USGS Digital elevation Models (DEM)
The following message was distributed to the GISList discussion group by TC Herman, Executive Vice President, The GeoCommunity on Friday, July 27, 2001. The message is in response to a number of requests for information regarding changes in the formatting of DEM data developed by the USGS.
GISList - Outlined below are some of the known differences/notes regarding pre and post
jan2001SDTS DEMs according to the USGS:
1)The Profile Identification PRID subfield in the xxxxIDEN.DDF:
pre jan2001 have PRID of "SDTS RASTER PROFILE"
post jan2001 have PRID of "SRPE: RASTER PROFILE and EXTENSIONS"
2)Data type for CEL0 values of SDTS DEMs:
pre jan2001 z-units were in feet or meters .....data type BI16.
post jan2001 z-units can be feet, meters or decimal meters....
data type can be BI16 (feet or meters)
or BFP32 (for decimal meter)
B. Only the most recent Sol Katz sdts2dem/sdtsedem .exe's will work on the SDTS decimal
C. ArcView 3.2 and ERDAS Imagine 8.4 do not recognize PRID of SRPE: RASTER
PROFILE and EXTENSIONS as a valid SDTS Profile. There is no problem with
ArcInfo8 and ArcView8...ArcToolbox works OK.
The ArcView3.2/ERDAS workaround requires editing the xxxxIDEN.DDF with
D. DLGv32 does not display SDTS decimal meter DEMs correctly...color
stretch/z values goofed up.
E. Software vendors that support the new SDTS DEMs with z-units of feet,
meters, and decimal meters:
ArcInfo 8, ArcView 8 via ArcToolbox.
ArcView3.2 (requires editing of xxxxIDEN.DDF)
ERDAS Imagine 8.4 (requires editing of xxxxIDEN.DDF )
If you develop DEM related products, scripts, extensions, or translators and would like to make them available to the public,
please send e-mail to firstname.lastname@example.org