Saturday, April 28, 2012

How to Make Animated Peeps #3 ~ MoCap & BVhacker

Screen capture of the BVhacker program

This is the third in a series of tutorials that guide you through the process of sourcing and using applications that enable you to create 3D animated characters visible in most (but not all) modern web browsers. The ambition is to show you how you can create a demo of a character with a suitable motion in a matter of minutes.

MoCap

One of the many methods for animating 3D computer models is to use motion capture (MoCap) data .
http://en.wikipedia.org/wiki/Motion_capture

The are many formats available for storing MoCap data:
http://en.wikipedia.org/wiki/List_of_motion_and_gesture_file_formats

BVH & CGspeed

A popular file format for MoCap data - and the one used in this tutorial - is the BVH format:
http://en.wikipedia.org/wiki/Biovision_Hierarchy

There are a number of sources for royalty free BVH files. Thomas Larsson (introduced in tutorial #2)  lists a number of sources on pages 70-71 of his book:
http://makehuman.blogspot.com/2010/11/making-short-movie-with-makehuman-and.html

A huge resource he mentions is the repository of over 2600 MoCap files produced by Carnegie Mellon University:
http://mocap.cs.cmu.edu

The files have been updated by Bruce Hahne and the updates are available on his web site:
http://www.cgspeed.com/

The particular versions we need are the BVH files updated the be compatible with Autodesk Motion Builder and are available at CGspeed's data warehouse on Google Sits:
https://sites.google.com/a/cgspeed.com/cgspeed/motion-capture/cmu-bvh-conversion

BVhacker

You may well have to look at many dozens of MoCap files in order to find the ones that please you. In order to speed up and simplify this work you can use BVhacker:
bvhacker - home

If you have any questions about BVhacker, there is a Google Group for the app that seems quite responsive:
https://groups.google.com/forum/?fromgroups#!forum/bvhacker

You can drag and drop BVH files onto the BVhacker display window and the animations will start playing very quickly. BVhacker provides numerous tools for editing and enhancing BVH files. I ended up using none of the capabilities because I preferred making the minor edits I needed in Blender.

Do note, however, that my interest in this tutorial is in making fast and 'cheap' animations but not necessarily quality animations.

Future versions of MakeHuman will also allow you to view BVH files and it is also possible to do so in Blender, but for the time being BVhacker is the fastest and easiest tool for the job.

What You Need To Do: Download a BVH file

Clink on the link to CGspeed's data warehouse provided above.

Scroll down until you see"2010 RE-RELEASE DOWNLOAD LINKS AND CAVEATS"

Download one of the BVH repositories. They are dozens of megabytes but each contains numerous BVH files. I suggest the first is a good place to start and it's only 32 megabytes.

Once its downloaded and unzipped, use BVhacker to select one of the BVH files that you would like to use in your first demo. For this tutorial, I used file '08_07.bvh' which shows kind of a strutting walk.

Coming Up

In the next tutorial, I will cover importing the MakeHuman 3D model data into Blender and applying the BVH MoCap to the model.


Next: How to Make Animated Peeps #4 ~ Blender: