Hello,
 
I've got a scene using a hand-held camera which results in notable camera shaking (typically as each step lands on the ground) and therefore considerable motion blur.  You can see a Divx6 version of scene here:
 
http://www.stevewarner.com/Downloa [...] -divx6.avi
 
The auto-tracker failed to produce a solid track so I've tracked the shot by hand.  This has given good results, but not perfect results.  You can see a test render from MatchMover Pro here:
 
http://www.stevewarner.com/Download/TableMatch.avi
 
Notice that the box looks quite solid, however the pyramid in the background appears to jump around a bit.  I'm not sure why that's happening and would be thankful for any advice on how to resolve it.  But my main question revolves around motion blur.
 
What's the best way to handle motion blur?  Should I manually place keyframes where I think are best in the blurred fames, or should I just leave those out of the tracking altogether?  Currently I'm manually placing 'Intermediate' keys everywhere there's motion blur.  I generally find the center of the blur area and am selecting that as the position for my point.  But is that bad?  Motion blur is the result of the camera moving too quickly.  If I select a mid-way point on each frame with blur, will I be causing the 3D solver to miscalculate the camera motion for that frame?  If so, where should I place the 2D track point?  Or is it just better to set an 'Intermediate' key at the last in-focus frame, then skip over the blurred frames, then pick it up again after the motion blur with another 'Intermediate' keyframe?
 
Thank you for any help and advice you can provide with this.
 
Cheers,
 
Steve

Hi,
 
Motion blur is definitely a problem. Anyway you should always try to provide a position for all tracks, instead of having holes. The best way is to place them visually if possible. Else MatchMover provides several tools in case it's too tedious: you can place the tracks before and after the blur, and interpolate it (using the 2D interpolation), or track them bidirecionnally.
 
In your case, remember also to always put 2D tracks where you're gonna insert CG objects, to be sure that the camera will be accurate there.
 
Here's a preview:
ftp://ftp.realviz.com/private/support/render.avi

Hi Ronald,
 
Thanks for the helpful tips!  I had success over the weekend by adding more manual tracks so that at least 6 good tracks were available at every frame.  That really helped.  It also helped to set my reference frames manually, although I was surprised to find that reducing the key placement for the 3D solver to every 10 frames wound up in a less accurate match than setting the keyframes to 30.  Would you mind sharing that MatchMover Pro project file?  I'd be interested in seeing your setup.
 
When I went back and retracked the project on Saturday, I ended up placing tracks in just about all the same places you did (barring a few).  However I noticed that while the floor was very solid, when I tried to position objects on the table in my 3D application, they moved around quite a bit, even though the markers on the table seemed to stay in place in MatchMover Pro.  You mentioned making sure I placed tracks in all the places I wanted to integrate 3D objects.  Would you say the problem I'm describing is from a lack of tracks in that area?
 
Thanks in advance for the help,
 
Steve

Hi man, just to throw my 2 cents in regarding motion blur.
When tracking heavily blurred scenes it doesn't matter too much which part of the motion blur you track just as long as you remain constant throughout the whole sequnce. Either track the leading edge, the trailing edge or the middle of the blur and stick to that with all tracks all the time and you should be fine.

Awesome.  Thanks for the clarification on that!    
 
Cheers,
 
Steve

that's ok for a good 3d solve but to get a matching motionblur in your 3d renderings you should always track the middle of the blurred marker. (as this is the actual position of the marker at the current frame)
 
basti

"you should always track the middle of the blurred marker. (as this is the actual position of the marker at the current frame)"
Huh? How does that work?
If you look at my bad drawing, if you throw a ball from point A to point C and take a picture at point B you will see a blur maybe like my diagram 1. At this moment in time the ball will be at the front of the blur as in diagram 2, the ball won't be in the middle of the blur as in diamgram 3.
You can't photograph an object occupying a space before it has got there! That would be time travel.

hi
 
a lot of people get that wrong. in the captured frame the ball has been exactly* as long at the beginning of the blur as it has been at the end. so the center of the blur ist the correct position for your tracker as it is the midpoint of the way the ball has gone in this captured moment.
 
(*kind of depends on shutter speed but normally it's correct)
 
watch reallife footage of eg. moving balls. what you are trying to describe would be motiontrails which are common in motiongraphics but do not apply to real life footage.
 
basti

hmm, yeah I see what you mean.
So during that exposed frame the ball (asuming its going at a constant velocity) would have been in all the blurred position for the same length of time so using the middle just averages it out?

exactly! and you can take a constant speed for granted almost all the time because it's pretty sure that an object does not accelerate between 1/25 second (except ufo's maybe)
 
basti

So do you always put tracks mid blur? Personaly I use the leading edge as I find it easier to keep the track more acuratley in place.

yes always, because this is the only way to get the motioblur of your renderings matched exactly to the plate. of course it's a bit more timeconsuming to find the exact center but it works
 
basti

Nice, cheers. Didn't really consider how the motion blur on the cg down the pipeline is affected by my track placement.
I'll have to try that.