LUMIERA.clone/doc/devel/rfc/NormalizedDeviceCoordinates.txt
Ichthyostega b556d2b770 clean-up: comb through the historical pages to fix markup errors
Some sections of the Lumiera website document meeting minutes,
discussion protocols and design proposals from the early days
of the project; these pages were initially authored in the
»Moin Moin Wiki« operated by Cehteh on pipapo.org at that time;
this wiki backed the first publications of the »Cinelerra-3«
initiative, which turned into the Lumiera project eventually.

Some years later, those pages were transliterated into Asciidoc
semi-automatically, resulting in a lot of broken markup and links.
This is a long standing maintenance problem problem plaguing the
Lumiera website, since those breakages cause a lot of warnings
and flood the logs of any linkchecker run.
2025-09-21 05:40:15 +02:00

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2.8 KiB
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[options="autowidth"]
|====================================
|*State* | _Parked_
|*Date* | _2009-01-14_
|*Proposed by* | ct
|====================================
Normalized Device Coordinates
-----------------------------
_AkhIL_ pointed out to me some blender problem and how ``renderman'' fixes that.
We should use this too.
Description
~~~~~~~~~~~
Just snippet from IRC log:
------------------------------------------------------------
[15:09] <AkhIL> and I hope lumiera will use some resolution independend
measuring for all parameters
[15:09] <cehteh> one can rotate where the node actually sits
[15:09] <AkhIL> like NDC
[15:09] <cehteh> or pass transistions through the renderpipe, make all effects
transisition aware and apply them at the end
[15:10] <cehteh> the later is better but needs more efforts and some rethinking
[15:10] <cehteh> we will prolly support both in lumiera :)
[15:11] <AkhIL> in renderman's NDC for horizontal image with 4:3 aspect ration
(-1.33,-1) is lower-left corner and (1.33,1) upper-right
[15:11] <cehteh> ah
[15:11] <AkhIL> so moving to different resolutions and different aspect ratios
in renderman makes no problems
[15:11] <cehteh> well good point, we will measure in pixel but need to convert
between them . using a float would be good to address pixels
[15:12] <cehteh> yes
[15:12] <cehteh> what stands NDC for?
[15:13] <AkhIL> Normalized Device Coordinates
[15:14] <cehteh> ok
[15:14] <AkhIL> so from -1 to 1 is a range by smallest image size
[15:15] <cehteh> yes sounds reasonable
[15:15] * cehteh adds a note to the lumiera design docs
[15:15] <cehteh> so far we dont do anything where it matters .. but that will
come
[15:16] <AkhIL> when you move some logo to (0.8,-0.8) it will stay on screen
even when you chenge resolution and image aspect ratio
[15:17] <AkhIL> all input images should be scaled to this range (-1,1) by
smalles side
------------------------------------------------------------
Rationale
~~~~~~~~~
^[red]#to be written#^
Comments
--------
One issue where I always assumed we'd need to define something of this sort is
for proxy editing. Especially this is a problem in conjunction with masks.
Basically, this means a bit more of ``vector graphics''. With film/video editing,
this was rather unusual, but with the advent of more and new digital video/film
formats it gets more and more important. Also, our considerations regarding
time handling and quantisation to single frames somewhat fit into this line of
thought. Up to now, rather the standard way of thinking was to use a ``project
framerate'' and a fixed resolution in pixels. But we certainly can do better.
Ichthyostega:: '2009-01-14 18:09:50'
Parked
~~~~~~
deferred for later, generally accepted.
Christian Thaeter:: 'Thu 14 Apr 2011 03:06:42 CEST'
''''
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