GEON IDV Mediterranean Topography; SRTM30+ data; click for larger |
The GEON Integrated Data Viewer - Contents
INTRO
Introducing the GEON IDV
INSTALL
Download & Run the GEON IDV
YOUR DATA Data Formats for the IDV |
Topography Data Sources for the GEON IDV
This page provides links to data that can be used to make topography displys using the IDV.
High quality topography data for the entire globe is available online ready to use in the IDV, in many cases simply by providing the URL to the data, with no need to copy data files.
The IDV can display topography data (gridded elevation values) as contours, flat surfaces colored by elevation value, and as 3D topographic relief maps which may be colored by elevation or be drapped with imagery. The colors and vertical exaggeration are adjustable. Surfaces may be below sea level, and displays may be in for any area and with many map projections including polar projections. You can also make a data transect of elevation showing a graph of elevation along a line.
You can drape TIFF and JPEG imagery over 3D relief topography. Any 2D grid values, for example, gravity anomaly grids, may be displayed on a map with the parameter value controlling the "Altitude" in a 3D relief plot.
SRTM and NOAA Coastal Relief Models
USGS DEMs
USGS ETOPO2 and "GLOBE" data
Sample IDV Topography Displays
Japanese bathymetry, 3D relief surface; oblique view, colored by elevation; 10 x vertical exaggeration; NGDC GLOBE data |
Mt St Helens (true vertical scale; elevation data is USGS hoquiam-e DEM, drapped with photography) | |
Arctic Basin Contours |
 topography data transect
|
SRTM-based Topography Data
Built into the IDV is direct access to the global SRTM topography data, using web map services.
In the IDV's Dashboard window, Data Choosers panel, Catalogs tab, set Catalogs: to http://www.unidata.ucar.edu/georesources/idvcatalog.xml. In the list click on Topography/Bathumetry to see more choices.
Three excellent choices are the "SRTM30+ Version 4.0 (30 src second - Worldwide)" the Smith and Sandwell v9.1 (~60 src second - Worldwide)," and the "NOAA Coastal Relief Models (3 arc second)." 30 arc-second is a resolution of 0.5 geographic minute or a little smaller than 1.0 km grid value spacing; 60 arc second data has twice that spacing (near 2 km or a little better), and 3 arc second is about 100 meter resolution.
To add this data in the IDV, click on the source you choose, and click "Add Source" in the Data Choosers panel. The data is not copied to the IDV at this point; you are only connected to the web map service.
If you try to add any of these complete data sets to the IDV and make a display, the IDV may be overloaded and basically freeze up, since the data sets are so large. To avoid this, subset the data you want as follows:
Subsetting by area:
In the Dashboard's "Field Selector" tab, above the little map, check OFF the "Use Default" box. In the box use a mouse pointer drag to make the area where you want the data. See this figure:
click for full size
Subsetting by Stride:
In the Dashboard's "Field Selector" tab, above the little map, click on Stride, then check OFF the "Use Default" box. Notice that the total grid size of the available data is shown, for excample "x: 21600 y: 17280" for the Smith and Sandwell 60 src second topo grid. Select how to subset the data by choosing, for example, "Every fifth point." That choice will reduce your data demand by 25.
You can subset by both methods if needed.
In the top of the Displays section click on the display type you want. Plan Views -> color image makes a flat color-filled image of the topography data colored by value; Plan Views -> Contours makes a flat map of contour lines. 3D Surface -> Topography makes a 3D relief surface colored by value.
Click "Create display." You may need to change the IDV Projection (area) to where your topography data is. For many data sets the IDV takes several seconds to display the data, espeically for 3D relief images.
Publications
SRTM30 documentation (pdf)
"SRTM30 is a near-global digital elevation model (DEM) comprising a combination of
from the Shuttle Radar Topography Mission, flown in February, 2000 and the
U.S. Geological Survey's GTOPO30 data set. ... Since the SRTM mission was only
able to map up to approximately 60.25 degrees north latitude [and 56 south], values above this point
are completely from GTOPO30. ... The geodetic reference for SRTM data is the WGS84 EGM96 geoid as documented
at http://earth-info.nga.mil/GandG/wgs84/gravitymod/index.htm."
