[postgis-users] Raster suggestions?

[Jeshua Lacock]

On Mar 8, 2008, at 8:07 AM, Nicolas Ribot wrote:

> How do you plan to serve your data ? A map engine (perhaps MapServer)
> and a web application ?

Hello Nicolas,

Yes, correct, initially a web server to web browser. I also might want  
to someday make a standalone application that could be distributed on  
CD or DVD. I also have the need to create maps in-house. Currently I  
tile individual quadrangles that I have created together manually - I  
need a more automated solution. My most immediate need is to create an  
in-house solution, then an online solution, followed by a DVD/CD  
solution.

I am not entirely sure if I will be using MapServer or a home-brewed  
solution. I am leaning towards at least seeing if MapServer will work  
for me before I develop something myself.

> Do you actually need to store rasters into the database ?
> If you only need to display them or serve them through webservices,
> you could georefence them in postgis, storing their spatial extension
> and file name, but not the actual image data (and some other
> information you might find useful, like image dimension, date, image
> category, resolution, etc) into a 'raster' table, then use your map
> engine configuration to integrate this information into your
> application.
>
> We often do the following when serving rasters in a web application:
>
> 1. Create a raster table to hold filename, image's bbox, image's  
> date, etc.
> 2. Populate this table with a python script using gdal/ogr to generate
> images' information (bbox, size, date, description, etc)
> 3. Eventually create views on this table to create logical groups of  
> rasters
> 4. In MapServer, define one or several layers referencing these views
> and use these layers as tileindex in RASTER layers. MapServer will
> then use postgis views the same way it uses shapefile tileindex.
>
> You can then query all your geo data (vector and raster) using postgis
> functions.
> You can also easily create new views/mapserver layers on the raster  
> table.
> You don't have to deal with TB of storage inside PostGIS.

Thanks for the information!

Sounds great.

I wonder how small I should mosaic the raster imagery. Does the size  
of the mosaic tiles determine how coarsely the image can be panned?

For instance, if I tiled the imagery in 1000 meter blocks, would the  
client be able to pan say 10 or 100 meters, or would they have to be  
panned in 1000 meter increments?

> PS. I can provide you with a simple python script that scans some
> directories to find images and generates SQL queries to insert into a
> raster table defined as follow:
> CREATE TABLE rasters

I would like to take a look at it if you don't mind emailing me...


Thanks again,

Jeshua Lacock
Founder/Programmer
3DTOPO Incorporated
<http://3DTOPO.com>
Phone: 877.240.1364