Mocha pro camera solve help(SOLVED)

Andersen01498 Posts: 1,005 Enthusiast
edited April 2019 in Post-production techniques

I am trying to camera solve this and im not getting a good solve please help!!!


  • Triem23
    Triem23 Posts: 20,079 Ambassador
    edited March 2019

     Hmmmmm... Tricky. Very low bitrate file, so lots of compression artifacts, and not good planes to track.

    I'll give it a try, but this isn't an easy one. Might have to render as an image sequence first.

    Edit 1. Thought I'd get lucky with a single track. This basically is a tripod shot. No such luck. Unfortunately the only viable second plane is the sky, and, on a nearly cloudless day, there's no texture to grab.

    Edit 2. You might be out of luck here. Certainly for mocha. There are several problems with this footage from a tracking standpoint.

    • Mocha is a Planar tracker. To solve a camera Mocha needs two static, relatively flat objects to track at all times. As the truck lands on it's side and starts to skid, before the camera pulls out, there are NOT two trackable planes. I can grab the road for the entire shot. There's a street sign to the right side of the frame, but it goes out of frame and mocha loses it. There's a street sign the truck hits. I can track that up until the frame it's hit. Unfortunately those two signs don't overlap as trackable. Once the camera zooms out you can try and grab the farmhouse in the background on the left of frame. Unfortunately that still leaves the section in the middle with no trackable data. The sky has no clouds/texture that can be tracked.
    • Also, there's a lot of wind at that location. If you step through the footage frame-by-frame you'll see that the streetlights on the right of the frame at the beginning of the shot are moving in the wind. So are the two street signs I mentioned. Again, Mocha requires static, non-moving objects to track for a camera solve. Those just don't exist in this shot, period.
    • Quality. To calculate the bitrate of a file we multiply the horizontal resolution by the vertical resolution then multiply by 24 (bits - this is 8 bits of reg, 8-bits of green, 8-bits of blue as encoded into the mp4). This give us bits per frame. Multiply this by 29.97 to get bits-per-second. Divide by 1024 for kbits/second. Divide again by 1024 for mbits per second. The uncompressed data rate of 1280x720 footage is about 630 megabits per second. This video is encoded at about 1 megabit per second. The compression ration is over 600:1. If you frame by frame through the footage at high magnification you'll see the edges of objects are shimmering quite badly. You'll see the texture in the road is changing significantly. All of these compression artifacts are removing the accurate details needed for a good track.
    • Besides Mocha I've also tried Ae's camera solver and Autodesk Matchmover 2014. Neither of those can get a good track, either. I suspect because of the quality issue listed above. This footage is compressed to the point where it's about to fall apart.

    Where did you get the footage from? If you can get a copy of the footage that isn't, you know, terrible, maybe there will be enough accurate texture data to track this. As I said in an earlier edit, this SHOULD technically be a single track for pan/tilt/zoom. Unfortunately the camera op kicked or hit the tripod at some point which moves the camera (and ruins the PTZ track). Also, again, resolution issues. Also, also, again, the street lights and street signs are moving in the breeze, so this shot just does not have two static, no coplanar objects to track anywhere in the shot. Even if you get a higher quality copy, chance are mocha still can't track it, unless better quality stops the texture shimmer enough for mocha to realize that road is static and try to calculate a PTZ track.

  • Andersen01498
    Andersen01498 Posts: 1,005 Enthusiast

    @Triem23 thanks I ran into the same issues, I found a workaround by tracking a lamp then adding another bezier anchor mask to the original bezier mask.   The main thing it doesn't matter what the actual tracking mask bezier is doing it matters what the surface tool is doing and the grid.  I was able to get a 99% track.  The things that i will be doing is implementing a tornado into the scene.  Thanks again for your suggestions.