Multi LOD workflow for Blender + Substance Painter?

[Tataku Yugen]

I'm finally getting the comfortable with mesh creation, and have been using Blender with Substance Painter. I want to be a good SL citizen and create appropriate LOD models, but I can't quite wrap my head around a good workflow.

An example of my current workflow (ignoring repeat iterations to correct geometry, UV, etc):

1. Create the model in Blender
2. Bevel edges (manually ctrl-B)
3. UV unwrap
4. Export dae for Second Life and fbx for Painter
5. Import into Painter, bake, texture, paint, etc
6. Export texture, normal map, and specular map

Now if I create a less detailed model (for example, without beveled edges), I would repeat steps 3-6 for that lower LOD. I feel like I'm missing something though. I don't think a bevel modifier would help, since I would presumably still have to apply it before UV unwrapping anyway. I thought about duplicating the geometry before bevelling, but the same thing would apply. And each model would still need to be individually texture/painted.

I guess it boils down to UV unwrapping and painting for each LOD. Is there any getting around this? Or is it just the cost of doing business.

 

[Motoko Oanomochi]

Hello,

I use a 3D software using procedures to create a true model, so I can focus only on design, then I choice the platform and the exporter will make the job, by job I mean create triangles, create LoD or not depends the platform targeted, create the uvmap. Sometime I use Blender, Cinema4D to check the result.

Of course, it is not so easy, but for plenty of tasks that works nicely, of course that needs a lot of time before make the first model, to be honest, but at the end, a lot of time is spared to designers.

Edited September 4, 2019 by Motoko Oanomochi

[Chic Aeon]

4 hours ago, Tataku Yugen said:

 

I guess it boils down to UV unwrapping and painting for each LOD. Is there any getting around this? Or is it just the cost of doing business.

 

 

I work only in Blender so can't really comment on your workflow out to Painter but I am pretty sure you want to keep the SAME UV map and use the SAME texture on all LODs.  It "seems" like just removing your bevel would be a good start for the process.   

 

That being said, you might try making the lower LOD model (like medium) and then unwrap and save that file. Then KEEPING THE SAME UV map, add your bevel. The bevel vertices will appear within the first UV map.     Just don't move any of the original UV map while you are in Substance Painter (assuming that is possible as I have never used it). 

Maybe that will give you some ideas . 

Also if your model is simple enough and you don't have a complex bevel (which you really don't need if you use SMOOTH faces) then the uploader may do a fine job all on its own.   I don't make custom LODs all that often simply because my models are low poly to start with.

 

Good luck and I hope you work it out. TESTING IS REALLY IMPORTANT as you get to the end. Be sure and see how your model looks for folks with LOD 2 and LOD 1.25 etc 

 

[Tataku Yugen]

30 minutes ago, Chic Aeon said:

 

I work only in Blender so can't really comment on your workflow out to Painter but I am pretty sure you want to keep the SAME UV map and use the SAME texture on all LODs.  It "seems" like just removing your bevel would be a good start for the process.   

 

That being said, you might try making the lower LOD model (like medium) and then unwrap and save that file. Then KEEPING THE SAME UV map, add your bevel. The bevel vertices will appear within the first UV map.     Just don't move any of the original UV map while you are in Substance Painter (assuming that is possible as I have never used it). 

Maybe that will give you some ideas . 

Also if your model is simple enough and you don't have a complex bevel (which you really don't need if you use SMOOTH faces) then the uploader may do a fine job all on its own.   I don't make custom LODs all that often simply because my models are low poly to start with.

 

Good luck and I hope you work it out. TESTING IS REALLY IMPORTANT as you get to the end. Be sure and see how your model looks for folks with LOD 2 and LOD 1.25 etc 

 

 

Thanks. I hadn't thought of doing it in reverse like that - starting with lower detail and working my way up. Now I can see a logical workflow.

Substance (as far as I know) doesn't alter the UVs, just exports texture maps. But I'll definitely keep an eye on it. I could swear I saw an option to lock islands in Blender's UV editor. I'll have to investigate that and see if that will help keep them in place when I bevel. 

And I hear you loud and clear on the testing. Aditi is my second home (Third Life?) 

Thanks again!

 

 

[Kyrah Abattoir]

If you don't ever touch your polygons directly during your workflow you are, ultimately, doing it wrong.

Procedurals are a good to work on the design, but after that is nailed you most likely will have to remesh to get something that isn't completely bloated.

For a realtime application, each polygon matters.

My approach is typically to go from high to low.

• Model everything that will be in my final model.
• Write down the triangle count.
• Duplicate the model (this will be my first lod model).
• Remove loops/simplify/collapse until i've reached half or less of the original, that's my first lod (most of those operations won't affect uvs much).
• Write down triangle count.
• Duplicate again and simplify further for my next lod.
• Do it once more, possibly more aggressively for the last lod.

With a bit of practice it doesn't take very long to get something decent.

