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(This is in blender cycles.) So I have a tank animation with a green backdrop and on that green backdrop I put a road so it looks like the tank is moving on the road. But the video clip of the tank is stationary so is there a way to move the video clip across the road backdrop to make it look like the tank is moving across the road? Also is there a way to reposition the tank like rotate it to make it aligned with the road backdrop or rescale it? I wish I could send a pic to make it easier but stack exchange crashes when I do.

(This is in the compositing node editor) So my node set up is the army tank with green backdrop in a movie clip node connected to the image of the keying node which is connected to the 2nd image slot of an alpha over node which is connected to composite. The road image is in an image node connected to the 1st image slot of the alpha over. enter image description here

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  • $\begingroup$ This may be just me but I don't completely understand - What do you mean stationary? Isn't the tank moving in your animation? $\endgroup$ – Unnamed Sentient Being Jul 7 '16 at 1:06
  • $\begingroup$ if you can't upload an image as part of your post, upload it somewhere else and add the link to your question. Without images is hard to understand what you want to do. $\endgroup$ – cegaton Jul 7 '16 at 1:15
  • $\begingroup$ If youi created the animation in blender there is no need to use a green backdrop, just use an empty background and enable film>Transparent $\endgroup$ – cegaton Jul 7 '16 at 1:16
  • $\begingroup$ I didn't create the animation in blender and by stationary I mean the tank wheels are moving and stuff but the tank isn't going anywhere. $\endgroup$ – Austin H. Jul 7 '16 at 1:19
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    $\begingroup$ @AustinH. Not an answer to your question, but to make screen grabs on blender, press Ctrl F3 and save the image. You can choose to save the whole screen or just the active window. $\endgroup$ – cegaton Jul 7 '16 at 5:40
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How I would do it

Your best bet for scaling, rotating, moving, and animating all that stuff would be through the VSE.
1. In the compsitor remove the green background to make adding the background easier later on using the keying node.
2. Open blenders VSE and add in your newly rendered transparent video through SHIFT+A > movie
3.With your clip selected add a transform strip via SHIFT+A > Effect Strips.. > transform. Once there you can change the size rotation and location all from the properties panel on the timeline. Your probably going to want to keyframe the movement of the tank so using the timeline put the timeline where wish and using the transformation strip you can change how the tank looks relative to the frame. Hover over the location, roation, and whatnot and then press "i" to keyframe it.
4. After you render that run through the compsitor with an alpha over node and add your pic - that should do it.

References

https://www.youtube.com/watch?v=h0F5X4b7jug http://blenderartists.org/forum/showthread.php?261401-how-i-add-or-active-keyframe-for-VSE-blender https://www.youtube.com/watch?v=0PZ_cxjxexM

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  • $\begingroup$ Thanks but one issue I can't figure out now is that since the background image and video were shot with different cameras there are different dimensions, so blender tries to stretch the background image to align it with the tank and it makes the edges of the image look very blurry and glitchy looking. $\endgroup$ – Austin H. Jul 7 '16 at 16:42
  • $\begingroup$ using the scale node in compositing doesn't work? $\endgroup$ – Unnamed Sentient Being Jul 9 '16 at 16:12
  • $\begingroup$ I haven't tried the scale node, I will see if that works. $\endgroup$ – Austin H. Jul 9 '16 at 17:04
  • $\begingroup$ The scale worked successfully thanks, I have one last question. How would you change the time position of both the backdrop of a video and the main video scene? The video and backdrop both play at the same time when I want to have the backdrop play at a different time than the start of it. $\endgroup$ – Austin H. Jul 9 '16 at 19:38
  • $\begingroup$ Another problem I encountered is that the video looks perfectly fine but when I render it, it shows white pixels around the objects and it looks all fuzzy and messed up. $\endgroup$ – Austin H. Jul 9 '16 at 19:46

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