SRTM30 data
SRTM3 North American data
SRTM30 PLUS (Scripps) Ocean bathymetry is based on the Smith and Sandwell global 1-minute grid between latitudes +/- 81 degrees.
Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings; Walter H. F. Smith and David T. Sandwell; Science 26 September 1997: Vol. 277. no. 5334, pp. 1956 - 1962
Sample GEON IDV Displays of SRTM Data
SRTM30 PLUS map colored by topography (California)
SRTM30 PLUS data, 3D relief surface, oblique view
NOAA_Coastal_Relief_Model_3_arc_sec_Vol_6_Southern_Calif: contour (250 m) map, plus colored relief (stride every 2nd point)
DEM Files
The IDV can read and display DEM files. Many of these are available online; see for example The National Map Seamless Server and . For Alaska see Alaska DEMS.
The USGS makes DEMs on many scales; see USGS Digital Elevation Models (DEM) and DV_sample_USGS_DEM_topography_3D_oblique_view_large.png USGS DEMs. See also USGS Geographic Data Download including 1,125000 scale (3 arc seconds) and higher resolution 1:24000 scale DEMs (resolution near 10 meters), and other topographic data. There are also 2 arc seconds DEMs; see 2-Arc-Second Digital Elevation Models
To find a USGS 1:250,000 DEM (100 m grid spacing; 1 square geographic degree area) for your area, first find the name of the USGS 1:250,000 topo map for the area, for example, using the web service USGS topo maps. Then find the USGS DEM file of the same name in this directory. These DEMs cover an area 1 degree on a side. For each topo map area and name, there are an east and west DEM. Download the file (about 1 MB); gunzip the file (to 9.83 MB). Add the "data source" file to the IDV -- use data type "DEM file." You can use it for any topo data display or purpose.
A sample DEM file from the USGS is http://geon.unavco.org/unavco//TOPO/hoquiam-e.dem for part of Washington state that includes Mt. St. Helens.
More sample USGS DEM files UGGS DEMs (most are 1:125000)
Scales and resolutions:
USGS 1:24000 scale DEMs (resolution near 10 meters)
USGS 2 arc-second DEMs (about 62 meters resolution horizontally; the unit of coverage is a 30- by 30-minute block, or 1 km on a side);
USGS 1:250,000-scale Digital Elevation Models
have a horizontal resolution of 3 arc-seconds: the spacing of the elevation values is 3 arc-seconds
(roughly 100 meters). The vertical resolution is the nearest integral meter at each grid location.
30 arc second or about 1 km grid point spacing (resolution).
2 arc minute or about 3 km grid point spacing.
4 arc minute or about 7 km.
5 arc minute or about 10 km.
IDV contours of USGS DEM "denver_w"
same data as in part of image above; click for larger size.
The USGS GTOPO30 data is a global digital elevation model (DEM) at 30-arc seconds (approximately 1 kilometer). GTOPO30 does not include bathymetry below the ocean surface. You can download tar files of 50 latitude by 40 degree longitude DEM files from ftp://edcftp.cr.usgs.gov/pub/data/gtopo30/global, but these GTOPO30 DEM files do not work in the IDV.
Some USGS topography data from the ETOPO2, ETOP05, and "GLOBE" data sets (not DEMs) have been made into netCDF files for the IDV.
Japanese bathymetry, 3D relief surface;
oblique view, colored by elevation;
10x vertical exaggeration; NGDC GLOBE data
These web pages have the topography files of the indicated resolution:
The file names give the region.
Just "copy link location" and enter that URL in the IDV Data Choosers URLs box.
7 km (4 minute) to (with bathymetry)
3 km (2 minute) (with bathymetry)
1 km (30 sec) (no bathymetry)
various
More Topographic Data Files for the GEON IDV Online
Cut and paste the URL into the IDV Data Choosers URLs entry box, or save the file to your local disk and enter its file path into the IDV Data Choosers Files entry box.
