[Bf-compositor] Image sampling issue

[Jeroen Bakker]

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 
> <mailto://lukas.toenne@gmail.com>) wrote:
>
>> Sebastian: Could you create a few test files to demonstrate the 
>> sampling issues?

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