Compare PEs in single dae upload with in separate daes

[TANAKAAKIO Inshan]

Unexpected PE results bother me again.　
In my case by default, sum of mesh's PEs in single dae upload is much greater than in separate daes upload.
However, seeing prims individually, a mesh's PE in single dae upload are not always greater than in separate daes upload.

It seems that  a whole shape in single dae upload affects PEs of individual meshes.

Even so this doesn't sit well  with me.

 

 

 

Sorry I mistook and delete following　an image　and　some sentence.

 

[Drongle McMahon]

If you used the auto LOD*, then I think your last picture holds the clue. They changed the way the triangle limit works for multi-object scenes. It used to apply the four times reduction separately to each of the components. Now it applies it to the sum of the whole collection. So the reduction for each piece is different. I've no idea how it splits that up. It could br more reduction for bigger pieces, or it could be more for more complex pieces. Plenty of room for experiments here. Will this always mean more PE for multi-object uploads? Or will it sometimes mean less?

I guess if you set triangle limits too?

[TANAKAAKIO Inshan]

Sorry, I mistook and delete a last image and some sentences.

 



[Gaia Clary]

Do you say, that one and the same object can have different PE depending on how it was uploaded ?

[Lilith Heart]

PE results bothers me greatly also and if you have to build in mesh, import the parts separately and then rebuild it in Secondlife, to trick the system to achieve an improvement in PE .... this wrecks the whole point of using mesh in the first place.

One of the beauties of mesh is elegant pipelines that can dramatically improve productivity. If we have to build twice it's not efficient and is unnecessarily creating additional work.

So everyone will have to build everything twice to achieve a bit of an improvement in PE ! that's just bonkers !

Current PE counts for any medium to large objects are absurdly high compared to sculpty equivalents. I'm assuming now that it must be broken and will be fixed otherwise mesh will be unusable for rezzable items

[Drongle McMahon]

Just a hypothesis at the moment. It's not really the PE of "the same object" though, as the different PE would be because of different LOD triangle counts, and we already know that affects PE. I don't generally upload multiple objects  I guess I'll have to do the experiments to test the hypothesis.

[Gaia Clary]

ah, then this happens when you use the automatic generated LODs... and the results depend on the set of imported objects. Well that would make some sense. I have given up on automatic generated LOD a while ago since i realised that making my own LOD's is much better and helps me a lot to reduce PE ;-) So if i use my own LOD-meshes then the PE should not change between uploading them separately or all at once...

BTW the best trick i learned so far (from a feddback on my kettle request article) was to use billborard-like mesh for the lowest LOD. For my kettle this helped to bring streaming cost realy down below 2 and still have a very good look from the distance.

[TANAKAAKIO Inshan]

Upload meshes in single dae or separate daes.

PE changes too much to predict.
A car body wraps parts, it may be reasons.

                 single    sparete
front body           35  >   18
rear body            27  >   14
front bumper          2  <    3
wheel right front     7  >    6
wheel others(7x3)    21  =   21
headlight             2  =    2
right door            5  >    3
left door             5  >    3
front and rear glass  6  >    3
roof                  5  >    2
rear hood             7  >    2
rear bumper           5  <    7
driving parts         2  <    6
steering              2  <    3
seats                13  >    7
meters                6  =    6

================================
sum                 150     106

 

It seems that auto genareted lower level meshes are different depending on how it was uploaded.
Making each LOD mesh is best way to avoid this problem, but it make modeling cumbersome and complicated.
I wonder if decimate modifier of Blender is available for making each LOD mesh.

If PE is greater, the mesh is more detailed. However　it doesn't seem worthwhile to pay about　double　PE in this case.

 

[Drongle McMahon]

"....use billborard-like mesh for the lowest LOD."

Very true. Not only for the lowest LOD only though.  My larger gallery window that uses this technique (radius 3.2) has two meshes, high and low. If I use high-low-low-low it's streaming cost is 0.1, for high-high-low-low it's 0.7, for high-high-high-low it's 2.6 and for high-high-high-high it's 7.3. So you can make very big savings by using the billboard for two or even three of the lowest LODs.

Of course in this case, the 0.1 and 0.7 still come out as 2 PEs because of server weight. :matte-motes-crying:

Andt the physics weight is 0.4 anyway, but in linksets, the advantage would still be there.

[Vivienne Daguerre]

What do you mean by billboard like mesh?

[Drongle McMahon]

For me it means just a small number of flat planes that carry an alpha texture representing the object. I leave Gaia to explain in more detail and correct me if that was not her meaning. I think that a real billboard is a single plane that always points at the camera, like a particle, but we don't have that.

[DanielRavenNest Noe]

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Vivienne Daguerre wrote:

What do you mean by billboard like mesh?

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It means replacing a 3D model of an object with a flat picture of the object on a two triangle flat rectangle.

billboard example

It's called a billboard because it resembles an outdoor advertising sign.  It's also called an alpha plane or sprite sometimes.  You can get away with it at longer view distances because a model of the object and a picture of the object (with transparency for parts) end up looking about the same.

