Mapping Toolbox

tbase

TerrainBase global 5-minute digital terrain data extraction

Syntax

• [map,maplegend] = tbase(scalefactor)
  [map,maplegend] = tbase(scalefactor,latlim,lonlim)
  

Background

TerrainBase is a global model of terrain and bathymetry on a regular 5-minute grid (approximately 10 km resolution). It is a compilation of the best available public domain data from almost 20 different sources, including the DCW-DEM and ETOPO5. The model is currently under development and will be updated as new data sources become available. The dataset was created by the National Geophysical Data Center and World Data Center-A for Solid Earth Geophysics in Boulder, Colorado.

Description

[map,maplegend] = tbase(scalefactor) reads the data for the entire world, reducing the resolution of the data by the specified scale factor. The result is returned as a regular matrix map and an associated map legend.

[map,maplegend] = tbase(scalefactor,latlim,lonlim) reads the data for the part of the world within the latitude and longitude limits. The limits must be two-element vectors in units of degrees.

Remarks

Elevations and depths are given in meters above or below mean sea level.

The tbase.bin file is available on CD-ROM from:

• NOAA/NGDC
  Mail Code E/GC3
  325 Broadway
  Boulder, CO  80303
  USA
  Tel: (303) 497-6338
  Fax: (303) 497-6513
  

and via the Internet at:

• ftp://ftp.ngdc.noaa.gov/Solid_Earth/cdroms/TerrainBase_94/data/
  

No byte-swapping or line-ending conversion is required.

A summary of the model can be found at:

• ftp://ftp.ngdc.noaa.gov/Solid_Earth/Topography/tbase_5min/
      tbase.txt
  

Examples

Read every tenth point in the dataset:

• [map,maplegend] = tbase(10);
  whos
    Name              Size         Bytes  Class
  
    map           216x432       746496  double array
    maplegend       1x3             24  double array
  
  limitm(map,maplegend)
  ans =
     -90    90     0   360
  

Read data for Korea and Japan at the full resolution:

• scalefactor = 1; latlim = [30 45]; lonlim = [115 145];
  [map,maplegend] = tbase(scalefactor,latlim,lonlim);
  whos map
    Name      Size         Bytes  Class
  
    map     180x360       518400  double array
  

See Also

gtopo30	Read elevation data from GTOPO30
etopo5	Read data from the ETOPO5 dataset
usgsdem	Read USGS digital elevation maps

satbath

tgrline