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I tracked a sequence of images and want to add a box to the tracked scene. All works well, and in the 3D view, if I change the current frame, the box looks aligned to the movie, which I use as a background.

When compositing, I have a RenderLayer node and the movie node combined using "over alpha". This works, but in the viewer, the rendered cube is at a fixed location (doesn't move with the scene), as it it's pinned to a single frame. The 3D view still works, and as I slide the current time, the cube moves with the movie.

Any suggestions?

Attaching a screenshot where the cube is aligned (next to the mouse) in the 3D view (bottom right), but not in the composite viewer (bottom left).

enter image description here

To make things more clear, here's a comparison of the 3D view (on the right) and the composite result view (on the left). First, on frame 20:

Frame 20

Now on frame 50:

enter image description here

And finally on frame 220:

enter image description here

In the composite output view, the cube is stationary while in the 3D view it's "moving" with the tracked camera.

Here's the blend file: comp_room2.blend

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  • $\begingroup$ Could you upload your .blend or add more screenshots? As it is now, there are many possible things it could be, so we can't do much more than speculate. $\endgroup$ – gandalf3 Oct 17 '13 at 2:27
  • $\begingroup$ Added a few more screenshots and a link to the Blender file. $\endgroup$ – Barak Oct 17 '13 at 5:32
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    $\begingroup$ You have to re render every frame $\endgroup$ – Greg Zaal Oct 17 '13 at 7:04
  • $\begingroup$ So I must be missing something. Isn't the composer responsible for that? Do I need to re-render just my Layer? How do I actually do that? $\endgroup$ – Barak Oct 17 '13 at 8:17
  • $\begingroup$ Greg, your suggestion, of course, works (I was hoping I wouldn't have to do that manual work). Can you put it as an answer so I can mark it as accepted? $\endgroup$ – Barak Oct 17 '13 at 8:22
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You have to rerender each frame in order to update the comp. You can do this by pressing F12 to render the whole scene or clicking the render icon on the layer node to render just that layer.

Render a layer

It would be simple to add the possibility of rerendering when the frame is changed, but in reality most renders take several minutes (sometimes hours, or days) to render and thus accidentally changing the frame would clear the render and you would have to wait for it to finish again.

Of course this option could be disabled by default, but I don't see any serious use coming from this and thus it's not worth the effort to code.

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  • $\begingroup$ Note: I have a very basic task, with a single render layer, which I rendered completely (all 252 frames). Still, when I went to composite, it didn't "use" that info. I can use F12 to update things. Thanks. $\endgroup$ – Barak Oct 18 '13 at 17:05
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    $\begingroup$ @user1145012 You could load the rendered image sequence/video back into the compositor with an Image or Movie clip node and use that instead of the Render layer node. That way blender will do compositing on the already rendered frames. $\endgroup$ – gandalf3 Oct 19 '13 at 19:18

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