10 METER DIGITAL ELEVATION MODEL
==================================
COVERAGE NAME: DEM10_ME1
FEATURE TYPE: RASTER Arc/Info GRID format
SOURCE: USGS DeciMeter Digital Elevation Models
MINIMUM MAPPING UNIT: 10 meters (spatial resolution)
AREAL EXTENT: Gualala River Basin Hydrologic Units as defined by Calwater v2.2n
DATE OF LAST UPDATE: 3/6/2000
INFO ITEMS:
INPUT OUTPUT DATA DECI DESCRIPTION
ITEM NAME WIDTH WIDTH TYPE MALS
---------- ----- ------ ---- ---- ------------------------------------
VALUE 4 10 B the elevation in meters (z=10)
COUNT 4 10 B the number of cells with that value
METHODS:
10 meter DEMs were merged together from Quads. Seamlines were then filtered
out and sinks were filled.
The Z Value is 10. These are decimeter precision DEMs, so to save space, the
elevations were mulitplied by 10 to create an integer GRID that would preserve
the precision of the data.
CONTACT: Eric Spry, GIS Specialist
CDF Fire and Resource Assessment Program
1920 20th Street, Sacramento, CA 95814
eric_spry@fire.ca.gov
COORDINATE SYSTEM DESCRIPTION
Projection ALBERS
Units METERS Spheroid CLARKE1866
Parameters:
1st standard parallel 34 0 0.000
2nd standard parallel 40 30 0.000
central meridian -120 0 0.00
latitude of projection's origin 0 0 0.000
false easting (meters) 0.00000
false northing (meters) 0.00000
ADDITIONAL PROCESSING NOTES:
Although the USGS DEM specification indicates that each posting is a floating point number, in most cases these have been rounded to the nearest integer. Therefore these lattices are stored as integers rather than floats, reducing storage requirements significantly. The DEMs were imported with the INT option.
Because changing the projection of a grid requires resampling that can cause edge-matching problems, the DEMs have been left in their original projection, which is UTM zone 10 (west of longitude -120) or 11 (east of longitude -120). The best procedure for changing the projection is to merge adjacent grids first, then re-project. The most appropriate re-sampling methods are either bilinear interpolation or cubic convolution. Don't use the default nearest neighbor.
DOCUMENTATION DATES:
October 2002: Reprojected to UTM NAD27 (no shift), Z Value reset to 1, and clipped to KRIS project study area.
Contact Name: P. J. Trichilo
Institute for Fisheries Resources (IFR)
791 Eighth Street Ste. N
Arcata, CA 95521
Contact's Phone: (707) 822-9428