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

[Jason M. Nielsen]

I have a map currently consisting of mosaiced orthographic imagery covering
an entire region. This is setup and working.

I also have data indicating the centers of photos covering this area. In
addition I have attributes for each photo consisting of scale, flight angle,
etc.

These photos all overlap.

What I would like to do is be able to query an area inside of mapserver and
have it return information about each photo that intersects with the query
region.

First thought was to create a shape file representing the bounding box of each
photo and have all the desired attributes attached to this file. Then I could
simply query that layer (containing that shape file) and print the returned 
attributes.

The first issue I thought would occure with this is I do not want these bounding
boxes visible on the map being displayed in mapserver. Is it possible to perform
a query on a layer without having it visible?

The second idea was to put just the center points etc into a postgis db. At some
point the bounding boxes would be automatically calculated based off of the
center photo coordinate, scale, pixel size, x+y pixel size of imagery, etc.
These pre or post created bounding boxes would then be what are queried in order
to determine intersection. They in turn would have to be linked back to the
center points in order to get the "metadata" sought after.

>From my crude diagram below you can see that a query could result in either a
single photo being returned or quite possibly even if the query box falls only
within one photo it could return two or more as well. There could be any number
of photos in a line overlapping and they would be overlapping on all four sides
with other photos accept the photos on the very outter edges will normally not
have any overlapping imagery to their outside(direction from center of project).

001 : photo 1
002 : photo 2
--- : edge of photo
|   : edge of photo
+   : photo center point
=== : overlap area of two photos 

      001    002
-------========--------
|      |      |       |
|      |      |       |
|      +      +       |
|      |      |       |
|      |      |       |
-------========--------

Anyhow, the real question here is wether anyone has recommendations on the basic
method for doing this? ie: Are the lines Im thinking along a decent method by
which to accomplish this or am I on the wrong track or making it more difficult
than it really is etc.

Thanks, Jason.


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