Digital Elevation Models (DEMs) from Satellite Imagery

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Numerous satellites are able to acquire stereo imagery, allowing LAND INFO to create Digital Elevation Models (DEMs) and contour data on a global basis. High-res (50cm – 1m) stereo satellite imagery is ideal for site-specific projects requiring the highest level of accuracy and details. Medium-resolution satellite stereo imagery such as SPOT-6 1.5m, ALOS 2.5m and ASTER 15m is more affordable for large-area coverage. Radar imagery fulfills a unique need in being able to map high cloud-cover tropical areas where optical imagery coverage would prove difficult.

LAND INFO offers multiple DEM options, including coverage we custom create from stereo pairs and DEMs produced directly by satellite operators DigitalGlobe and Airbus. DEM data purchased directly from the satellite operators is less expensive and has less cloud cover risk, where as DEMs custom-produced by LAND INFO offer the greatest flexibility.

The ability to create Digital Terrain Models (DTMs) in addition to Digital Surface Models (DSMs) will vary based on the ground cover of the area in question.

In areas where in-line stereo isn’t available, LAND INFO may be able to offer multi-view photogrammetry from overlapping satellite scenes as a faster and less expensive alternative.

Please contact LAND INFO for info regarding the differences between autocorrelation and photogrammetric methods.
  digital elevation model (DEM) of Rapa, French Polynesia

A digital elevation model (DEM) of Rapa, French Polynesia, photogrammetrically derived from IKONOS stereo satellite imagery.

The digital terrain model was used to orthorectify QuickBird imagery (shown partially draped on top of the DEM).

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Please note the options below for DEMs from satellite operators DigitalGlobe and Airbus are for the elevation data only, an additional charge applies for the imagery (which can be ortho mosaicked using the DEM.) For customers not able to supply their own GPS GCPs (Ground Control Points) LAND INFO is typically able to coordinate with a local land surveyor. Minimum order is 100 km2:

DigitalGlobe AES (Advanced Elevation Suite):
Product         Type GCPs Resolution Relative Accuracy Absolute Accuracy $ /km2
VHP DSM required 2m 1m 2m 55
VHP DTM required 2m 1m 2m 60
Precision DSM required 4m 2m 4m 25
Precision DTM required 4m 2m 4m 35
Mapping DSM optional 8m 5m 8m 15
Mapping DTM optional 8m 5m 8m 25

Accuracies listed are vertical (Z), LE 90. Uplifts apply for hydrology enforcement, road flattening and premium geographies (SE Asia, North Korea, China, Taiwan and Russia). Note that VHP and Precision products require GPS GCPs (Ground Control Points) to be supplied by the customer (specifications to be confirmed by LAND INFO); DTMs are only offered in open areas, not heavily vegetated or urban.

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Airbus Elevation1 and Elevation4 DSMs:
Product         Type Resolution $ /km2
Elevation 1 Stereo DSM 1m $92.00
Elevation 1 Stereo DTM 1m $103.50
Elevation 1 Stereo DSM & DTM 1m $115.00
Elevation 4 Stereo DSM 4m $46.00
Elevation 4 Stereo DTM 4m $57.50
Elevation 4 Stereo DSM & DTM 4m $69.00

Accuracies listed are vertical (Z), LE 90. Customer-provided GCPs can be used for no additional cost – accuracies above presume the use of GCPs otherwise LE 90 vertical accuracies with Ref3D GCPs are 6 to 10m, without GCPs up to 10m. Actual DEM accuracy will vary based upon several factors, including terrain, ground cover and GCPs. With GCPs Elevation4 is compliant to HRE40 NGA standards, Elevation 1 HRE10. Elevation1 DSMs in urban areas require a custom quote, production is not suitable for high vegetation areas. DTMs are only offered in more open areas where ground visibility is not overly obscured by buildings and trees. Cloud/cloud shadow areas are masked to NoData.

If suitable stereo imagery isn’t already in archive, acquisition time typically starts with a 2 month window. LAND INFO custom DEMs are more expensive than the options listed above but are the best solution for select areas/project types; please submit your area of interest along with a project description to receive a detailed recommendation.

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Related Pages:
Examples of Digital Elevation Models (DEMs)

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