How do you LOD model complex shapes in Blender

The first problem is you can only have up to 29 prims in SL for a vehicle to be physical, aside from attaching prims, which limits details you can do, so I started learning Blender so I could make more complex shapes from one prim.

I've been working on some complex parts for a vehicle trying to make as much from one mesh as I can. Since I am learning Blender, I didn't know about LOD modeling so now I have the problem of losing detail when you are farther away. I already made two sculpties which did not seem to lose detail as you get farther away. One was a gas tank from a sphere and the other, exhaust pipes from a cylinder.

I saw the Machinimatrix video tutorial using the cube example and thought it was only for making a sculpty cube. So now I find you have to LOD model everything to keep the detail. I needed all of the cylinder to create my model. I'm not sure how to LOD model for complex shapes. From what I can gather..you need to go back and forth in multirez from level 3 to level 1 as you are making your model, making sure the main vertices in level 1 do not move when you go to level 3. I can see this most likely limiting the details you can make in a model, becuase as I made my model I need edge rings of the cylinder mesh to be in a specific place. If the level 1 vertices have to be in a certain place that could make the vertices in bewteen useless and limit the detail of the overall model.

So here is my problem. It was recommended not to use multirez, so I didn't. Now if I go back after I have already saved my model and try to use multirez it adds levels to my mesh so I can't reduce it to what it would have been before saving.

Is there a way to rework my meshes to use LOD below 32 x32 or do I have to spend many hours remodeling?

Is there a video tutorial for LOD modelling complex shapes?

There is much to say. Lets keep short

1.) Using Sculpties to save prims is in general not a good idea. It works in special cases, but it doesn't pay back in the general case. At least you have to take care of ...

2.) LOD... Yes, in principle you need to find the right balance between distance independent rendering and freedom of vertex placement. The best way to go would be start modelling in LOD 1, then refine in LOD2-LOD3. If you would only model in LOD1 you would be almost safe regarding LOD invariance. But as you already said, you want to use all vertices, so you MUST prepare for derivations when moving away from your objects.

3.) Complex shapes ... That's where the LOD introduces complications into your sculpter's life. Of course you can position every single vertex wherever you want, but lower LOD levels will then certainly break your model. So as i mentioned earlier i would recommend to use more sculpties to gain more freedom, instead of working against LOD.

4.) Who did recommend you, not to use Multirez ? I am afraid you refer to the machinimatrix texturing tutorial where it says, "if you have multirez turned on, you should turn it off now..." That is meant in the context of texturizing, not in the context of modelling. As long as you do modelling, multirez is definitely your friend.

Concering texturing, i am still not sure about how to work efficiently in LOD1. But i recently started experimenting a bit and i think, texturing can be done even with multirez on, but it gives you less freedom (... aka less faces to texturise on the pro side)

5.) Concerning remodelling, that is realy easy:
- import your sculpted prim (the .tga file) into blender (file -> import second life sculptie). You will get a new sculptie with correct UV-texture AND it will automatically get multirez enabled. From there you can optimize your model for best LOD-invariance and if your model shape does not change a lot, your prepared textures will still be applicable.

One final word: Once you THINK, you are ready with modelling, it makes pretty much sense to store the sculptmap and reimport it into blender (as i explained in 5.) above ) before you import it to Second Life. Then you already can see, how the final sculptie will be different from your blender model And you can possibly do some fine tuning before eventually uploading to SL.

I hope, that helps a bit

You have my sympathy, Layla.
I've hit the same wall a few times. What I'm doing now is using Domino's scripts and working from the starting point of the 8 x 8 face LOD 1 sculpt mesh with the subsurf option to rough out the main critical points for viewing the object from a distance then upping/downing the subsurf modifier levels to see where the extra faces will come in to add the close up detail.
It's very much a to and fro exercise and involves a lot of ctrl/Z to revert to previous steps but it's getting better - all the time!
I'm working on a car and generally end up around the 29/30 components to get it looking reasonable.
Now if only I could get the texturing right!

In the UV editor menu there is an option (with release candidate scripts) "Image - Bake Sculptie LOD"

The brighter the blue dot, the more LODs use that pixel. So you can edit the UV map rather than the mesh to align key edges with the brighter blue dots. You'll lose detail in areas that are shrunk with these edits and gain where the areas grow.