[Vivienne Daguerre]

Thanks for the explanation folks!

[arton Rotaru]

I did billboard like Lowest LODs as well, though in some cases SL don't handle them very well. If I have an extra texture for this Lowest LOD only (another one than what is shown on the other 3 LODs), most of the times the viewer fails to display the lowest LOD quick enough when zooming away from the object. I have to move the cam back and forth, left and right to make the billboard show up. At least this is the case for smaller objects.

[Ashasekayi Ra]

The billboard method can be great for PE. But, if you need to use one with alpha (which is usually the case), you will have to deal with the alpha flickering bug showing up on all the LODs. And, "shiny" won't work with the object any longer because the mesh has a texture with alpha on it.

[Gaia Clary]

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Ashasekayi Ra wrote:

The billboard method can be great for PE. But, if you need to use one with alpha (which is usually the case), you will have to deal with the alpha flickering bug showing up on all the LODs. And, "shiny" won't work with the object any longer because the mesh has a texture with alpha on it.

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You can avoid this by using a separate material for the billboard (If your object has one spare material). Then alpha flickering and the backdraw of having no shiny only affects the billboard LOD.

Also when you only need one image as Billboard (and do not use crossed planes like with trees for example) then there is no Alpha flickering at all. When you have multiple crossing images for the Billboard, then maybe we can use some clever UV-layout trick (like we can do for Sculpties to avoid flicker)...

[Ashasekayi Ra]

Thanks Gaia

I'm going to have to try this today.

[Ashasekayi Ra]

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Gaia Clary wrote:

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Ashasekayi Ra wrote:

The billboard method can be great for PE. But, if you need to use one with alpha (which is usually the case), you will have to deal with the alpha flickering bug showing up on all the LODs. And, "shiny" won't work with the object any longer because the mesh has a texture with alpha on it.

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You can avoid this by using a separate material for the billboard (If your object has one spare material). Then alpha flickering and the backdraw of having no shiny only affects the billboard LOD.

Also when you only need one image as Billboard (and do not use crossed planes like with trees for example) then there is no Alpha flickering at all. When you have multiple crossing images for the Billboard, then maybe we can use some clever UV-layout trick (like we can do for Sculpties to avoid flicker)...

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After making two different material zones, are you also making two different texture maps:  one without alpha and one with alpha?

[arton Rotaru]

I was able to upload a scene of 6 different mesh objects, with custom LODs for each and every part and down to lowest LOD. And with a physics mesh.dae which contains 6 seperate physics shapes. All went fine. Even decomposing the physics shapes worked. Though, 2 mesh objects came out with way higher PE than their single uploaded equivalents.

Then I did a test scene upload with 6 identical cylinders, custom LODs for all, seperate physics shape for each. And I uploaded that cylinder alone. This time the single upload and the scene upload is identical in PE. 

Now I have to figure out why the other scene didn't worked. :matte-motes-impatient:

 

Btw. The upload fee for the 6 mesh scene was 198 L$. Quiet nice compared to uploading 6 times ~160 L$. But if it doesn't work ..... :matte-motes-sour:

[arton Rotaru]

I do so, yes. But keep in mind, currently we have to keep the number of assinged materials in all LODs. So I carry the alpha texture on a single triangle on the other LODs and the non alpha on a single triangle on the lowest LOD.

[arton Rotaru]

I think I found the reason why 2 of my meshes were way higher in PE. I made a mistake when setting up the LOD scenes. :matte-motes-bashful-cute-2: I have put the Low LODs for those 2 in the scene with the Lowest LODs. Now that is corrected, all should work well, though, now my viewer crashes everytime I load the lowest LOD scene.... :matte-motes-mad: 

But I keep trying. :matte-motes-nerdy:

[Ashasekayi Ra]

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arton Rotaru wrote:

I do so, yes. But keep in mind, currently we have to keep the number of assinged materials in all LODs. So I carry the alpha texture on a single triangle on the other LODs and the non alpha on a single triangle on the lowest LOD.

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Thanks Arton. I knew we had to have the same number of material IDs for each LOD (hope they change that later). I just didn't think about using two textures just to get around the alpha issue. I wish they would fix that bug.

[DanielRavenNest Noe]

Its not a bug.  You have one inventory asset with one set of textures associated, and it needs to load the same set of textures at whatever LOD you first see it at.  This would often be the lowest LOD when you are walking around and it comes into draw distance.  The asset server and region server don't know the internal details of the model, so they need to fetch all the textures to make sure you get the ones visible at the initial view distance.

[Ashasekayi Ra]

I know that. I wasn't calling that a bug. The "bug" I was referring to was the issue of alpha flicker on the whole model (ie. higher LODs) when only part of the texture has some transparency. In this case, alpha used for the LOD billboard. Granted, I realize that the LL team has already said this won't change because it isn't a code problem.