Reanimator said:

Until we know what the original model looked like, or until someone comes up with a reproducible example, everything said so far (by everyone) is just (fairly logical) supposition. We have 5-6 fluent meshers here, but no one has been able to say what specifically causes the LOD generator to become unable to reduce the model any further. Maybe it's ngons, maybe verts are too close together, maybe it's non-unwrapped mesh, maybe it's missing materials, maybe it's triangle size, maybe, maybe, maybe.

There's also an old bug in the uploader that bites every now and then. I don't remember the details since I haven't seen it in ages but under certain conditions when you are reuploading a file, the uplaoder refuses to go below the tri counts you had the first time you uploaded it.

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Hi, only just seen all these messages and I should've provided a screenshot of the model but yeah the only reason why I only relied on the Auto LOD system was because the part of mesh that had the problem were small cylinders that were duplicated using the particle system - so it wasn't entirely important to make my own LODs. But anyway, here's a screenshot of the mesh. Anyway, I fixed the problem by decimating it - it reduced the poly count by a lot! Initially I triangulated it, but it still wasn't able to get the numbers down all the way, so the LI was still returning something like 35, so I scrapped pre-triangulating it. But now that I've decimated it, it was able to properly upload it and reduce the LI to 1.

image.thumb.png.966e65330cc798a2e9bfb6d5a4d3a120.png

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I rarely use more then 8 (vertical) edges for any pipe or cylindric object in general,, you can even go with 4 for cables and wires, with smooth edge ofc...might help in the future with upload, LODs and overall land impact...

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