5 Global elevation data comparisons of DLR, ASTER Gdem, SRTM3, GMTED2010, etc.

There are a variety of global elevation data on the Internet, domestic in this area is also gratifying, resources third has been put out of the Guardian film has given a lot of surprises, its elevation number is worth looking forward to. But the elevation data of resource third will have to wait, the past two or three years the global elevation data development is quite rapid, the DLR released a very high precision data, the end of last year Aster Gdem released a revised second version, data quality improvement is very big, yesterday saw netizens introduced the gmted data released by the USGS, So decided to wait for the domestic data, the current several global elevation data precision for a simple comparison.

First of all, the following five kinds of data: 1, DLR's SRTM X-band data: DLR is the German Aerospace Center abbreviation, 2000 in the Space Shuttle endeavour to carry out the SRTM (Space Shuttle Radar Topographic mapping task), the Germans ride their car also use their own radar surveying the global terrain data, The DLR uses a higher-precision radar test (X-band), which results in higher accuracy than the American (C-band), but only a mesh coverage of the global (that is, some places without DLR data) elevation data. In 2011, the Germans released this data download, the accuracy of 1 seconds (1 arc second), elevation relative accuracy of 6 meters, absolute accuracy of 16 meters. Here you can download: https://centaurus.caf.dlr.de:8443/eoweb-ng/index2.html.   This data is a bit more, the Germans are now carrying out more accurate topographic mapping task (Tandem-x, terrasar-x double Star observation) to measure the world's more accurate data, this time is covering the world, this data for civilian is considerable. 2, Aster gdem data: American goods,the data is based on observations made by NASA's new generation of ground observation satellite Terra. Its data coverage ranges from north latitude 83° to south latitude 83° to all land areas. This is currently the most widely-covered high-precision global elevation data. 2009 released the first version of the data, currently the Chinese Academy of Sciences has mirrored data can be downloaded. 3, GDEM-V2 data: To the previous Gdem data correction, released in October 2011, I was on the Japan Space Agency's website downloaded. 4, SRTM C-band data, American goods, may be the most well-known elevation data. NASA's radar observations from the Space Shuttle Endeavour at 2000 were the most used elevation data, covering 60 degrees south of the globe. There are two kinds of SRTM1 and SRTM3, that is, 1 angular seconds and 3 angular second precision data, corresponding precision of 30 meters and 90 meters. The elevation data used by Google Earth is SRTM3. The publicly available coverage of the Chinese area is only 90 meters in accuracy. CAS image can be downloaded. 5, GMTED2010 Data, American Geological Survey USGS and the United States National Geospatial Intelligence Agency NGA, I just know this data. from its readme file, it is a further optimization and development of the USGS GTOPO30, but this data accuracy is not significant, only 30 seconds, 15 corner seconds and 7.5 corner seconds, the corresponding maximum precision is 250 meters. A few more words: The USGS has it do only cover the United States elevation data, see its introduction, precision is 1 seconds of 1/3 corner seconds, part of the region also has 1/9 corner seconds, that is, the accuracy of 3 meters level, quite impressive. All I'm concerned about is Chinese data, except that the DLR is open to high-precision, as previously stated, there are often more accurate data in the United States than in China, and ordinary users are not getting the higher-precision data in the Chinese region.     I use the data in the Xiangshan district of Beijing to compare, with a point distance of 5 meters to intercept the region's various raw elevation data (the interception accuracy is greater than the original data accuracy, so interception will not produce distortion). There are several kinds of gmted data, not yet see the specific difference, I use the gmted-gmax075. contrast one: The scale is not strictly controlled, the scale of 5 kinds of data is basically about 1:57,000, the picture is about 15 kilometers long, the west to the military Zhuang town, Dongzhi Summer Palace.




contrast two: The scale is in 1:12,000, compared to the details, the generation of 10 meters high-distance contour to assist the display of details, the lower right corner of the blue area is Xiangshan reservoir, can be used as a reference, the reservoir length of about 500 meters. You can see that the details of the DLR are very rich and the availability is quite strong.   



Basic Conclusion: The DLR accuracy of 10 meters (relative accuracy of 6m, absolute accuracy of 16m), gdem-v2 in about 30 meters, Gdem and SRTM in 90 meters or so, GMTED2010 in 200 meters. so for those who only want to use as high-precision data as possible, and do not want to spend too much time to study the differences between the users, my suggestion is to download all the DLR data and GDEM-V2 data, the DLR coverage of the area with DLR data, not covered by the area with Gdem-v2.

5 Global elevation data comparisons of DLR, ASTER Gdem, SRTM3, GMTED2010, etc.