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I am searching for an in-image effect in the compositor.

I have two identical scenes (only the cameras are different). One for the background, 800x600 pixels. Second scene has the camera with a closeup on a detail, 320x240 pixels in rendersize.

One pixel of image one should cover one pixel of image two.

Can I put the second image on top of the first, partially covering the background, without rendering the detail image separately? I'd like a solution best which does not require or produce any scaling since I use wireframe.

enter image description here

Like that, only with higher resolution.

If I use the scale node, it destroys the wireframe (and for some weird reason distorts the cube as well):

enter image description here

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  • $\begingroup$ The scale node changes the smaller image which is exactly what I don't want to do. I want the 320x240 Image to remain 320 x 240. $\endgroup$ – Haunt_House Jul 13 '16 at 13:45
  • $\begingroup$ Well, yeah, it's about compositing two scenes, but it's two scenes of different render size. That's the problem. Unless 2.77 can do something 2.76 can't, I hven't found a solution yet. the 'in one go' part of the question is what I'd like to know. $\endgroup$ – Haunt_House Jul 13 '16 at 13:55
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In order to have 2 scenes at different resolutions while rendered together without any saving render results to file you will need to setup 2 scenes (in this case for saving resources it would be useful to create linked copy of the scene; make sure to make camera single-user so it to be scene independent). Use Render Layers nodes with scenes selected and make transparent or crop image of the scene at the lower resolution; after that overlay scenes as usual.

The Crop node will allow to make all the pixels of the image at lower resolution become transparent so that the background image will be visible as expected, without any stretching:

Crop Image Size
When enabled, the image size is cropped to the specified region. When disabled, the image remains the same size, and uncropped areas become transparent pixels.

Crop node in manual

Once scene at lower resolution is made transparent in empty areas, most likely you would like to translate it by X or Y axes with Translate node to see the background image as desired.

screenshot of node setup and final result

This can also work with Crop Image Size enabled with the only difference that image of the scene at lower resolution will be cropped and not made transparent in empty areas.

Note that if one of the scenes was changed, it's possible to rerender only it and see the final overlayed result once compositing nodes process it.

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  • $\begingroup$ Pretty much the perfect answer. I was much too focused on rendering with different resolutions. $\endgroup$ – Haunt_House Jul 19 '16 at 13:48

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