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Post on 18-Jan-2016
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Quadrilateral Data Structure
Geodetic latitudeand longitude onGRS80/WGS 84ellipsoid(NAD 83)
Grid cell resolutionconstant N-S butprogressively finer E-W resolution fromequator to pole
ETOPO5 Global Digital Elevation Model
ETOPO5 Digital Elevation Model(DEM)
Row Major Order
World Map (left) made from World Map (left) made from ETOPO5 DEMETOPO5 DEM
ETOPO2 Global DEMfrom National Geophysical Data Center
Piece of a World Map Piece of a World Map made from ETOPO2 DEMmade from ETOPO2 DEM
Worldwide Land And Worldwide Land And Sea Elevation DataSea Elevation Data
In MetersIn Meters(3.7x3.7km cells at equator)(3.7x3.7km cells at equator)
Technical Specifications(0,0) (10799,0)
(0,5399) (10799,5399)
Row Major Order
))
Technical Specifications(0,0) (10799,0)
(0,5399) (10799,5399)
2-byte signed integer data5400 rows by 10800
columns116,640,000 byte dataset
Row Major Order
ETOPO1 Global DEMfrom National Geophysical Data Center
Worldwide Land And Worldwide Land And Sea Elevation DataSea Elevation Data
In MetersIn Meters(1.85x1.85km cells at equator)(1.85x1.85km cells at equator)
Technical Specifications(0,0) (21599,0)
(0,10799) (21599,10799)
Row Major Order
Technical Specifications(0,0) (21599,0)
(0,10799) (21599,10799)
Row Major Order
2-byte signed integer data10800 rows by 21600
columns466,560,000 byte dataset
Map made from ETOPO1 dataMap made from ETOPO1 data
Globe 30” x 30” grid cell data structure and tiling, format, and dataset size
Alaska Map Made From Globe Data
STRM30 Plus
Map madeFrom CoastalRelief Model
National Elevation Dataset (NED)
One-second Grid For All U.S. States except…
Two-second Grid For Alaska
National Elevation Dataset (NED)Data Format and Tiling Scheme
Web Mapping Using NED 1” x 1” Data
National Elevation Dataset (NED)
1/3rd and 1/9th second Grids For Certain Areas
1/3rd Second Maps for Monterey
1/3rd Second Maps for Monterey
Ordering SRTM Data
Data Products
Shuttle Radar Topography Mission (SRTM)
SRTM Data Completeness Problems
Map Projection-basedRaster Data
USGS 7.5’x7.5’ 10m DEMs for Oregon
USGS 7.5’x7.5’ 10m DEMs for Oregon
Available only inSDTS Format
USGS 1:24000-scale Digital Raster
Graphics (DRG)
scanned topographic maps of U.S. states
and territories
Scanned at250 dpi
USGS 1 km Global Land Cover Characteristics database (GLCC)
Classified 1km x 1 kmAVHRR satellite data
Gridded on Interrupted Goode
Homolosine and Lambert Equal Area Map Projection Surfaces
Now in 30 arc second Quadrilateral Form
Several Land CoverClassification Systems Used
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