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 » » Steve Warner | The Tips and Tricks forum was empty so I figured I'd start a thread here where everyone could offer their own tips and tricks for getting the best results with MatchMover Pro.
Being a new user, some of my tips and tricks are going to be fairly obvious. And in many cases, they're simply repeats of other things found in the manual and this forum. But hopefully they'll help other new users to get up and running without having to read every thread to glean useful bits of information. (If I'm wrong on any of these tips, please don't hesitate to correct me.)
1. Avoid compressed video file.
MatchMover offers the ability to work directly with compressed video files, but even newer compression models such as Divx and Xvid can affect the video in ways that will hinder MatchMover's 2D tracker. It's best to use an uncompressed video file or a sequence of frames. A frame sequence can be created easily by importing the movie into a program like Virtual Dub (freely available from www.virtualdub.org) and choosing File/Save Image Sequence.
2. Always have at least 6 tracks visible at any time.
The 2D tracks are used to help solve the 3D camera info (motion, field of view, etc.). If you don't have enough tracks visible throughout your sequence, the results of the 3D matched camera will be low. Make sure to have as many good tracks available as you can before you attempt to solve the camera.
3. Get to know the Preferences for the 2D and 3D tracker.
The preferences for the 2D and 3D tracker aren't just preferences that you set and leave without thinking about them again. Rather, they should be set on a shot by shot basis. The MatchMover Pro manual describes these in detail, but here's a simple case in point. "Smart Prediction" is ideal for smooth camera moves. But if your camera is jumpy, make sure you turn Smart Prediction off before you start tracking your 2D points.
4. Changing the Keyframe Step setting in the 3D Tracking preferences can really affect how well the program calibrates the camera. The manual says that lowering this setting (which will produce more keyframes) will result in more accurate calibration but a longer processing time. I've found, however, that in some cases, lowering this setting actually resulted in worse calibration (along with much longer processing time). So be sure to adjust this. I'd recommend starting with a setting around 30 or 40 and working down from there until you're happy with the results.
5. Focus and Variation for 2D tracks.
It's important to vary the placement of your 2D tracked points. Doing so helps MatchMover Pro spot the parallax in the shot and produce a better camera match. But it's also important to place as many 2D points in the area that you want to integrate 3D objects. This is especially true for manual tracking as opposed to automated tracking.
6. Survey Info
If you're on the scene when it's filmed, it can be really helpful to take measurements. Even if you don't take measurements, if you know the location (or even part of the location) of certain points, you should enter that in the Survey Info under the 3D tab for the track properties. For example, if you know that a certain point lies on the ground (hence it's Y value = 0), but you don't know its X or Z value, simply activate the Survey Info and keep the Y value checked but turn off the X and Z. Doing so will help the program know that these points like directly on the ground and will aid in the camera solving process.
7. Choose when to manually track
The autotracker works great in many situations, but don't be afraid to also use manual tracked points. Tracking key points by hand first, then running the auto-tracker will help nail down MatchMover Pro when it goes to solve the 3D camera. You can also manually add tracks after running the auto tracker to futher solidify the results. In many cases, manual tracking can provide outstanding results with only a handful of tracks, and the fewer tracks will mean less calculation time when solving the 3D camera.
8. Tracking across motion blur
If you're tracking a shot that contains motion blur, you'll probably be forced to postion a number of keyframes for your 2D points by hand. When doing so, keep in mind that motion blur is caused by a fast move of the camera. Try to determine which way the camera is moving during the blur and then approximate a postion for your 2D point with that in mind. When solving for the camera motion, this will help reconstruct the sudden motion that caused the blur in the first place, allowing you to recreate it with motion blur in your 3D application.
9. If you're running a forward or backward track on a 2D point and the tracker unexpectedly fails, there are a few things you can check. First, check to see whether or not the area you're tracking has left the frame or is getting too close to the edge. If it has, designate the last good frame as a Stop frame and then pick it up again with a Start frame when the feature has at least 20 pixels showing on the screen. If it's not moving off screen and the tracker still stops, it may be that the feature has become too faint for the tracker to identify. Simply reposition the track point slightly to pick up on a bit more of the contrast in the area you're tracking. I've found that this will often help the tracker continue and usually doesn't affect the quality of the tracking.
10. Pay attention to field order
One of my first tracking efforts was with the sample lion statue footage that comes with the program. The auto tracking worked great on this shot and 3D objects placed in the scene in MatchMover produced rock-solid results. But I was having a lot of trouble reproducing those same results in my 3D program. The problem turned out to be one of field order. That slight 1/2 frame difference was enough to cause my objects to slip and slide rather than stay synced with the footage. So pay attention to your field order!
11. LightWave tips.
These tips are for those working specifically with LightWave. First and foremost, you should know that LightWave handles field order different than MatchMover Pro. If you're using Odd/Lower field order in MMP, you'll want to set the field order in LightWave to Even/Upper. Be sure to do this in the Image Editor and not just the Camera properties. The field order needs to be chosen in the Image Editor in order to work properly. Another point to note is that if you export a scene from MMP 4 that contains 3D objects, those objects will not appear in the correct position in LightWave. The simple solution to this is to rotate the object 180-degrees in its heading. Then it will match the position you placed it in in MMP. Lastly, if you use the object mapped with your background footage, your render times will drastically increase. If you want to speed up the render (especially for test purposes), set the footage as your background media in the Compositing tab of the Effects window. |
wesm | Hi Steve,
Thanks a lot for creating this thread! It's been a lot of help.
I am having some issues with slipping. I am new to MM and I am trying to export the Basic tutorial camera to lightwave. I export the scene and place a ball object into the scene. The ball is slipping. I changed the field order to even in the image editor, but it's still slipping. I saw a thread about a patch on the exporters. It's from oct 2006. I downloaded MM yesterday Mar 21 2007, so I'd think that it's not an issue of a patch.
Do you know what could be going on?
thanks,
wes |
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