Investigations on Genesis 3 joints in Daz Studio Chapter 1-8 (including PDF documentation)
Singular3D
Posts: 499
Characters in Daz Studio are based on a hierarchy of joints. These joints can have one or no parent (in case of the root joint) and zero to multiple children. These joint chains or hierarchies are bound to a mesh with a weight map and thus drive the body mesh by rotation, translation or scaling of the joint. Thus, joints are a major tool to pose a character and deform the body mesh in the correct way. Additionally, it may be supported by joint controlled body mesh morphs, which enhance the deformation based on the quaternion weighting in Genesis 3.
To transfer a Genesis 3 character from Daz Studio to another program and to be able to pose this character there in a similar way like in Daz Studio, you need to be able to transfer the joint skeleton, the weighting and the joint controlled morphs, which should work in the same way, as in Daz Studio.
While investigating these things, I had to understand how Genesis 3 works in Daz Studio and compiled this in a document, which I would like share with this nice community. Hopefully this is valuable for some of you. If you have questions, let me know.
Daz 3D is part of 
Connect
DAZ Productions, Inc.
224 S 200 W, Suite #250
Salt Lake City, UT 84101
Licensing Agreement | Terms of Service | Privacy Policy | EULA
© 2024 Daz Productions Inc. All Rights Reserved.
Comments
Dropping a quick note to say that I've DLed your document and skimmed through it quickly. It's obvious how much work you've put into this, and I just wanted to say thank you - it's much appreciated. I'll certainly be going through it in more detail when I've got the time.
- Greg
Same here. Thanks.
Glad you like it. I'll post the Chapter 6 as well, when it is finished.
Chapter 6 may take a while though...
The skinning is actually dual quaternion, but maybe you can achieve the same effect with quaternion rotations, not sure. You also have to apply scaling separately beforehand.
In any case, some good info in there. I liked the part about the spline. I wasn't aware of that.
In case anyone's interested, here's a link to a thread I made a while back about the difference between linear matrix blending and dual quaternion blending for joint deformations:
http://www.daz3d.com/forums/discussion/134926/adding-dual-quaternion-support-to-unrealengine4-images-inside
The reason for showing this is that morphs will not look right if you don't use the proper skinning algorithm.
Note that the dual quarternion skinning looks even better now as I did not have antipodal corrections back when I created that thread.
Thanks. The dual quaternion skinning is exactly the same as the spherical skinning in Cinema 4D. So when I get Genesis 3 via FBX to Cinema 4D, she is deformed in the same way. Unfortunately the JCMs are not automatically transferred and that was the start for my investigations. I can attach them manually, but I'd like to do it automatically. So I try to write a script to export this additional information.
Thanks for the link and info.
I'm doing something similar with UE4 to load JCM's. I'm very interested in your section about the bones.
Started to go into more details. UE4 uses a left handed ZYX system. DAZ Studio uses a right handed XYZ system. The letters mentioned are Right,Up,Forward. So I could swap the X and Z coordinates, but the Bend, Twist and Side-to-side angles have me nervous. It looks like the Y angle can stay the same because the X and Z coordinates are swapped and the left-right handedness difference will cancel that out. I think that swapping the X and Z angles should do the trick. The angle directions will be swapped which is what I want because of the handedness difference.
1. Swap X/Z coordinates.
2. Swap X/Z rotations.
Gonna start by seeing if I can load a static mesh. Then I'll try adding bones and weights. Should be interesting.
BTW: Anyone know how Catmark subdivision is different from Catmull-Clark? I'm familiar with Catmull-Clark and actually implemented it once. But what's Catmark? Is it even related?
I have a asimilar issue with Cinema 4D. Y and X-Axis are the same, but the Z-Axis goes backward in Cinema 4D. It works, when I do an FBX import and use negative values for rotations around and translations along the Z-axis. Try FBX, as you get the weighting, bones and UV maps.
