Motion Capture Week 6/7 - Cleaning Up Data in Cortex

Both this week and last, I got to use the Cortex Software to clean up our Motion Capture Recording Data. It was actually quite a fun process and satisfying when it worked well. My group and I split up our 25 usable MoCap shots equally so we could all do some clean up. I got given 5 shots:

- civilian_panic_run_1_variant_1

- civilian_walk_1

- duck_behind_the_counter_1

- head_turn_1

- peek_behind_counter_2

Cleaning up the MoCap data is neccessary because within the data there are gaps in the recording where the 24 cameras have been unable to detect or track individual markers on Jasmine's body. Using Cortex, we can go through the data and patch up the gaps to identify the location of the missing markers manually.

The clean up process was fairly straightforward. First we load the MoCap Data into Cortex, then we find the areas which need cleaning up by pressing the N key, then we assess the situation and figure out which tool is necessary to patch up the gaps correctly.

The three tools we used in Cortex were Marker I.D., Cubic Join and Virtual Join.

- Marker I.D. is used when there is an unidentified marker in the scene which the computer doesn't recognise. Sometimes there can be two unnamed markers, in which case one needs to be assigned and the other needs to be removed.

- Cubic Join is used when there is a small number of frames that have no visible markers. It tells the computer to take the last known position of the marker and the position it appears at again and create a direct path between the two.

- Virtual Join is used when there is a larger number of frames that have no visible markers. When using virtual join, we need to select the three closest markers to the intended marker and the computer will use their relative location to the intended marker to determine its own location during the frames where it's been undetected.

Note: Cubic Join can only be used for small number of frames because the computer is dumb and will calculate the fastest, most direct route between the marker positions. It tries to be as efficient as possible. In reality, this is not always accurate. For larger gaps, it is better to use Virtual Join.

Here are some screenshots of the Virtual Join process. Because of the large number of frames in the gap, I chose to use Virtual Join instead of Cubic Join.

1. Find a Gap

2. Scrub through and check for an Unnamed Marker

3. Select the entire gap

4. Click on Virtual Join

5. Virtual Join Window pops up

6. Select the 3 Closest Markers to the Intended Marker and put them in the Origin,Long Axis and Plane Marker slots

7. Click Join Virtual

8. Watch Back over the footage to look for abnormality (glitches, to change one of the virtual join reference markers)

If everything looks fine, it's cleaned and done!

Cleaning all of my data took about 2 hours altogether, and I didn't come across any issues thankfully. The files were exported out as .TRC files for use in Motion Builder.