MEX HRSC Digital Terrain Map Reduced Data Record (DTMRDR)

DTMRDR – Digital Terrain Map Reduced Data Record

Instrument: High Resolution Stereo Camera

PDS Data Set ID: MEX-M-HRSC-5-REFDR-DTM-V1.0

DOI: Mars Express DOI Overview Page

For more information about HRSC DTMRDR products, see the DTMRDR Product EAICD.

The High Resolution Stereo Camera (HRSC) Digital Terrain Map Reduced Data Record (DTMRDR) data products are 8-bit orthoimages for the Nadir channel and the 4 color channels and 16-bit DTMs (1 m numeric height resolution). The orthoimages are based on the DTMs, and are thus available exclusively for areas covered by the DTMs.

DTM generation is based on multi-image matching using pyramid-based least-squares correlation after pre-processing by adaptive (variable bandwidth) Gaussian low pass filtering of the stereo images to reduce the effects of image compression. 3D Point determination by least-squares forward intersection is followed by DTM grid interpolation (distance weighted averaging within a local interpolation radius). The overall process involves automatic procedures in combination with standardized quality checks. DTM generation uses adjusted orbit and pointing data.

The DTM and the adjusted orientation data are finally applied for orthoimage production. The only additional pre-processing step for orthoimages consists of a histogram-based linear contrast stretch which does not affect the linear metrics of the radiometric image calibration.

Based on the high-resolution DTM result, the quality of co-registration with the Mars Orbiter Laser Altimeter (MOLA) DTM is evaluated, and final improvements to the exterior orientation data are derived.

DTMRDR data products are processed by software which performs the following steps:

  • Remove all transmission headers to get the original camera data

  • Sort camera data by sensor and combine them with the housekeeping data

  • Decompress the data

  • Radiometric calibration of the data

  • Calculate footprints of every image file

  • Geometric calibration and map projection

  • Improvement of orbit and attitude data

  • Generation of Digital Terrain Models and Orthorectification of image data

HRSC DTMRDR products have the following file names:

Hnnnn_mmm_dd4.IMG

where:

nnnn = 4-digit orbit number

mmm = number of the image in this orbit

dd = sensor name

ND = nadir

BL = blue

GR = green

IR = near IR

RE = red

DT = DTM referenced to Mars sphere

DA = DTM referenced to Mars aeroid

4 = indicates the level of processing which is archived in PSA/PDS

In ODE, DTMRDR products have the following Product IDs:

HNNNN_MMM_DD4.IMG