[postgis-users] Rasters (once more)

Frank Warmerdam warmerdam at pobox.com
Sat Oct 15 09:17:20 PDT 2005

On 10/15/05, Patrick <pvanlaake at users.sourceforge.net> wrote:
> * How to integrate palettes? Externally using a reference field or
> internally in the raster band record as a binary field?


I would expect palettes to be optionally associated with bands.
There are many models for palettes, have you thought about
how you want to model them?

Simple: 256 entries, an RGB color for each entry.

 o Transparentency: add an alpha for each entry.
 o Variable Size: allow any number of entries.
 o Ranges: allow a color to be applied to ranges of values.
 o Non-integer values: Input values are doubles.
 o Color models other than RGB.
 o Specify a start and end color over range.

> * How to integrate attributes for ordinal data types?

Wouldn't the attributes just be another (non-spatial) table?

> * Should tiles have a fixed size globally, be fixed system-wide, for a the
> raster, or establish it at the level of the band? How does the answer to
> this question bear on implementing OGC GC evaluate* methods?

Is there a particular reason not to allow setting the tile size on
a per-band basis?  In many cases, for small images, it will be
desirable to treat an entire band as one tile.

Rather than (or in addition to) the Pascal code, can you post
the schemas for supporting tables and examples of how an
image would be stored expressed as SQL table definitions?

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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