When you have finished editing, bake second life sculptie, and save.

If you import this map, you'll then be able to work on the different multires levels.

With subsurf, you are modeling at the lowest LOD and letting Blender handle the inbetweens (guided by edge creases of course). For some models that's all you need to do as it gives very clean LOD levels. Drinking glasses, vases, columns, petrol tanks, exhausts and cloth are all examples where the subsurf version is probably the final one.

For others you get the rough shape with subsurf, bake and reimport to get a multires version for adding fine detail - things like rock faces where you want more irregularity in the higher LODs.

Sometimes it makes sense to do a different model for texturing and use bake selected to active to get it onto your sculptie. A car grill would be one example where a separate texturing model is probably easier than working directly on the sculptie.

So for one sculptie you might end up with 4 versions. The inital subsurf, the detailed multires, the detailed multires with subsurf (to bake texture to) and a standard mesh for texturing.

The detail work should be minor if you picked a good shape for your sculptie. eg on a car wing, it's probably just the turn light to detail, on a door the handle.. So the majority of the modeling is with the subsurf version and learning which edges to crease to get certain effects is the main way to get LOD friendly sculpties easily. With subsurf you can trust Blender to do the higher LODs and just concentrate on the shape.

If you can't model the shape at 8 x 8, then it's a choice between adding another sculptie to do part of it, or accepting that it won't be LOD friendly. If it's only an extra row or two, then you can use loopcuts to add them. If you add single cuts then their default UV positions match the next LOD level, so it's a good way to get a little extra control without going to full multires.

Gaia,
My impression of the reason for using a scuplty is to be able to make shapes that SL cannot do, as well as making things in far less prims. For example if I make this motor high prim it would most likely exceed 200prims, look very nice, but have to be attached. Using sculpties I can do it in 6 or 7 prims if I can make the parts LOD friendly and save the work I have already done.

In one of our early conversations in IM I think it was you who said you usually have multirez off. I do see you should have it off while making the UV sculpt map.

I have not done any texture mapping yet since I need to make sure my sculpts are going to work right and I still think I do not understand how to do it correctly. The exhaust pipe .blend example you sent me, which you included the texture map you did, I tried to make the texture map and ended up with the same type of problem in the pic I sent you of my exhaust texture UV map. Every texture UV Map I try to make, even following the tutorial does not look anything like the model mesh.

Thank you for the information for re-importing the .tga to be able to rework it. This will same me long hours of remodelling, but I have a feeling it will still take a lot of time and I just may have to start over if I cannot get the detail results I need.

BTW, I am using Domino's scripts and Blender 2.46


Domino,
I cannot seem to find "Image - Bake Sculptie LOD". Maybe I don't have those scripts. Are they part of your sulpty mesh scripts download? Where do I get them if not?

As i said, you can reduce prim count by using sculpties to a certain extent (I have seen a boat which was built out of only 5 sculpties and it looked like it had tens of regular prims) But you will definitely have to fight against LOD. I do not say, it is impossible. I say, it is a challenge!
Maybe i was not clear by then ? I used to work with multirez enabled until i discovered subsurf I use that often now instead of multires (the RC scripts of Domino support both). But at the end it depends on what i am making. If i realy need a "precise sculptie" i often work in the 32*32 mesh and i use a grid of 2.55 in each dimension and i scale the sculptie to these values to get full control of each vertex position. But that is a tidy process and only worth to go in rare situations.

When it comes to texturing, i still prefer to work without multires although as i mentioned there may be ways to better texturing with multirez on (still need experiments)

It will almost never be an exact copy of the model, but it should come close to the model mesh. You can always see derivations from the model due to the roughness of the used grid (256 points in each dimension are not enough for smooth surfaces in general). But you often can compensate roughness by texturing and in many cases (e.g. organic shapes) the roughness is not of a big concern. In your case i am pretty sure, you are fighting against the precision problems. Again i recommend to watch the tutorial "the arch example" which tries to give a workflow for procise sculpting. Not the best though, but it works

Domino refers to his RC scripts, which you can find here:

http://dominodesigns.info/second_life/blender_scripts_git.html

From my current experience, you can replace your scripts with the RC scripts and they still work as you are used to. You might take care of using blender 2.48a... I do not know, if the RC sripts can run on blender-2.46 (but i guess they do)

Hi guys.
Following this thread with interest and have my own questions on the matter.........



OK, first dumb question........ When I bake, export to tga, and reimport as sculpty tga, the item has lost its size properties. Is that normal and I need to redimension by referring to the original model or is there something (else) I'm missing?



Dom, can you enlarge on the 'bake selected to active' you refer to, please. Sounds like a new Blender action I haven't dealt with yet. Also, what is the difference between the third and fourth versions - the detailed multires with subsurf (sounds like something you order in a diner, with fries and mayo ) to bake the texture to and the standard mesh?

If I may refer you to my query in the Texturing forum, (/109/02/298088/1.html) this is where I was beginning to struggle to match the sculpty with the applied texture and achieve a good result.



Does the extra 'row or two' not freak out the sculpty process and have I not grasped the concept fully, or are you talking about the object being totally LOD friendly at all distances?

Drifter

The reimported object is just scaled to the bounding box <1,1,1>. That is similar to what you see when you import to Second Life. You will have to rescale your imported object to get the original dimensions back. If you have the original object still available, just lookup its object properties and transfer the 3 Dimension-values (dim) to your reimported sculptie and your scaling is correct again.

That's normal.



For curves an extra layer or two of subsurf gives smoother results on the texture bake. With bake selected to active, you can bake one objects to another's UV map. This can be useful for normal textures, eg modeling a brick wall then baking it to a plane. It's useful with sculpties as you can ignore the sculptie rules and do a standard mesh just for texturing and then bake it to the sculptie model. If you are just using Blender materials you don't even need to uv map the detail model.



"totally LOD friendly" isn't possible for all shapes. An extra row created with a loop cut lets you model at 8 x 9 faces where the extra row comes from the next LOD level up. It's just a shortcut way to avoid having to handle the whole 16 x 16 LOD level during modeling if you don't need to.

Say rows a0, a1, a2, a3, a4, a5, a6, and a7 represent LOD1 and b0, b1, etc are LOD2.

With the default sculpt mesh you are modeling on all the "a" faces and you loopcut a0. Your mesh is now b0, b1, a1, a2, a3, a4, a5, a6 and a7.

Second Life will still display a0, a1 etc for LOD1, but for modeling, you can just work with enough detail to get the job done.

Layla,

1.) Create your new UV Texture. If you do that in object mode, the new texture will look similar to your Sculptie UV-texture (1024 faces unwrapped to a square). If you do it in edit mode, it may look like a single blue square. But that does not matter at all.

2.) Select your new UV-Texture as "active" and "rendering"

3.) go to edit mode (if you are not already there)

4.) Select all vertices, or only those vertices for which you want to apply a texture.

5.) unwrap as follows:

either do: Mesh -> UV unwrap -> Project Fr0m view (results depend fr0m where you currently see the object, try it, you will understand immediately what happens)

or do: Mesh -> UV unwrap -> unwrap (smart projection)

If you just select "Mesh -> UV unwrap -> unwrap" instead, you get the spikes which you are reporting. If you unwrap with no vertices (aka faces) selected, no unwrap will take place.

I just tested it again with the .blend file i have sent to you. And it works without problems in blender 2.47, 2.48 and 2.48a and it problably also will work in blender 2.46

What can i say more to help you ?

OMG! That's what I kept doing..only Mesh -> UV unwrap -> unwrap. It wasn't clear to me you have to use Mesh -> UV unwrap -> Project From view or Mesh -> UV unwrap -> unwrap (smart projection). Sometimes I'm scared to try something if I don't know what it does, since some of my problems had no undo, so I never tried the other options.

YAY! It works perfectly fine now

I will take some time later to actually do some texturing once I finish the model parts.

Thank you for rescueing me

Thanks, Dom. Yet another aspect of the process to try and absorb! Is the procedure laid out anywhere for numpties to assimilate?
Can I have a new brain for Xmas, please?


Drifter

You may expect something on the machinimatrix-blog by end of this year.

http://www.truveo.com/Tangent-normalmap-baking-in-blender/id/347586393

The basic technique is the same as that. You'd just bake textures or a full render instead of normals and of course the sculptie is already uv mapped, so the low poly unwrap step is not needed.

A brain is a good example of a sculptie that would benefit from this technique.. It lets you model lots of detail that the sculptie could only approximate.

