[Bf-compositor] Image sampling issue

[Sebastian König]

Hi all!

I have created a new wiki page: http://wiki.blender.org/index.php/Dev:Ref/Proposals/Compositor
I will collect the proposals and requests there, and also try to merge it with requests and proposals from here:
http://wiki.blender.org/index.php/Dev:Ref/Requests/Compositing2.6

I will also start threads in this list mailing list, as Francesco suggested, so that we can discuss things more clearly and structured. 
What I would like to see at some point is some kind of priority list. Everyone has his main issues and problems with the compositor and also probably a pretty clear vision what should be changed and how. Would be cool if we can get agreement on the most important issues.

Cheers!

Seb



On 3. November 2013 at 09:21:30, Jeroen Bakker (j.bakker at atmind.nl) wrote:

Hi!

Just to clarify the issue, the quick solution and an draft-idea of the possible solution:

Issue: the compositor can not handle sub-sampling with good quality by default. Nodes that want to use it should currently implement a style like UV mapping (EWA sampling). To use EWA sampling the pixel size needs to be evaluated (DX, DY).

Quick solution: let the plane tracker node calculate the pixel-size and EWA filtering methods. This solution will work for most cases, but is not the ideal solution. It would be better that the pixel size is known by all nodes.

Possible solution (draft idea): In stead of evaluating pixels with just an X, Y coordinate or even X, Y, DX, DY. We should investigate on using 3x3 matrices. This solution should also help to implement canvas compositor, but it could lead to strange results as matrices are limited by the optimization structure (Complex vs Simple nodes) of the compositor.

Jeroen

On 11/02/2013 04:48 PM, Sebastian König wrote:
Hi!
Here’s a file that illustrates the problem with sampling of plane track: http://www.pasteall.org/blend/24971
It’s a UV grid that is being blurred quite badly, even though the plane track has only straight lines.
I was talking to Jeroen and Sergey about that, and they said there are issues with the entire sampling code in compositor, so it seems not to be a local issue. 
But I don’t know about the technical issues. It just looks crappy. :)

Cheers!

Seb




--
Sebastian König
Schenkendorfstrasse 45
04275 Leipzig
Germany
+49 176 20319318
www.3dzentrale.com
koenig.sebastian at gmx.net


On 2. November 2013 at 13:20:56, Lukas Tönne (lukas.toenne at gmail.com) wrote:

Sebastian: Could you create a few test files to demonstrate the sampling issues?

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