• Adobe After Effects

  Tracking and the Film Back connundrum

  Posted by Eugen Olsen on September 20, 2008 at 6:08 pm

  I’ve thrown this out onto the most active forum in the hopes that someone will respond quickly… There doesn’t seem to be a matchmoving post, or I’m too tired to have found it. Forgive me.
  I’m currently working on some unconventional greenscreen footage and am getting some reasonable matchmove results in boujou and realviz matchmover, but I’m faced with a couple headscratchers.
  Firstly, the it was shot (apparently) on 35mm 2-perf with an anamorphic lens (which wasn’t noted) at 25fps. The lab unsqueezed the footage, and I’m stuck with 1990 X 865 footage (of all things) at a pixel aspect of 1. There is considerable lens distortion on the shots as well…

  So, my question is, now that I don’t have the lens information, my camera settings are a little up in the air. What I’ve come up with is a film back of 0.98″ by .426598″ – my lens distortion sits between .4 and .6 (on various shots).

  I’m getting very unpredictable results despite solid 2D tracking, so I’m assuming the problems are in the camera solve (i’m getting typical 3D solve issues). I’ve gone manual on most of the tracking, I do have some rough set measurements, but in general, problem solutions.

  I’d appreciate any words of wisdom from your infinite depths of experience, knowledge, and so forth…

  Eugen Olsen replied 17 years, 11 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Chris Wright

  September 21, 2008 at 6:47 am

  ” If the image is adjujsted in telecine, it is important to know where the principal point (the projection of the camera optical center on the film back) lies in the image.”

  Film a grid with each prime lens before u shoot.

  You can images warp before tracking with Shake, Inferno etc. to work on distortion-free footage.
  Pixel Farm, which also produces a Shake, Digital Fusion and AE plugin, can deal with high and low order radial distortions as well as distortions that change over a number of frames. Monet can calulate and export lens distortion data too.

  As for erratic keyframes, you could try switching interpolation to Auto Bezier, which will change the keyframes to maintain a smooth transition between keyframes.

  https://www.fxguide.com/article212.html
• 

  Eugen Olsen

  September 26, 2008 at 9:07 am

  Thanks man… worked out some undistort paramaters under monet and i’ve got some great results. Anamorphic lenses are hell for tracking though.

Reply to this Discussion! Login or Sign Up