Mesh LI suddenly doubled

[Kiyoshi Nyoki]

Hello all,

This afternoon, I encountered a nasty problem. I have built a house in Blender, and when I wanted to upload it, the LI was 100 - 110. So I decided to remove all unnecessary vertices and faces, because I figured that less faces mean less triangles, and thus a lower LI. That worked, I managed to upload the house at a cost of 51 LI. Strangely enough, right now, I made some minor adjustments (not increasing the vertex / face count), and decided to upload again. But the house is suddenly 100 - 110 LI again. I am at a loss here... I don't feel like redoing the whole place from scratch, but on the other hand I can't use my uploaded model because I didn't have the UV mapped properly yet. I am using blender 2.62.

Thanks for any input!

Kiyo

[Drongle McMahon]

Did you check the vertex and triangle counts shown in the uploader? One thing that makes a difference is whether your edges are sharp or smooth. At sharp edges, each vertex has to be stored twice (or more), once for each different normal of the faces that share the vertex. This can change the download weight by a factor of two or more. The difference shows up in the displayed vertex count.

Whe you say that the mesh was not properly UV mapped, do you mean not mapped at all? If you upload a model with no UV coordinates, it seems that the uploader uses ununitialised data for the UV map (which can give some surprising texturinf results). Vertices are also stored over again for each different UV coordinate they are associated with. As a result, the random UV maps you get if none is provided can change the download weight by similarly large factors.

Is your house one mesh, or is it made up of lots of small objects (100?). If it is, the land impact can be determined by the server weight of 0.5 per mesh. This doubles to 1.0 per mesh if you add a script.

What about the physics shape? Was the physics shape type, set on the features tab of the edity dialog, the same in both cases? Sometimes switching the shape type can make a large difference.

The first step in working this out is to look at the weight details using the More Info link on the edit diakog, where you can see which weight is varying.

[Kiyoshi Nyoki]

Hello Drongle, thanks for your quick response. The mesh is most sharp, with just a few smooth faces. The problem is that that fact didn't change between this afternoon and now, i.e. between the two uploads. So that doesn't explain the difference. I did mean not UV-mapped at all, indeed. So I might want to check that then, although both times the mesh was uploaded without a UV-map attached to any of the materials. The house is one single mesh. The physics shape hasn't been set yet (I just used the 'default' setting in both cases).

Unfortunately I don't have the old file (I told myself to make new versions with every save, but I forgot... so I can't backtrack). To me it feels like Blender is somehow using the old vertex- and facecounts with the new upload. Don't know if that makes any sense.

I will try setting the UV-maps tho. Perhaps that will solve it. But basically, nothing changed between uploads 1 and 2, except for quitting blender and opening it again, and saving a new export-file over the old one.

[Drongle McMahon]

If it's the UV map problem, that is random. You can get different weights using exactly the same collada file. Your comment about using old settings may point to another possibility. By default the uploader stores a xxxx.sml file in the same directory as the xxxx.dae file the first time the file is used. This is used to fill in many of the fields in the uploader when you reuse that filename. Sometimes changes to the file make that inappropriate and cause various problems. You can override the use of the slm file by deleting it or clicking the reset button in the uploader, or you can eliminate it permanently (as I do) by setting MeshImportUseSLM to FALSE using the Advanced->Show debug settings menu.

[Kiyoshi Nyoki]

And thanks once more I tried uploading with a custom UV map, and I turned off the MeshImportUseLSM setting, but still no luck. I think I am doomed to use the higher LI model for now (we are redeveloping a whole sim, so we have some prims to spare), and try to wrap my mind around where it went wrong later.

[Charlotte Bartlett]

If you haven't done a custom physics upload - what settings are you using - and are you going through the Analyse (setting it to Solid over Surface for a building) steps etc?   Are you then switching from Convex to Prim inworld?

If your model is consistent (ish) it could likely be the physic steps you are following.

[Cel Edman]

I found out, getting your model small/bigger (tested in blender & sl)

 

Merge more objects into 1 object to get the size down. (in blender ctrl-J to merge)

(max 8 textures/materials can be used for 1 object in SL)

 

normals: Smooth objects cost a lot less 'vertices'*; compared to their 'flat' version.

 

UV layout: If your object triangles shares some of the same points in the uv-layout; your number of  'vertices'* also can go down.

 

*(with 'vertices' I mean the number that shows up in the model preview; when uploading your model into sl)

 

[Cel Edman]

While further exploring mesh today, to get the LI down, it can make a huge difference is you use a seperate 'simple' collision model for the physics.

 

I upload my model like normal in the LOD tab;

next I go to the physics tab and choose a seperate model of my build; best just basic cube(s) for collision; Choose one from file.

Step 2: Analyze I select Solid (for like a build with sharp corners/shapes) and press Analyze

Step 3: Simplify I like to choose Retain% then fiddle with Retain: set it to like 10 and press simplify. (fiddle with retain settings higher or lower untill it works for your build)

 

[Medhue Simoni]

If you are using default settings, you are always going to have Land impact variations. The larger the item, the greater the variation. A house is not a small build and generally not a simple build, in relation to the mesh system. At the very least, you have to adjust the settings, as default is never a good choice. LOD choices with large object is EXTREMELY important and can easily send an efficient build to 100 land impact just by 1 LOD setting being totally wrong. How you set your physics is also of major importance as to how high your land impact will be. Simply upload anything with default setting is not a measure of anything except how bad the default setting are.

OH, and i don't mean the defaults are created to be bad. The defaults are bad because every single thing you upload is going to be different and require different setting, depending on what it is.