Topography grids of 30 second horizontal resolution (near 1 km),
not including seafloor; integer meters elevation values:
US, Alaska, western (52 to 72 N, 151 to 170 W): http://geon.unavco.org/unavco/TOPO/US_Alaska_west_GLOBE_30sec_topo.nc
US, Alaska, eastern (54 to 72 N, 130 to 151 W): http://geon.unavco.org/unavco/TOPO/US_Alaska_east_GLOBE_30sec_topo.nc
US, western (31 to 50 N, 114 to 129 W): http://geon.unavco.org/unavco/TOPO/US_western_GLOBE_30sec_topo.nc
US, Rocky Mountains (31 to 50 N, 104 to 114 W): http://geon.unavco.org/unavco/TOPO/US_Rockies_GLOBE_30sec_topo.nc
US, plains (24 to 51 N, 92 to 104 W): http://geon.unavco.org/unavco/TOPO/US_plains_GLOBE_30sec_topo.nc
US, midwest (24 to 51 N, 80 to 92 W): http://geon.unavco.org/unavco/TOPO/US_midwest_GLOBE_30sec_topo.nc
US, eastern (24 to 51 N, 67 to 80 W): http://geon.unavco.org/unavco/TOPO/US_eastern_GLOBE_30sec_topo.nc
Europe, 30 sec resolution, western (12W to 4E):
http://geon.unavco.org/unavco/TOPO/Europe_west_topo_30sec.nc
(click here to see Europe topo data area, all 3 parts)
Europe, 30 sec resolution, central (4E to 20E):
http://geon.unavco.org/unavco/TOPO/Europe_central_topo_30sec.nc
(click here to see detail of central Alps as 3D relief)
Europe, 30 sec resolution, eastern (20E to 35E): http://geon.unavco.org/unavco/TOPO/Europe_eastern_topo_30sec.nc
Other resolutions or areas:
US, 48 states, 4 minute horizontal resolution (near 7 km): http://geon.unavco.org/unavco/TOPO/US_topo_4min.nc
US, 10 minute resolution (near 18 km): http://geon.unavco.org/unavco/TOPO/US_topo_10min.nc
Europe, 2 minute horizontal resolution, including seafloor (data spacing <= 4 km):
http://geon.unavco.org/unavco/TOPO/Europe_topography_2min.nc
(click here to see 2 min. Europe topo data area)
Antarctica, 4 min. topography (south of 60 S, including seafloor) http://geon.unavco.org/unavco/TOPO/Antarctica_4min_topo_etopo2v2.nc
Arctic, 4 min. topography (north of 55 N, including seafloor) http://geon.unavco.org/unavco/TOPO/Arctic_topo_4min_etopo2v2.nc
Japan, 2 min. topography, including seafloor http://geon.unavco.org/unavco/TOPO/Japan_topography_2min.nc
Tonga-Fiji region, 2 min. topography, including seafloor
(click here to see area covered)
http://geon.unavco.org/unavco/TOPO/Tonga_Fiji_topography_2min.nc
More Sample IDV Topographic Displays and Data
Tonga - Fiji region topography, 3D relief oblique view, colored by elevation
Yellowstone National Park and Grand Teton National Park 1 km resolution, oblique view
data is
http://geon.unavco.org/unavco/NETCDF/YNP_GTNP_topography_30sec.nc
Colorado Front Range 3D Relief, 1 km resolution, oblique view
data is
http://geon.unavco.org/unavco/TOPO/FrontRange_north_topography_30sec.nc
California, 2 minute resolution, oblique view
data is
http://geon.unavco.org/unavco/NETCDF/California_topography_2min.nc
European topography, 2 minute resolution, overhead view
and
the Alps, 2 minute resolution, overhead view
data is http://geon.unavco.org/unavco/TOPO/Europe_topography_2min.nc
Japan, 2 minute resolution, oblique view
data is
http://geon.unavco.org/unavco/TOPO/Japan_topography_2min.nc
Click on an image below to see full size.
Antarctica, 500 m contours (click to see full size image)
Topography of New York State colored by elevation
3D relief of Mt St. Helens with satellite photo draped over the surface;
Topography of Antarctica colored by elevation.
Topography of Arctic basin, oblique 3D relief, colored by elevation (and North pole!).
(NGDC 30 second "GLOBE" data). Click to see full size image.
vertical exaggeration is 1:1 (USGS DEM data). Click to see full size image.
Click to see full size image.
(NGDC ETOPO2v2 data)
Click to see full size image.
(NGDC ETOPO2v2 data)
Arctic basin, 500m contours (click to see full size image)
