TVC’s are an interim product of the USGS DEM production system. In providing these TVCs, the USGS nor the AGRC expresses no warranty or guarantee that they meet any standard for accuracy or completeness. Overall consistency may vary across the entire set of TVCs. A general rule is that a TVC will contain about 98%+ of the data found in a Standard DLG hypsography file. For fiscal year 2006, the USGS and the AGRC has not identified any resources to repair or improve any of the TVCs found deficient.
Normally, TVCs are in UTM coordinates but users should be aware other coordinates systems may have been used.
All contour elevations are in the same vertical datum as the published quadrangle map. Most TVCs' elevations are in feet, although some are in meters. Almost always, the contour elevations will be the same as the elevations on the published quadrangle map.
The TVCs collected here date from 1992 up to September of this year. Not all TVCs produced have been retained. Some TVCs may have multiple versions because of production requirements where a TVCs may have been produced for 30 meter DEM and then later for a 10 meter DEM, thus requiring more content detail or attribution.
TVCs have varying levels of quality, accuracy and completeness, and use various attributing schemes. TVCs are in some form of the DLG-optional format, however file headers may be incomplete or inaccurate. Most of the TVCs were produced in the datum of the quadrangle map used, but in some cases, the TVCs have been converted from North American Datum of 1927 (NAD27) to the North American Datum of 1983 (NAD83). For data on NAD83, the geographic footprint is NAD27. TVCs are not edge joined, and most TVCs do not have neatlines.
For questions, please contact one of the following individuals.
Mike Kling
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573-308-3732
Dan Daniels
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303-202-4401
Rusty Grout
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303-202-4484
Users' Comments
Display 1 of 1 comments
1.
Thu, 11-13-2008 at 08:36 AM
I keep getting the following error message when I try to open "Importing and converting TMV files".
FILE NOT FOUND: images/sgidraster/
importingtvc.html You are not authorised to view this resource.
I can see and download the data, but can't get this document to open for me. Can you help? Thanks.
