[Mapserver-users] MapServer/gdal doesn't like Photoshop tiff

[Marvin Humphrey]

Perry,

Thank you, adding the properly formatted tfw file to the raster 
directory restored the image to the example.

Even better, the information you supplied me enabled me to hack up a 
TFW file for the GLOBE data and successfully bring that into MapServer, 
based on header files downloaded from here...

http://www.ngdc.noaa.gov/seg/topo/report/s11/s11B.html

It struck me that the data in a TFW file would be inadequate for 
representing projected data accurately -- which  pixel in an Albers 
Equal Area Conic projection do you use to define the x and y widths?  
Then I did a little more research and found that GeoTIFF contains a lot 
more than the simple TFW file.  How much distortion am I likely to see 
when I use a TFW instead of a precisely specified projection system?  
Will there be any for the LatLong GLOBE data, or am I inventing a 
problem where none actually exists?  I can't quite wrap my brain around 
the  3 dimensional visualization I need to figure it out. It looks like 
Lake Superior is in the right place more or less at this scale, but 
when I get down to the city level things could be off...

-- Marvin Humphrey

On May 18, 2004, at 11:42 PM, Pericles S. Nacionales wrote:

> This happens because photoshop doesn't support GeoTIFF images.  When 
> you
> open the GeoTIFF image in Photoshop and then save it again, you lose 
> the
> georeferencing.  What you can do to fix it is create what's called a
> world file.  This is a small text file with the following lines (this 
> is
> only valid for the example 1.5 image):
> 0.00473306
> 0.0
> 0.0
> -0.00473306
> -97.3743368
> 49.415919
>
> If you copy these lines to a text editor and save the file as
> mod09a12003161_ugl_ll_8bit.tfw in the same directory where you have 
> your
> tiff image, your map should then work.  To explain the lines briefly:
> line 1 represents the X dimension of your pixel (in map units)
> I don't really know what lines 2 and 3 are (don't change it unless you
> know what you're doing)
> line 4 is the negative Y dimension of your pixel (it has to be 
> negative)
> line 5 is the upper left X coordinate of the image
> line 6 is the upper left Y coordinate of the image
>
> You can get these info if you have the GDAL utility program "gdalinfo".
> Go ahead and use photoshop to edit the images but make sure to get the
> pixel dimensions and upper left coordinates of the image before doing
> so.
>
> Good luck!
> -Perry