Rasters, TileIndex and Shapefiles - Oh My! Really Confused

[Ed McNierney]

Chris -

 

Let me suggest you try to get unconfused just one step at a time!

 

"it uses one .gif (the big map pic), attaches the big map to the globe
via a world file.  That big map .gif had no georeferencing info attached
to it."

 

That's a bit of a contradiction.  A world file is one way of providing
georeferencing.  If you've got an image "attached" to the Earth via a
world file, you've georeferenced it.

 

MapServer makes maps, not pictures.  One of the chief differences is
that a map has geographic location information associated with it.  When
you ask MapServer to generate a map for you, you need to tell it the
location of the map you want in some coordinate system.  In order for
MapServer to know which of your GIF images to use in making the output
map, it needs to know the geographic location of each of those images.
Otherwise it couldn't figure out which ones to use.

 

A TILEINDEX is step two in the process.  Once you have a set of more
than 1 properly georeferenced images that you'd like to use like a
single logical image, you can create a TILEINDEX to do that.  But you
have to completely and correctly make it through step one first.  Once
you get the individual images properly georeferenced, gdaltindex will
just work.

 

So - what do you know about these images?  Do you really have a world
file that correctly describes your big GIF image?  Do you know exactly
how the little images were created from the big image?  If so, you
should be able to figure out how to generate world files for each
individual image.  If not, you'll need to get that information for your
big image.

 

If you do have that world file and know how the tiles were created, let
us know (you can post the world file in your reply - it's just six lines
of text).

 

-          Ed

 

Ed McNierney

TopoZone.com

 

 

________________________________

From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Christopher Harris
Sent: Wednesday, September 26, 2007 10:02 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: [UMN_MAPSERVER-USERS] Rasters, TileIndex and Shapefiles - Oh
My! Really Confused

 

Hi.  I have a map that is broken up into a bunch of .gif tiles.  I want
to display them on a layer in Mapserver.  I have working version of what
I want to accomplish, but it uses one .gif (the big map pic), attaches
the big map to the globe via a world file.  That big map .gif had no
georeferencing info attached to it.

These .gifs have no georeferencing information included or attached as
well.

I read Section 4 (and Section 9 too) on the mapserver site page:
http://mapserver.gis.umn.edu/docs/howto/raster_data