The Xbox Kinect has long been seen as a possible tool for 3D artists and animators like myself. It has, for so long, been contemplated as a tool for both motion capture (Mocap), and for Photogrammetric scanning (3D reconstruction of complex environments). I took the liberty of testing a variety of Kinect techniques. What works? What doesn’t?
We will start with the bad: the Kinect suffers outdoors. Plagued by UV and IR interference, the Kinect cannot see past a few feet outdoors on a sunny day. We tested the Kinect while having it running pointed out the back of a moving vehicle, planning on using the Kinect as a tool to reconstruct a neighborhood in 3D, but due to the bumpy and dark asphalt surface in front of it, infrared light was easily absorbed, and the Kinect could not even reconstruct the road for this test. Its range was reduced to only a few feet. When stationary, the Kinect’s range extended to around 15 feet when pointed at a free standing object. We also tested the Kinect as a tool for scanning the facades of houses. I used a program called Brekel PointCloud to capture a pointcloud sequence of the house as I moved around it. The software captured a sequence of 3D mesh files, which were converted into an .obj sequence and manually reconstructed in Blender. This gave us mixed, partial results:
Brekel Pointcloud does provide a unique opportunity, however. Using the program, one can create 3D sequences, exported either as Alembic (.abc) or .obj sequences. Lets’s suppose, as a VFX artist, you wanted actors to interact with a 3D flood of water, created in post-production with a fluid simulation. With a Kinect, this should, in theory, be easier, as the actors could be captured in 3D by the Kinect, allowing the animated 3D mesh to be used as an obstacle object in the fluid simulation. In our tests, the alembic files created by Brekel did not work as collision objects in Blender’s fluid simulation, but I will update as we think of new ideas in the area.
Moving on to another Kinect program known as Kinect Fusion, the prospects of the Kinect as a stationary photogrammetry device become slightly better. In the video below, observe our efforts in the area. The Kinect is capable of producing a high-poly, low quality 3D mesh of the environment:
This brings a similar idea to mind. If animations of 3D objects captured with the Kinect cannot be used in fluid simulations, perhaps static ones can. This idea checks out, although we have not completed a full test. In theory, one could use the mesh output from Kinect Fusion as a collision object in a fluid simulation, and save a lot of time modelling the room. In fact, in the fast-paced, often rushed schedule of a 3D artist, this could save time and money. I will study this application further.
Outside of the realm of photogrammetry, the Kinect works well as a medium-quality motion capture device. Using Brekel ProBody, I was able to produce convincing .bvh files, imported into Blender:
I will elaborate on Motion Capture with the Kinect in a future blog post.
New Flight Digital Blog 