Your work is simply great.
About morphs location (in Ch. 5.1): morphs in /Morphs directory may not be directly linked from figure's .duf/.dsf as this directory is recursively scanned for morphs by Studio (the same is true for UV maps, clones etc.). Also, morphs may be embedded into any DSON file, this is useful when you want self-contained figure that is easy to copy.
Catmark is Pixar's augmented/enhanced Catm[ull-Cl]ark. I didn't see any paper with detailed description of what was changed so OpenSubdiv source code is the best reference.
Edit: For DS figures Catmark has to be equal to Catmull-Clark because they do not use per-edge sharpness feature.
What is the purpose of your UE4 work?
Thanks for the information. At the moment I'm primarily interested in the JCMs (and MCMs), as they can be exported via FBX as alternate shape, but the connection (ERCLink) is lost. I have to rebuild these in Cinema 4D as well as the joints, that control other joints (e.g. foot and heel). If I create a new character in Daz, the morphs will be baked into the mesh, if they are not dependent on joints. My final goal is to be able to pose the character in Cinema 4D like in Daz Studio. The clothes will be dynamically as well as the hair.
So I try to get the information out of Daz via Script...
Maybe it's better to add support for .dsf/.duf to Cinema as first class objects, i.e. directly load .duf without intermediate FBX?
I myself found more convenient to directly process DSON files for my purposes (clean or mirror weight maps, bake shaping morphs, switch texture sets) without touching DS scripting or plugin SDK.
I added a 6th chapter to the PDF
I added Chapter 7 to the PDF
Thanks, just getting to chapter 6!
Thanks. I looked at pixar's library. Even recommended it at work. We may not use it, but there may be some interesting ideas there. In UE4, I'm trying to create a game. I just want proper JCM's. I have dual quaternion with scaling support added. I also added support for TIFF import. But I have no idea how to even begin adding a new geometry importer in UE4. I might try looking at the Alembic importer again, but it's quite massive. I'm just trying to see if there's an interface to implement or what.
Importers are currently tightly coupled into UnrealEd and there is no such thing as say plugin interface for new importers to implement. Epic once said that such thing may happen in the future but it will be some distant future I think :)
Also I've found that using JCMs in UE4 is coming with too much performance penalty (if you're planning to have more than a dozen characters on screen). So I'm currently making new base figures based on Genesis3 that:
I've made a prototype, brought it into UE4, learned a lot and now deep in making Mk.2 which will be a production version I hope :)
Thanks! That's good to know. It will save me from fumbling around the code for nothing. I want JCM's mostly for the main character and possibly bosses. I already have dual quartenion skinning and I'm not seeing any performance issues there. So I can reuse the same bends and JCM's as G3F. I may dispense with trying to change the rotation order. I'm still not sure it matters with dual quaternions.
Wow, I just noticed your PDF.
Incredible !!!!
Especially for someone like me who is new to Studio and trying to figure out the basics. Thanks much !!!
At the moment I'm working on Chapter 8 and I got 61 pages so far. In order to finish the chapter, I have to investigate some more things.
If you are interested in a pre-version let me know.
thank you
Outstanding work. Thank you !
Valuable? No, not in the least; I consider it invaluable! Particulary a text-based tutorial, which is much too rare nowadays, thanks a LOT you magnificent bastaird!
This pdf is great. You are very generous for making this available. Thank you.
Here is Chapter 8. Unfortunately it is not finished so far, but I wanted to share it anyway.
Here is also a little script as well, which will work from version 4.8 on.
You've attached a script of yours (dsa):
This script exports Genesis 3 joint values, dependencies between joints and to morphs // 2015-05-27 copyright Singular3D
instead of a chapter 8 PDF document
The PDF with the chapter 8 is at the beginning of the thread :)
oh, thanks. Sorry
...hmmmm...your 1st post has no PDF attached to it whatsoever anymore
I can still see the PDF.