Track to and up axis problem

I have a camera moving along a tube. It has two constraints: a Follow Path, and a Track To, in order to point to an Empty that is following the same path with an offset of frames (this Empty is also used as the DOF object).

The problem is that in order to keep the camera pointing “up”, the Track To constraint sometimes makes the camera rotate 180° in a non-continuously way, making the animation very nasty in those frames. I attach two screenshots that show the problem (frame 19 and frame 22), and the constraint configuration of the camera.

Thanks in advance!


Can you get rid of the track to and lock rotation at the corners ? will that work? and if you want to make it look like its flying you can give it a little bank / rotate into the turn. you can keep the empty and add a copy rotation to the camera and use the empty object and lock rotation on the empty.

Kazinger, I dont understand you exactly. Do you mean using both constraints, using Track To in the straight sections and Lock Rotation in the curves?

Using Lock Rotation to the empty in the entire path does not work because the empty has the same problem, it rotates very sharply in some sections.

thanks for your response!

Have you tried unchecking the ‘follow path’ option? Shouldn’t need it if you are using a track-to constraint, I think…

My thoughts are if the curve is twisted, that’s why the camera is twisting. You can also clear the tilt of the curve (the twist) with alt-t and set the tilt with ctrl-t.


Edit: maybe post a .blend so I can see the curve better?

Randy, thanks for responding, the follow Path was checked by mistake, but unchecking it didn’t solve the problem (i think Track To was overriding the Follow Path option). The curve has no twisting, and every point has radius 1.0.
I m animating the rotation of the camera manually right now. :S it would have been very nice to make it work with constraints, so I could change the tube and everything would get adjusted automatically.

I don’t know if this is part of the problem, was why I suggested disabling ‘follow path’ option…
It was supposed to be fixed in 2.5.

Maybe I don’t understand the question but its a easy thing to make the camera follow a object down the tube and look at the same object . Is that what your looking to do? You can use a curve for curve deform and the same curve as a path If that what you need. and change the path and tube with the same curve. Its also easy to keep the camera rotation. . Depends on the effect you want…look like its chasing…Or more mechanical … or roller coaster . Sorry I think i still don’t understand .

Yes Kazinger, maybe I didnt explain me correctly, but thats exactly what I want to do. Im using the path used as the tube’s curve to make the camera fly through it, it works fine except some frames where the camera rotate very sharply, maybe its the bug mentioned by Randy. In the screenshots I attached, you can see how the camera rotates 180 degrees in only 2 frames (see the little UP arrow of the camera’s object).

Except for those frames and a few other, it works perfectly.