[postgis-devel] WKTRaster Scale and Skew

[Mateusz Loskot]

On 10/09/10 17:16, Pierre Racine wrote:
>> Width is computed based on scale & skew?
> 
> In 99% of the cases there is no rotation and pixel width & height ARE
> synonyms for scale X and scale Y.

Pierre,

Have you researched this aspect and collected statistics?
I hope we've agreed to stop betting which use case is more
frequent and which not :-)

> Is it worth changing their names?

I don't tink so.

> How does GDAL name it?

There is know official terminology here, but in documentation
GDAL usually uses pixel width and height.

>> We separate the accessors for the pixel width and the georeference
>> component that is now used as the width.
> 
> You mean creating a "truepixelwidth" function? Same reluctance since
> it is not really a width when the pixel shape is a diamond.

I agree.

> But you could say "this happen only 0.001 of the time"...


Yet another interesting statistic?

> Does that mean removing or renaming the ST_PixelSizeX and ST_PixelSizeY function?

I personally think there is nothing wrong or confusing in those names.

SizeX is a synonim to width and SizeY of height, also in GDAL.

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net
Charter Member of OSGeo, http://osgeo.org