Camera extracting problem

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Old 03 March 2013   #1
Camera extracting problem

Hi!

I followed Aurety's video tutorial I bought at video2brain (Matte Painting, in french).

I'm stuck now trying to extract the camera matched material, by converting the "Camera Mapping" into a "UVW Mapping", choosing "Generate UVW Coordinates" (right click on the camera-mapped material). The material gets badly shifted.

What am I doing wrong?
Attached Images
File Type: png CameraExtraction.png (90.6 KB, 47 views)
File Type: jpg CamaraMapping_UVW_problem.jpg (58.3 KB, 64 views)
 
Old 03 March 2013   #2
Hi
Try to subdivide your geometry more before you generate UV coordinates.

Cheers
Bonsak
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Old 03 March 2013   #3
hey ! Thanks for watching my tutorial ! Hope you like it..

Yes Bonsak say well about the geometry subdivision.
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Old 03 March 2013   #4
Bonjour Aurety
Yes I like the videos very much (I've been happy to pay for).

Still, subdividing the objects doesn't help… I see the improvement but it's not as good as expected. Their remain little wavy distortions.

And, for large scale architecture scenes I can't subdivide the model while still modeling.
Could I bake the material instead?
 
Old 03 March 2013   #5
Does it look different if you toggle Enhanced opengl? I see your problem with not wanting to subdiv your geo very much.

Cheers
Bonsak
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Old 03 March 2013   #6
It doesn't seem to be enhanced GL...
I will have to find another way to get a satisfying result. I'll stick to camera mapping as long as possible.

Anyway: why is this shifting happening??
 
Old 03 March 2013   #7
Hm. I had this exact problem a while back but i cant remember how i solved it

Cheers
Bonsak
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Old 03 March 2013   #8
Keep me posted!
 
Old 03 March 2013   #9
Alright, I had some feedback from Simon Wicker, expert matte painter

So basically, this is to be expected, since the UVW information is low quality with so few polygons (hence why the accuracy increases when you subdivide the mesh).

There shouldn't be any reason for you to convert to UVW mode anyway, since camera mapping has been designed specifically to avoid these sorts of problems, is pixel perfect and much more flexible (if you need to update your geometry, you won't lose your projection, contrary to UV mapping).

Why did you need to convert to UVW in the first place? You don't really need to extract the matched material, since it will look exactly the same as your original reference (the UVs are adapted to fit the material, not the opposite).
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Old 03 March 2013   #10
Thanks a lot for your time fluffouille

I wanted to duplicate and move an object (part of the image) to another place as long as the parallax shifting is not too obvious. Of course I can move the projecting camera along with the object.

Just out of curiosity: would the same distortion happen if I'd bake the material?
 
Old 03 March 2013   #11
Do you also have the problem while rendering or only in the viewport?

Sometimes it appears to be distorted in the viewport but renders fine.
 
Old 03 March 2013   #12
Originally Posted by EricM: Do you also have the problem while rendering or only in the viewport?

Sometimes it appears to be distorted in the viewport but renders fine.

Good catch. Seems to only appear distortedd in the viewport. Renders fine.
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Old 03 March 2013   #13
Hi
Did you render the 2nd test scene I attached above? And compare to the camera mapping.
My rendering is less wavy but still crunched...
Attached Images
File Type: gif UV_distortion_render.gif (36.2 KB, 14 views)
 
Old 03 March 2013   #14
you can think of uv mapping to be like trying to pin down a piece of cloth on a windy day. very simple geometry only provides a few pins to lock your texture down so other parts are free to 'flap' around. by sub-dividing your geometry you provide extra pins that help to hold things in the correct position.

if you really have to convert this to uv's then you might get better results by using bodypaints projection painting to project the image onto a cleanly unwrapped uv set (use optimal mapping to create undistorted uv polygons).

cheers, simon w.
 
Old 03 March 2013   #15
Simon
Thank you for the explanation.
I will dig deeper about BP and unfolding facades without distortion.

So far: subdivision we need!

But why is there no function within the camera calibrator R14 to "bake" the projection _without_ distortion... Maybe just a flat projection without camera... Maxon?

In his tutorial exercice (house in the forest), Auretys extracts a balustrade with a 20x20 subdivided plane, stating that this is an error using this much polygons, but in fact it's the way to go it seems. So that's what had me confused initially.
 
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