Short Division
I’ve been doing a lot of 3d tracking using the Pixel Farm’s PFHoe - it’s fantastic for the price ($99, or $199 for Pro), but it’s a limited version of its more $840 cousin, and you do start to notice those limitations. So here’s a few tips that might help my fellow low budget match movers.
- Check out the manual – I’m not used to software having manuals (seems to be a video thing) – turns out you really need to read this one. It’s hard to find some features without it.
- Know about the keyboard shortcuts – if you don’t read the manual, however, know that the spacebar brings up a secret menu in most steps, holding option while dragging zooms the viewport, and holding shift while dragging pans it.
- You do need to mask out moving objects – while it doesn’t have a built in way to make masks (I’ve been using Motion 5 – $50), not adding them really messes up the track.
- Keep some sort of cube in the shot – since PFHoe doesn’t allow you to set the focal length, you’ll need to estimate it using a cube (it also helps with estimating the ground plane). If you’re doing tracking on a green screen, you’ll want to put a box on it somewhere, or a box with a box on top if the floor isn’t in the shot. I ended up taping several together and covering it in tracking markers.
- If you’re tracking with a green screen – you’ll need to put tracking markers on it, and you’ll need to have something in the shot to demonstrate parallax, like a mic stand. There’s a really great 25 minute tutorial on placing tracking markers on the samples page for this course (it’s the second one down).
- If you’re shooting with a DSLR – don’t keep your apature wide open if you have tracking markers setup, you want them all to be in focus at once. You’ll also want to have you shutter speed higher than normal, probably at least 100 to reduce motion blur (also mentioned in this video).
- Check your start frames – if you’re noticing slippage in your 3d software you didn’t notice in PFHoe, make sure that the footage in your 3d program (if you have a video background on your camera for example) has the same start frame as the tracking data you imported. This is especially a problem in Blender.
- If you use Blender – know that it doesn’t work in the latest version, 2.5. It does, however, work in Blender 2.49, which means you import it into that version, save project, and then open it in the new version. It’s a pain. I’ve started developing a script that would let you import directly from 2.5, but haven’t been able to get some of the left-right handed conversion to work (so take a look if you’re good with python and math).
Also speaking of Blender, libmv is currently being integrated thanks to Google Summer of Code. So we’ll have open source match moving right inside Blender (you can check it out on the tomato branch). Seems to work pretty well so far, should be interesting to see how it compares to PFHoe.
My wife with our tracking marker setup.
Feel free to comment with your own tips!
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