We all know how useful Theia3D is for many kinds of biomechanics studies and human movement applications. However, there is even more you can do with it! This blog post is brought to you in collaboration with our dear friends at the Offenburg University of Applied Sciences, also known as Hochschule Offenburg.
This journey starts in a small town located in the southwest corner of Germany, called Offenburg. You wouldn't guess it, but here lies one of the most impressive biomechanical engineering laboratories in Germany, called the “Institute for Advanced Biomechanics and Motion Studies”. It has been established in large part thanks to the enormous efforts made by Professor Dr. Steffen Willwacher and his colleagues. In just two years, the university, Hochschule Offenburg, went from very minimal equipment to a brand new campus including state-of-the-art machinery and partnerships with some of the most influential sports groups in the world.
Hochschule Offenburg’s biomechanical department benefits from this development substantially, but there are other majors offered such as in business, IT, engineering, and media that can also make use of the available technology. While the media faculty at Offenburg is rather small compared to other universities, it's certainly not unknown. Dedicated professors and good relationships with local companies have helped in establishing a solid reputation within the student population.
But there was one challenge: the absence of a usable workflow for motion capture animation!
These circumstances combined to pose a very interesting question: is it possible to use the new systems at our campus to enrich the animation department with quality motion capture and help biomechanical students with the visualization of data?
The short answer is yes! In this article you will learn how to use Theia3D to translate scientific motion capture into high quality animations.
The first step after the measurement is recorded and processed in Theia3D is to go to “Settings” and check the “Use Animation Model” box:
Afterwards, you can reprocess the skeleton under “Analyze” - “Solve Skeleton” as shown below. Following this step, your recording is ready for export.
To export the skeleton, go to “File” and “Save Skeleton Poses…”:
Then, choose the FBX file type for your project. If you are unsure which export setting works best, save multiple FBX files with the various options. In this case, we are going to use Autodesk’s Maya software for animating, so we are going to use the compatible MayaZUp setting for the FBX file:
Once in Maya, load in the model you want to animate. This mesh will mirror the recorded movement. If your mesh doesn't have a rig, use the “Quick Rig Tool” under the Human IK Interface (a rig is the internal skeleton onto which the motion capture data will be translated). In this case we are using the standard animation model which can be found in Maya directly under the name “Human IK Example”:
If you have a mesh with a rig, go ahead and import the FBX file. Theia3D exports data with an attached model of a skeleton in order to make visualization of movement instantly possible:
In this case, the model is very useful to give the data a definition. Maya doesn't quite know what to do with this file, so in order to use it for our animation, we have to give it a character definition under the Human IK Interface. Click on: “Create Character Definition”:
Now we need to tell Maya which point on the model is which. Let's start with the feet. With a click on the left foot on the Human IK interface and a click on the left foot of the Theia skeleton, we define the left and right foot because mirror matching is activated by default:
Now let’s do this with every joint. Once the red X turns into a green checkmark, the character definition is sufficient to be translated to the animation model we loaded in first:
The last step is to set the Character to the animation model and choose the Theia capture as the source. In this case, “Dummy_Char” is the basic model provided by Maya and “Character1” is the exported Theia measurement:
Now the animation model is mirroring the captured movement. If you want to take this a step further, you can use custom models, real environments or make the skeleton disappear.
In summary, this is our basic guide to performing motion capture-based animations easily using Theia3D’s exported and rigged 3D models. This has been an excellent resource for our campus at Hochschule Offenburg as it allows us to use technology specific for our biomechanics labs as a tool for other programs. In the future, we will continue to use these visualization tools to help athletes understand their movement and technique better.