[Chic Aeon]

18 minutes ago, Kyrah Abattoir said:

If you don't ever touch your polygons directly during your workflow you are, ultimately, doing it wrong.

Procedurals are a good to work on the design, but after that is nailed you most likely will have to remesh to get something that isn't completely bloated.

 

Just wanted to say that there are as many "workflows" as there are people making mesh --- or at least a LOT of different method and no "one" is right or wrong.  

 

I completely disagree with the above statement.  Not everyone is making "render" mesh and then taming it down. Some of course aren't taming it down at all =-=- and that is a completely different problem. 

[Kyrah Abattoir]

I know but i find it strange that @Tataku Yugen feel that he would have to rebuild each lod from scratch and UV them, so maybe I assumed wrong? But i still don't understand why he thought he would have to do that.

Please enlighten me.

[MaxMare]

Before switching to substance, you need 2 models, a regular low/med poly with unbeveled edges (I almost never use bevel for SL) and another model with bevel edges, it can also have more defined geometry, btw bevel aka chamfer, insert loops etc will not mess up your UVs, edges/loops are added/placed automatically to existing maps, the only issue can arise if you later on move mentioned edges in which case UVs should be manually adjusted (I`m a max user so this is how autodesk software works)...ok so substance; save the complex model with _high suffix and the simpler one with _low suffix...once you open substance, import the simple one..The complex  aka high poly model should be added when  you open "bake mesh maps" tab (Bake/Normal/High definition meshes). With your scene set like this, textures are going to be created based on high poly model and applied to low poly model (with beveled edges and generally smoother). That said, you don`t always need 2 models, it is really up to you to decide when it is beneficial and worth the trouble and when not.

Anyways, now you have a decent medium or low poly model with maps that give illusion of more complex geometry...

If you want to create lower LODs, just remove any edges that are not necessary to keep your model base in shape so to speak... The important thing is to keep material count/faces number same and intact or else you won`t be able to upload to SL. So if a certain face is removed you can simply keep one triangle with that particular face number/material and it should work...The lower the LOD the less detail you need, just imagine you are viewing that model from a far and what would be visible, that will help you decide what parts are essential and what can be completely removed for lower LOD models...

When it comes to game asset creation it is generally advised to keep geometry as simple as possible. Tools such as smoothing groups, smooth/hard edges as well as normal baking are of great importance and definitely worth implementing...last but not least, good texturing can transform rather simple meshes in to complex looking builds....ok, I`m a bit off-topic now, but figured it might help with your workflow.

Hope this helps

[Tataku Yugen]

8 hours ago, Kyrah Abattoir said:

I know but i find it strange that @Tataku Yugen feel that he would have to rebuild each lod from scratch and UV them, so maybe I assumed wrong? But i still don't understand why he thought he would have to do that.

Please enlighten me.

 

If there's a wrong workflow I'll find it. Case in point: my day-job programming 🤣

 

 

[Tataku Yugen]

59 minutes ago, MaxMare said:

Before switching to substance, you need 2 models, a regular low/med poly with unbeveled edges (I almost never use bevel for SL) and another model with bevel edges, it can also have more defined geometry, btw bevel aka chamfer, insert loops etc will not mess up your UVs, edges/loops are added/placed automatically to existing maps, the only issue can arise if you later on move mentioned edges in which case UVs should be manually adjusted (I`m a max user so this is how autodesk software works)...ok so substance; save the complex model with _high suffix and the simpler one with _low suffix...once you open substance, import the simple one..The complex  aka high poly model should be added when  you open "bake mesh maps" tab (Bake/Normal/High definition meshes). With your scene set like this, textures are going to be created based on high poly model and applied to low poly model (with beveled edges and generally smoother). That said, you don`t always need 2 models, it is really up to you to decide when it is beneficial and worth the trouble and when not.

Anyways, now you have a decent medium or low poly model with maps that give illusion of more complex geometry...

If you want to create lower LODs, just remove any edges that are not necessary to keep your model base in shape so to speak... The important thing is to keep material count/faces number same and intact or else you won`t be able to upload to SL. So if a certain face is removed you can simply keep one triangle with that particular face number/material and it should work...The lower the LOD the less detail you need, just imagine you are viewing that model from a far and what would be visible, that will help you decide what parts are essential and what can be completely removed for lower LOD models...

When it comes to game asset creation it is generally advised to keep geometry as simple as possible. Tools such as smoothing groups, smooth/hard edges as well as normal baking are of great importance and definitely worth implementing...last but not least, good texturing can transform rather simple meshes in to complex looking builds....ok, I`m a bit off-topic now, but figured it might help with your workflow.

Hope this helps

That helps a lot. First I had no idea you could open two models in Painter. I'm still wrapping (no pun intended) my head around the idea of applying textures of one model to another, but I'm starting to internalize the concept that the UV is just a flat plane (duh). 

[Kyrah Abattoir]

Unless i'm mistaken the sole purpose of loading a highpoly in substance is so you can get substance to bake the different maps most of its filters need to paint in a geometry-aware fashion.