Mesh/Exporting a mesh from Blender

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Basic workflow

Create your model

Some hints:

  1. Take care to create low polygon meshes (as few verts as possible)
  2. Use no more than 8 face textures (8 materials assignments)
  3. Avoid intersecting faces (unless intersections are intended)
  4. Avoid duplicate vertices (unless you want to use the split modifier)
  5. Avoid creating more than 21844 tris per texture face
  6. Avoid creating extremely small polygons (< 0.1 cm edge length)
  7. Did i mention you should create low poly models only ? an avatar with > 10000 faces starts getting too heavy ...
  8. shoes with 30000 polygons per shoe have 20 times too much faces. really!!! Avoid that!
  9. The same is true for hair.
  10. Make low polygon meshes !!!

LOD meshes (with Blender 2.49)

  1. Make sure your blender file is saved
  2. Export your full-detail mesh to COLLADA
  3. Run Poly Reducer with a poly reduce setting of 0.5 (to reduce your polygon count by half).
    • If you make any manual changes to tweak the resulting mesh, remember to update the UV map to match.
  4. Export your mesh to COLLADA; this will be the "medium" level of detail.
  5. Reload your original full-detail mesh. It's good to start from the full-detail mesh each time to prevent errors from accumulating, though this may not be a significant concern for simple meshes such as attachments.
  6. Run Poly Reducer with a poly reduce setting of 0.25 (to reduce your polygon count by three quarters).
  7. Export your mesh to COLLADA; this will be your "low" level of detail.
  8. Reload your original full-detail mesh.
  9. Run Poly Reducer with a poly reduce setting of 0.125 (to reduce your polygon count by seven eighths).
  10. Export your mesh to COLLADA; this will be your "lowest" level of detail. You may also want to use this mesh when defining your model's physics.

Unfortunately the Poly Reducer script is currently only available for version 2.4x of Blender. The "Decimate" modifier is a serviceable substitute but the downside is that you'll need to redo the UV map for each LOD level.

According to:"Poly Reducer issues in Blender 2.71" in blender stackexchange, The UV mapping issues have been solved in recent versions. Decimate Modifier on blender wiki page.

Apply textures

Export to COLLADA

You find the Blender Collada exporter here:

File -> Export -> Collada (Default)

Import to SL

This is a tutorial that was originally made for Avastar (a blender addon) but most of the tutorial also fits to arbitrary mesh imports to second Life. So here it is: <videoflash type="youtube">u575wa3knUM|640|505</videoflash>

Best Practices

Forum thread on optimizing your mesh in Blender for Second Life

Forum thread on installing Blender

Bones and rigging

  • Tool tip: For rigged mesh creation and animation check out Avastar this addon might be of help for you (commercial tool).

Gotchas and workarounds

Optimization techniques

Tutorial links

 ==  Blender 2.5x/2.6x specific ==

Tutorials available in HD

Coffee Cup Tutorials (basics)

Shoe Quest (making a shoe with Blender)

Mesh for sculpted prim creators

Avacademy (basic insights to mesh)

Tip Top Tool tips (medium level tips for blender)

Blender 2.49/2.59 Workflow

Second Life Rigged Clothing Series

SL Mesh Video Tutorial Playlist

How to Use an Offset Pivot Point With SL Mesh

How to Install Blender and Blender Addon Scripts

How to Use the New Bone Weight Copy 2.5x Script

More tutorials (has been updating his tutorials for 2.5)

==  Blender 2.5x SL Mesh Classes ==

Beginner SL Mesh Modeling Series

  • Class Level | Building: Beginner(2) | Blender: Beginner
  • Instructor: Ashasekayi Ra
  • Location: Builder's Brewery Pavilion
  • Time: Saturdays at 10 AM SLT

Blender 2.4x specific (legacy)

Video tutorial BlanderMan rigging tutorial part 1-1, part 1-2, part 2.

Simple tube avatar

<videoflash type="youtube">3JHWDdrIeD0|640|505</videoflash>

Mancandy avatar

<videoflash type="youtube">8w88B7F7v_k|640|505</videoflash>

Scale to meters

Scaling is somewhat arbitrary in Blender 2.49. In principle you just have to know how the mapping is between your 3D program (Blender) and the target environment (Second Life). Then all you need to do is to work in the correct scale. You even can later rescale your model in your target system.

So, what is the issue with Blender 2.49 ? It is all so simple that the Collada Exporter for Blender assumes that one Measurement Unit is mapped to one real life centimeter. But the common expectation in Second Life is that one Measurement Unit is mapped to 1 Second Life Meter. Unfortunately this missmatch very often leads to the import of "tiny objects". The common fix is to scale up the models in Blender 2.49 by a factor of 100.

But there is a nicer fix, which adjust the Collada Exporter to behave according to our expectations. See this video to find out, how you can fix the Measurement missmatch between Blender-2.49b and Second Life once and for ever:

<videoflash type="vimeo">18354783|640|370</videoflash>

If you don't want to watch the entire video:

find the file <blender script dir>\bpymodules\colladaImEx\ and change these two lines: = 'centimeter'
daeAsset.unit.meter = '0.01'

to = 'meter'
daeAsset.unit.meter = '1.00'

To find the scripts directory, do Help > System Information in blender, and look in the text file for "Default dir for scripts:". The path for me is:

C:\Documents and Settings\tapple\Application Data\Blender Foundation\Blender\.blender\scripts

and thus the file is:

C:\Documents and Settings\tapple\Application Data\Blender Foundation\Blender\.blender\scripts\bpymodules\colladaImEx\

Note that this fix is not needed in Blender 2.5x.