Corrective shape keys

A common problem in rigging is that mesh deformation is ugly close to joints, especially in the shoulder, groin, elbow and knee areas. A popular solution is to use shape keys to correct the deformation. This idea was implemented in the MHX rig a long time ago, cf. http://sites.google.com/site/makehumandocs/blender-export-and-mhx/blender-export-and-mhx-249/body-shape-keys. However, I have been quite unhappy about the corrective shape keys for a long time, and recently came around to give them a complete overhaul.

To get good deformation is extra tricky for the MHX rig, because it needs to work not only for a single character, but for all characters that can be generated by MakeHuman. Eventually it should be possible to "bake" corrective shapes from pose engine data, but for the time being there is just one set of shapes, defined for the default character. To adapt the shapes to other characters, I now simply scale them with the size of the relevant limb. Here are some examples of bone deformation for different characters, without (red) and with (blue) corrective shape keys. We see that there are still some artefacts, especially for the toddler, but in my opinion deformation is better with than without the correction.







Blender has other means the deform a mesh. J P Bouza, of Blenrig fame, recommends using mesh deform rather than pure bone deformation. It does not seem practical to implement this for the MHX rig, since it requires a custom cage for each character. But if you are doing your own rigging, mesh deform is definitely something to look into.

Presently the corrective shape keys only work for the FK rig, due to a bug, or misfeature, in Blender 2.5. Namely, the rotational value of a bone is not updated when the bone moves due to constraints, so it can not drive the shape key. Thus, if we move an IK hand, the upper and lower arms move in the viewport, but their rotations are not updated and the corrective shape keys never kick in.

Anaglyph 3D mode in makeHuman.

MH modelling now can be even more cool, using the new 3D Anaglyph Mode.
To activate it (using latest svn). Just press the "3d glasses" icon showed in the image below.

The first click will activate the "Toe-in" mode, the second mode the "Off Axis" mode. These are tho common projections used in 3d view. The second should be more comfortable, but you have just try them to see which one is better for you. A third click will deactivate the 3D Anaglyph Mode.

Well, have fun!

MakeHuman, Blender and the Mocap tool

My first video tutorial.

Poll: Where to save files

Something about Hairs

Here are some announcements regarding hairs (only for nightly build users):

We did a little improvement with hair interpolation algorithm (mostly improvements you can see with the aqsis renderer within makehuman).  

I created two new hairstyles (afro and peaky hair). Both amateurish but acceptable. So they are now in the library. Afro shows a thumbnail and is much improved than before. Long hair aqsis renders has been fine-tuned. I will then fine-tune the other hairs (peaky, curly and short) for a better aqsis render.

Another great announcements is regarding donations of new hairstyles by other users (see my tutorial in a previous post). We have several amazing new hairs (all male hairs) and after I have fine-tuned them for adapting in makehuman you will be seeing them in the Libraries. So stay tuned for that. To the users (among them some really professional artists) who donated these new hairs, thank you very very much and keep it coming. And for those who haven't donated and who plan to create some new hairstyle, maybe you could consider donating us some of your hairstyles :)

If I get a little time I will then post a tutorial on two things:

1. How to fine-tune blender-created hair for makehuman (esp. for the aqsis renderer)
2. How to make better curly hair strands with blender particles (e.g. the one similar with afro but maybe a bit better).

The year is not yet over, so to our users, fans and testers: Please stay tuned!

First test of mocap tool

The last few weeks I have been working on a tool to transfer mocap data to the mhx rig. Here is the first test.



This is obviously far from perfect. The back bends back and the feet skid when she is turning, because the bone angles in the loaded bvh rig are not quite the same as in the mhx rig. Even more seriously, the character does not move on the floor, which was compensated by tilting the camera. Motion retargeting is still very primitive, and will be improved in the future. Doing motion retargeting is in general a very difficult problem, but less so between similar characters. Therefore the mhx rig has been redesigned to look similar to the mocap files from www.accad.osu.edu/research/mocap/mocap_data.htm. It is probably not possible to use the tool with bvh files from elsewhere.

The mocap tool can be found in svn in the same directory as the mhx importer (importers/mhx/blender25x), and works with some recent Blenders. But Blender's API is still changing rapidly, so it might soon be broken again.