Match bg image to output resolution/proportions

General discussion about Cycles 4D.
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rojharris
Posts: 16
Joined: Fri Nov 24, 2017 5:22 pm

Match bg image to output resolution/proportions

Post by rojharris » Thu Mar 08, 2018 10:03 am

Hi There,

I'm having a nightmare trying to get a super basic thing to work: I have an image I want to render objects into and normally in cinema I'd just load it into a bg object and 'frontal' map it, making sure the output dimensions of the scene match the image. Simple... However in cycles I cannot make it work.
I have loaded up the 'HDRI Split' scene from the sample page and in there I've put my HDRI for IBL and also my BG image. I then changed the mapping (using a texture coordinate node) of the bg image to camera... doesn't work, the bg in the render view is way too big. I tried all the different mapping options, like 'window', 'generated' etc but nothing shows the image properly in the correct proportions. I even tried a new scene with a simple environment material and just my image. still didn't work. Changing the mapping on the environment object doesn't work either.
I need to be able to render over a bg plate using a shadow map object and get my lighting from a different image and/or sun sky setup. How do I set this basic thing up in cycles?

I've read and re-read the manual and searched this forum but can't find anything that works. I think its just a mapping thing. I even added a plane with look-at-camera and tried to frontal map onto it but no luck....
I'm hoping this is a easy as it should be...

Thanks

rojharris
Posts: 16
Joined: Fri Nov 24, 2017 5:22 pm

Re: Match bg image to output resolution/proportions

Post by rojharris » Thu Mar 08, 2018 10:22 am

Update: I've almost got it to work by swapping the 'environment texture' node for an normal 'image texture' node in the HDRI split material. I say almost because the actual render is working (after setting mapping to window and flipping Y axis) however the IPR is scaling the image up to its full window size which makes it a pain to match lighting and seamlessly integrate objects...

Edit: Un-ticking 'fit' in the IPR makes it work properly.. phew!

Is this the best/only way to do this though?

Thanks

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Martin
Posts: 546
Joined: Sat Dec 17, 2016 12:03 pm

Re: Match bg image to output resolution/proportions

Post by Martin » Thu Mar 08, 2018 2:53 pm

Hi rojharris,
hard to tell and imagine what are you doing there without any examples or node setup screenshots.
The best way always is to upload simplified scene so users can have a look and answer quickly.

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