I'd reverse the workflow for this. Do the high detail model first, then use retopo (8x and the shrinkwrap (apply subsurf to get 32 x 32) modifier to shape the sculptie around the brain mesh.

Add a suitable material http://www.blender-materials.org/index.php?action=view&material=262-brain&fc=6 and you should be ready to bake.

So yes you can have a new brain, but you need to make it yourself

Thanks, Dom - bit of a catch 22 there. I can have a new brain but I need a new brain to make it
Gaia - I look forward to anything new you produce on the tutorial front. Great work and just the Xmas pressie I'm after!

Re. my other issue of the sharpness of the texture bake I seem to have a glitch in Blender. I did a test sphere and texture using images from my hard drive, followed Gaia's great tutorial to the letter, and got a stexture map tga coming out at 64 x 64 pixels.
Repeated the thing step by step and this time got the image to come out at the required 1024 x 1024!
So now I've scrapped the existing installation, redownloaded 2.48a and the RC scripts ( also Gaia's Nurbs2Sculpt script to play with when I'm firing on all brain cells). Hopefully that will sort the glitch.
Anyone else experience this odd behaviour of the resolution not matching the bake specification?

OK, now I'll go quiet again and just mumble to myself in a corner trying to absorb the new Blender techniques..............

Sounds like you missed out the step where the new 1024 x 1024 image gets assigned to the UV Faces, or you have the "sculptie" UV layer selected as the render layer. The sculptie map is 64 x 64, so basically it's baking to the wrong image.

Found the glitch - me!
I was blithely assuming that the objects I make keep their associated sculpty map attributes so that when I reopen a blend file I don't need to rebake. Would be nice but doesn't seem to happen for mw unless once again I'm missing something.

Which neatly brings me on to my latest trouble......... I made a sculpty, got the map and everything ok, saved it and even tried in on the Preview Grid, but now when I go back a few days later to start texturing, Blender keeps reporting I can't rebake the sculpty. It still reports as a sculpty mesh (Prim type 7) and Plane (type 3) but it keeps knocking me back reporting a Python error. I was going to cut and paste the console report but found I can't do that in the DOS window.

Short of remaking the sculptie from scratch is there a way I can reassociate the previously made tga sculpty map from elsewhere on my hard drive with the object in the Blend file?

I'll try and stay quiet for a while, honest!

p.s The offending sculpty object is bright dayglo pink when I select texture view while everything else is jet black if that is significant.

In the same way you can load and assign an image to the UVtex layer, you can load and assign the sculptie map to the sculptie uv layer.

If you want to revert a current model to the sculptie map version, then in edit mode you can do Mesh - Scripts - Update from Sculptie and the current mesh will be moved to the sculptie positions according to it's uv map. It will however have a mesh size of 1.0, 1.0, 1.0 so you need to ensure that your object has it's size from scaling and not the mesh. Or just make a note of the sizes and put them back afterwards.

Blender assumes images are temporary unless you tell it otherwise, either by packing the image into the blend file (giftbox icon) or by saving it from the UV Image editor so it becomes a reference to a file.

I already had Domino's scripts in Blender version 2.46. I could not find the option UV Image>Image>Bake Sculptie LOD in the Image options.

I updated to Blender 2.48a and reinstalled Domino's scripts and still do not have the option UV Image>Image>Bake Sculptie LOD. I assume this is after you have made a new UV image and unwrapped>Project From View? There is still no option. I have the options to Add Mesh>Sculpt Mesh, which I have been using all along so I assume the scripts have been working.

Is there another script to install? Am I missing something?

I don't have the Python scripts installed. I went to the link that Blender 2.48a opened and tried to find what I am supposed to install..I can't make heads or tails out it. The download link just takes me to another page.

http://www.python.org/download/releases/2.6.1/.

At the bottom are some options I assume are the downloads..There are four. I have no idea which one I need. I am on Window XP 32 bit and AMD 6000+ processor.

http://dominodesigns.info/second_life/blender_scripts_git.html

It's the release candidate scripts you need for that feature.

Thanks Domino,
I reinstalled the scripts from the site and the option is there now


Now for the bad news..I just tried it and it makes a mess of the sculpt. It is full of spikes, doesn't look anything like it should and the map it's self looks strange with blue squares all over.

Why am I having so many problems?