Posted on June 4th, 2013

Astrium’s Elevation30 – A Near-Global Off-the-Shelf Elevation Data Solution

For many international engineering projects and academic studies, there is a need for:

  1. Reasonably priced elevation data that can be delivered in days – versus weeks or months for many products; and
  2. Elevation data with a resolution that exceeds that of the free sources, such as 90-meter USGS SRTM and 30-meter ASTER GDEM.
SPOT_Elevation30_comparisonClick on the image above to see an animated comparison of 20-meter Elevation30, 30-meter ASTER GDEM and 90-meter USGS SRTM data obtained over Poland. (Image Sources: USGS, JPL and Astrium)

In these instances, Astrium’s Elevation30 data product is the perfect solution with coverage of more than 123.3 million square kilometers (sq km) or roughly 90% of the world’s land minus Antarctica!

When ordered in a cartographic projection such as UTM, Elevation30 data is delivered as a GeoTIFF file with 20-meter resolution. That means you get more than two times the data with Elevation30 as compared to 30-meter GDEM rasters; and then more than 20 times the data as compared to 90-meter SRTM. Equipped with additional elevation data, you can produce more accurate hydrologic models, least-cost path analysis and slope-aspect calculations – saving you both time and money versus laborious field studies. In the animation below, we compare Astrium’s Elevation30 data to free SRTM and ASTER DEMs obtained over Poland – and it’s obvious that Elevation30 is a more accurate representation of the earth’s surface.

Elevation30 data is obtained by two 5-meter optical sensors mounted on the HRS instrument (High Resolution Sensor) on SPOT 5. These two sensors are mounted at 20 degrees off-nadir with opposing look angles so that they collect the stereoscopic imagery required to produce Elevation30. HRS collects stereo scenes that cover 72,000 sq km (600-km long x 120-km wide); meaning that if we do not have the coverage needed to produce Elevation30 data in-house, then tasking timelines are minimized.

Accuracy is an important consideration with any geospatial dataset, and Elevation30 data achieves a DTED Level 2 specification. Elevation30 accuracy specifications range from:

  • 15 to 30-meters for absolute horizontal accuracy (Circular Error 90%, CE90%)
  • 10 to 20-meters for absolutely vertical accuracy (Linear Error 90%, LE90%)
Elevation30 Coverage_april2012A coverage map of SPOT 5 HRS data availability as of December 2011, more than 122 million sq km are currently available. (Map Courtesy: Astrium)

Astrium is able to achieve these accuracies without the use of additional ground control which is a huge cost savings especially in regions of the world with limited access and/or unsafe conditions on the ground. The accuracy of Elevation30 increases as the size of the polygon ordered does; as well as with the availability of an Astrium Reference 3D layer from which supplemental control can be extracted. Elevation30 is a digital surface model (DSM) meaning that ground features such as vegetation and human made structures are present while the surface of water bodies are flattened.

Elevation30 data is priced by the square kilometer with volume and academic discounts available. For more information about Elevation30, contact your Apollo Mapping sales representative at (303) 993-3863 or sales@apollomapping.com.

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