The UMPM Benchmark: Data Description

Description of data

Per recording

We have split the data in a zip file for every recording. Splitting it has the advantage that you can choose to download a subset. Also, it limits the files to a manageable size. We supply some help to download all data easily by supplying a listing of all filenames. The files can be obtained from the download page

For every recording, the main zip file contains:

One configuration file

A json file that describes where all the other files can be found. As an example we take the following file (p4_ball_2.json):

{
  "id":"p4_ball_2",
  "bg":"backgr_l06_1",
  "calib":"calib_l06",
  "video_dir":"Video",
  "gt_dir":"Groundtruth",
  "bg_dir":"Background",
  "calib_dir":"Calib"
}
        

Four video files

Each file contains the video data from a synchronised Basler camera. The data is in uncompressed avi format, which is compressed afterwards with xzip. The filenames are ${video_dir}/${id}_${cam}.avi.xz, where video_dir and id are parameters from the config file and cam is one of f (front), r (right), l (left) and s (side). So, for instance Video/p4_ball_2_f.avi.xz.

Motion capture data

The ground truth data, containing all the labelled marker positions in C3D format. The filenames are ${gt_dir}/${id}${tp}.c3d, where tp is empty, _vm (virtual markers) or _ik (inverse kinematics). For instance, Groundtruth/p4_ball_2.c3d and Groundtruth/p4_ball_2_vm.c3d The virtual markers are explained on a separate page.

General data

Some of the data are not tied to a specific recording. Those are distributed separately. All zip files should be unzipped in the same directory, otherwise the correspondences described below won't hold.

Background data

For every video we supply a movie with just the background. The corresponding background can be found as ${bg_dir}/${bg}_$cam}.avi.xz. So, in our running example, we would have Background/backgr_l06_1_f.avi.xz.

Video calibration

The intrinsic and extrinsic parameters are recorded in a zip file. There is a Readme file in there explaining the parameters and an image that sketches the camera positions. The parameters for a particular recording are in file ${calib_dir}/${calib}_${cam}.ini. In our example that would be Calib/calib_l06_s.ini.

Description of C3D file format

The motion capture data is stored in the C3D file format. This format is used by several systems and organisations for recording motion data. The website http://www.c3d.org/ lists a lot of information about this format. Among others, there is the specification.

While we processed the C3D data that were produced by the Vicon Nexus software, we encountered a few points where the specification was not quite clear. See the page on the C3D file format for more details. On this same page we also explain how we recorded data for every label point.