I’ve done some searching and can’t seem to find a way to fix this issue…
I have nice smooth dolly shot on curved track, and the camera is panning the opposite direction the camera is moving.
This shot seems to confuse blender. I get a nice smooth solve, but the camera is inverted. The solved camera dollies in the opposite direction, and it pans the opposite direction. Blender solves interpreting the 2D track points incorrectly…it thinks that the close points I’ve tracked are far, and the far ones close. The image I attached shows the solved camera path and direction, and also shows what the correct solved path should be like (white grease pencil).
The final solve shows the 3D tracked points lined up correctly over the footage, but because the camera is inverted, the 3D points backwards…the far ones are close and the close ones far, etc.
Is there a way to tell blender what 2D points are far, and which are close? Has anyone else run into this issue? I’ve tried re-tracking it from scratch, but I always get the same result. I could go try this shot in syntheyes or mocha pro…but I like blender…=)
That’s pretty odd. The only thing I can think of, is, try using the tripod setting. I know things are calculated a bit differently using this setting. in the toolshelf under ‘solve’, check the box that says ‘tripod motion’.
One thing to try is just rotating the solved camera 180 degrees in the x axis.
Did you use the tools to orient the scene? I’ve come across situations like yours where the tracking is correct but the camera is upside down ( z axis inverted). Try setting some trackers as floor and some as wall in the solve-> orientation tab.
I don’t think tripod solve applies here, since the camera seems to be moving sideways in an arc as is panning in the opposite direction (its hard to tell, though)
I tried to invert the solved camera but I had a few weird issues with that. Also the problem is Not that my coordinate system is not set, e.g. the camera is not just upside down. The actual solve is 'mathematically correct" but the depth is inverted, which makes all the camera moves backwards. Think of it this way. Normally with a dolly move, the objects in the distance move slowly, whereas the objects that are near the camera move faster. Because my shot is panning in the opposite direction than the dolly is moving the camera, that phenomenon is inverted…e.g. the wall the in background is moving fast whereas the chair in the foreground appears to be moving slowly. Blender’s solving algorithm must be weighted to assume that 2D tracks that are moving slower must be deeper in the shot.
I tracked this same shot in Syntheyes, a professional match-move software, and it had the exact same issue. It inverted the depth, and everything was moving backwards. However, syntheyes had an option to tell the software which direction the camera was supposed to be moving. I told it that the camera was moving to the right, and it solved the shot perfectly, fixing the issue.
I don’t think blender has a feature like this, but some things are hidden…
If you can reshoot the room with more parallax, that would be preferable. Even if you don’t want a lot of translation in the final shot, just edit out that part with a lot of movement.
Another thing you can do is use helper frames shot from different points in the room to help with parallax. Sebastian Konig has a tutorial how to do that…
(skip ahead to about 6:20 to see the part about helper frames.)
It is actually a very interesting mathematical problem. Perhaps you should get Sergey or Keir to take a look at it, because this demands the use of constraints during the solve.
Probably inverted perspective. This could be a product of not enough tracking markers and not enough parallax between markers. I was one of the very first users of SynthEyes and its predecessor Scene Genie. Inverted perspective is a common problem in 3D tracks.
Just looked at your footage. Are you tracking enough points in the foreground and the background? Is there anywhere I could download the footage to take a look at my own results?
By any chance did you double click on any of the y or x axis when doing the scene coordinate orientation… If so, this could be the issue. I had this same problem before. When you select your two markers for the y/x axis and double click, it asigns a rotation of 180 degrees on the z-axis. This is not a bug, just a hidden or unknown function/feature. Boujou has this feature when working with its coordinate system. It has a button that say rotate 180 degrees around the origins axis point.
