DEM Elevation data

[William E Reid]

Jerl,



	I have only used geotiffs that I have made.  They are geotiff/TAB 
format.  But your LAYER should be very simple as far as  I know.  This 
worked for me....

         LAYER
           NAME "geotiff"
           TYPE RASTER
           STATUS ON
           DATA "geotiff/65729931.tif"
         END


All the magic (aside from the wonderful things mapsserver does for 
us...) is stored in the TIF or TAB depending on what type of geotiff you 
have.

You should be able to run 'gdalinfo <file.tif>' on the tif file and it 
should reveal coordinates stored in the tif (or accompanying tab file).

Be sure to read the man page on gdalinfo.....

gdalinfo --formats

will show you what formats are supported (ie. did I forget to compile in 
geotiff support....?)

Make sure your extents are set to display what is in the tiff ( are you 
looking at it on the currently displayed map, or are you looking at a 
peiece of farm equipment?  You extents need to encompass the tiff or 
part of it...)

$ gdalinfo 65729931.tif
Driver: GTiff/GeoTIFF
Size is 300, 3300
Coordinate System is:
GEOGCS["NAD83",
     DATUM["North_American_Datum_1983",
         SPHEROID["GRS 1980",6378137,298.2572221010042,
             AUTHORITY["EPSG","7019"]],
         AUTHORITY["EPSG","6269"]],
     PRIMEM["Greenwich",0],
     UNIT["degree",0.0174532925199433],
     AUTHORITY["EPSG","4269"]]
Origin = (-78.083333,37.000000)
Pixel Size = (0.00027778,-0.00027778)
Metadata:
   TIFFTAG_SOFTWARE=IMAGINE TIFF Support
Copyright 1991 - 1999 by ERDAS, Inc. All Rights Reserved
@(#)$RCSfile: etif.c $ $Revision: 1.9.1.3 $ $Date: 2002/07/29 15:39:06EDT $
   TIFFTAG_XRESOLUTION=1
   TIFFTAG_YRESOLUTION=1
   TIFFTAG_RESOLUTIONUNIT=1 (unitless)
Corner Coordinates:
Upper Left  ( -78.0833333,  37.0000000) ( 78d 5'0.00"W, 37d 0'0.00"N)
Lower Left  ( -78.0833333,  36.0833333) ( 78d 5'0.00"W, 36d 5'0.00"N)
Upper Right ( -78.0000000,  37.0000000) ( 78d 0'0.00"W, 37d 0'0.00"N)
Lower Right ( -78.0000000,  36.0833333) ( 78d 0'0.00"W, 36d 5'0.00"N)
Center      ( -78.0416667,  36.5416667) ( 78d 2'30.00"W, 36d32'30.00"N)
Band 1 Block=300x6 Type=Float32, ColorInterp=Gray


Hope that helps.

-=Bill


Jerl Simpson wrote:
> Would you mind sharing your LAYER definition?  I have the file, but
> can't seem to get it to display properly.  It's scale is wrong or
> something and I can't get it worked out.  I see the layer, but can't
> really tell what I'm looking at.
> 
> I appreciate it.
> 
> jerl
> 
> On 6/14/05, William E Reid <wer at cstone.net> wrote:
> 
>>Just My 2 cents on the Subject.
>>
>>DEMs are no longer readily available from places like usgs.  I am not
>>really sure why.  They are the easiest to work with (ie convert).
>>
>>If you are in the States....
>>
>>at http://seamless.usgs.org you can download 3arc and 1arc second
>>terrain data.  It comes in ArcGrid Format.  Though I have not seen a way
>>to do this, I will be looking to convert them to geotiffs and shape
>>files and dems with less granularity.
>>
>>A geotiff loads quickly and gives the best performance in mapserver
>>(from my experience anyway) if you are just looking to make things look
>>more interesting.
>>
>>Actually, you can download the data in Geotiff format, which is what I
>>would recommend....  These might be more then what you want for
>>granularity, I only dealt with 3arc and above data.
>>
>>National Elevation Dataset.  I love em.
>>
>>Your Tiff? Make sure it is a geotiff.  It needs to know where it is on
>>the map.  If you disable TRANFORM (set it to false) in your layer it
>>will probably show up.  But it needs to be a geotiff to show up properly.
>>
>>Hope that helps.
>>
>>-=Bill
>>
>>
>>Jerl Simpson wrote:
>>
>>>Hi guys,
>>>
>>>I am wanting to add DEMs or some elevation/contour maps to my maps.
>>>But I am curious what works best with Mapserver.  I have found several
>>>different resource, but am at a loss as to which one I need.
>>>
>>>The first one I tried, which was to download JPEG images and convert
>>>them to TIFF images, never actually show up as a layer.  This may be a
>>>format issue on my part.  I haven't dug into that yet.
>>>
>>>I found one that is a ETOPO2 Global 2-Minute Gridded Elevation Data.
>>>But I don't know what that is and not sure if it can be used.  If
>>>someone knows a trick, I'd be please to find out.
>>>
>>>Similar issue with GLOBE files from NOAA.  Not sure if I can convert
>>>them to a format that's useful to use with Mapserver.
>>>
>>>I'm sure there are other options, I just haven't found them.
>>>
>>>I appreciate any help anyone might be able to give.
>>>
>>>Thank you,
>>>
>>>Jerl
>>>
>>
>>
>