[Mapserver-users] Geotiff and Extent confusion

[Ed McNierney]

Michael -

I think Dylan's two suggestions are correct.  I just wanted to add that
you need to be a bit careful using the data you have in a GIS system.
The TopoZone Pro downloads let you retrieve the original data we get
from the USGS, the Tennessee Valley Authority, and the State of
California.  The primary reason we provide that feature is so TopoZone
Pro subscribers can look at the map collar information (revision
history, township/range labels, etc.) that gets cut off in TopoZone.

We're finding that many people are using this as a source of GIS data.
That's OK, but the data's very messy and inconsistent - when we say we
let you download the data as we get it, we mean exactly that <g>.
You'll find that some of the data (from the TVA, for example) aren't
GeoTIFFs, some is projected in NAD83 and some in NAD27, most is UTM but
California is in an Albers projection, most are 250DPI but California is
400DPI and many newer DRGs are 500DPI, etc., etc.

The TIF/TFW files should work correctly for the simple example you're
trying, but if you try to expand beyond that one file you may hit quite
a few bumps in the road.  One of the major tasks in creating TopoZone in
1999 was to figure out how to normalize all this messy data!

Let us know if you have any trouble with the file after you've looked at
Dylan's suggestions.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com
ed at topozone.com


-----Original Message-----
From: Michael Hughes [mailto:mike at probass.com] 
Sent: Wednesday, December 24, 2003 2:57 PM
To: Mapserver-users at lists.gis.umn.edu
Subject: [Mapserver-users] Geotiff and Extent confusion

I hate posting this because I see the same question posted again and
again in the list.  Unfortunately there are no real answers on the list
or the wiki, so here it goes again.

I have installed mapserver 4.01 and verified that it works via the demo.
I have downloaded a USGS GeoTiff file from topozone and the associated
tfw file.  I adjusted my map file to attempt to load the tif file
instead of the pngs created for the demo.  Of course I cannot get the
darned thing to display.  I am sure that the problem lies in the extent
settings.  I am just not smart enought to fix it yet.  The values
provided by gdalinfo do not match the values provided in the tfw file
just to add to my confusion.  I am trying to simply display the image
with the mapping server, without adding overlays or anything else at
this point.  I am sure that it is simply a newbie mistake that is
keeping me from displaying the image successfully, hopefully someone can
help me out.  I have provided all of the information that I think is
applicable below.

Michael Hughes


./mapserv -v
MapServer version 4.0.1 OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP SUPPORTS=PROJ
SUPPORTS=FREETYPE SUPPORTS=WMS_SERVER SUPPORTS=WMS_CLIENT INPUT=TIFF
INPUT=EPPL7 INPUT=JPEG INPUT=GDAL INPUT=SHAPEFILE

cat  o34084b1.wld
2.438400000000
0.000000000000
0.000000000000
-2.438400000000
763785.222415230000
3794653.234146172600

/usr/local/bin/gdalinfo o34084b1.tif
Driver: GTiff/GeoTIFF
Size is 5717, 6933
Coordinate System is `'
Corner Coordinates:
Upper Left  (    0.0,    0.0)
Lower Left  (    0.0, 6933.0)
Upper Right ( 5717.0,    0.0)
Lower Right ( 5717.0, 6933.0)
Center      ( 2858.5, 3466.5)
Band 1 Block=5717x6933 Type=Byte, ColorInterp=Palette  Color Table (RGB
with 256 entries)
   0: 0,0,0,255
   1: 255,255,255,255
   2: 0,151,164,255
<...snip...>

cat o34084b1.map
NAME  BufordDam
SIZE 600 600
EXTENT 763785.22241523 3794653.23414617 777725.55521523 3777747.80694617
SHAPEPATH "/var/www/html/maps/"
DEBUG on

WEB
 LOG "/tmp/buforddam.log"
 HEADER BufordDam_header.html
 TEMPLATE BufordDam.html
 FOOTER BufordDam_footer.html
 MINSCALE 1000
 MAXSCALE 1550000
 IMAGEPATH "/var/www/html/maps/images/"
 IMAGEURL "/maps/images/"
END

LAYER
 NAME "BufordDam"
 DATA o34084b1.tif
 TYPE raster
 STATUS DEFAULT
END #END OF LAYER
END # Map File

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