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I am following this tutorial:

https://youtu.be/gKZ1tOf2daI?t=527

  1. How to translate the foreground video (blond girl) to the left of the background image ? I used a Translate Node, but coupling this node with a Scale node (to modify the size of the foreground movie) leads to bad results, essentially, the mask only select a little part of the foreground image (only the nose for instance). Maybe I should respect some order between scale node and translate node but I didn't find a good solution.
  2. In the video editing tab, I created a movie in the movie sequence editor. I would like to use this movie as a foreground image. What node should I use in the compositing tab to do so ? (this movie is just a sequence of images, but it is easy to choose the time where to change the image with the movie sequence editor).

Here is my node editor:

Node Editor

Here are the two images (among 6) that I want to use as a foreground: foreground1

foreground2

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  • $\begingroup$ Please provide some images to your setup as well as the link to the tutorial you are referring to. $\endgroup$ – Mike Pan Feb 15 '18 at 0:09
  • $\begingroup$ Answering Part 2: You cannot send the output of the VSE to the compositor, sorry. You would have to render it first or copy the values (from the VSE Strip) for frame start and length to a Image/movie node. $\endgroup$ – 3pointedit Feb 15 '18 at 4:24
  • $\begingroup$ Also you should use an Alpha Over node to combine a keyed image, instead of a Mix node. $\endgroup$ – 3pointedit Feb 15 '18 at 4:26
  • $\begingroup$ Part 1: The mask node is rendered at Project dimensions, if your image is not the same size then the mask will not fit. Even if you have drawn it to match in the MCE or UV Image editor. $\endgroup$ – 3pointedit Feb 15 '18 at 4:28
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Part 1: The Mask node is (usually) see below rendered at Project dimensions. If your image is not the same size as the Blender project then the mask will not fit. Even if you have drawn it to match in the MCE or UV Image editor.

In this image notice that the mask was drawn to fit around the cube but the rendered version is to small.

mask and render mismatched

Use Scale node with Render Size selected, and choose Fit if the aspect ratio of the image is different to the render dimensions.

Mismatched aspect

Notice that the Mask node can be in Scene Size...

Mask Scene size

*...or you could make it a predetermined size (to match your source media)

independent mask size

To move the keyed image around, first use the Set Alpha node then the Transform node. You can choose to filter these transformations with Bicubic (better quality).

transform node

Also you should use an Alpha Over node to combine a keyed image, instead of a Mix node.

Answering Part 2: You cannot send the output of the VSE to the compositor, sorry. You would have to render it first or copy the values (from the VSE Strip) for frame start and length to a Image/movie node. There is a script that will do this for you. Related Can I add the output of the VSE as input to the node diagram?

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