|4-m posting DTM + Stereo or Tristereo pair|
|Method||DTM generated by automatic filtering of DSM produced from Pleiades stereo imagery, complex areas are completed by manual stereo editing,|
Pleiades Stereo pair(s),
Level Primary Regular, Format DIMAP JPEG2000
Cloud coverage < 5%
(Where cloud appears in the source images ,it will not be possible to calculate terrain elevation values)
|Available Option||Orthomosaic 50cm - Contour lines 5m|
|Projection||Geo WGS84 or UTM / WGS84 (custom projection on request).|
|Vertical reference||Elevations above mean sea level (ref. = EGM96).|
|Accuracy level||The accuracy specification of Elevation4 (with GCPs) is similar to the HRE40 NGA classification.|
It is recommend that 5 GCP’s distributed across each stereopair are recommended to reach a metric accuracy level.
|Metadata||No additional metadata is provided with the DTM.|
GeoTerrain 4 DTM will provide very good results where a high percentage of the ground is visible on the imagery. While areas that have a high percentage of ground that is obscured by above ground features, such as buildings & trees, where the DTM will be interpolated from surrounding areas of visible ground, will not be as detailed. In cases where the ground is continuously obscured for large areas, it will not be possible to generate GeoTerrain4. Areas of clouds (and their shadows) will be masked to NoData in the DTM as ground elevations cannot be computed.