[Mapserver-users] Recommendations for multiple query of invisible layers.

[Ed McNierney]

Jason -

OK - it sounds like step 1 is to figure out the actual geographic extent
of each image, since you can't do a "what images overlap this spot?"
query of ANY sort without that knowledge.  The shapefile route's pretty
simple, and it's also easy to migrate that data into a relational
database when you need to.\

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242  

-----Original Message-----
From: Jason M. Nielsen [mailto:jnielsen at aero-graphics.com] 
Sent: Monday, February 09, 2004 3:56 PM
To: Ed McNierney
Cc: mapserver-users at lists.gis.umn.edu
Subject: RE: [Mapserver-users] Recommendations for multiple query of
invisible layers.

Quoting Ed McNierney <ed at topozone.com>:

> Jason -
> 
> I'm not sure I understand - are these georeferenced images?  I don't 
> care whether they're orthorectified, but if you don't have the 
> geographic extent of each image I don't see how you're going to do 
> what you originally wanted to do.
> 
> 	- Ed

The aerial photos only have a center WGS84 point. This was created while
the plane was in flight using GPS.

So in the most basics of georeferencing yes they are but I do not have
actual TIFF World files for them nor are they GeoTIFFs. That is, the
upper left coordinate and pixel sizes etc do not exist but I do have a
known coordinate point on the photo and I know its angle of rotation
from true north.

As far as I know I need these world files or the images need to be
GeoTIFFs in order to 1)Even put the photos into place and hence
reference the query area back to them. 2)Use tileindex to create a shape
file indexing the tiff files.

In order to make the world files I would have to generate the upper left
coordinate based off of the center coordinate I have, the pixel size
generated from the scale of the photography and the angle of rotation
from true north (kappa?).

I think for now I am simply going to use a shape file. Ill work towards
having this data stored in a db later.

Thanks.

-------------------------------------------------
This mail sent through IMP: http://horde.org/imp/