Co-registration of laser altimeter tracks with digital terrain models and applications in planetary science

2016 ◽

Vol XLI-B4 ◽

pp. 397-403

Author(s):

M. R. Henriksen ◽

M. R. Manheim ◽

E. J. Speyerer ◽

M. S. Robinson ◽

Keyword(s):

Digital Terrain Models ◽

Laser Altimeter ◽

Narrow Angle ◽

Digital Terrain ◽

Terrain Models ◽

Lunar Reconnaissance Orbiter ◽

Geomorphic Features ◽

Invaluable Tool ◽

Pixel Scale

The Lunar Reconnaissance Orbiter Camera (LROC) includes two identical Narrow Angle Cameras (NAC) that acquire meter scale imaging. Stereo observations are acquired by imaging from two or more orbits, including at least one off-nadir slew. Digital terrain models (DTMs) generated from the stereo observations are controlled to Lunar Orbiter Laser Altimeter (LOLA) elevation profiles. With current processing methods, digital terrain models (DTM) have absolute accuracies commensurate than the uncertainties of the LOLA profiles (~10 m horizontally and ~1 m vertically) and relative horizontal and vertical precisions better than the pixel scale of the DTMs (2 to 5 m). The NAC stereo pairs and derived DTMs represent an invaluable tool for science and exploration purposes. We computed slope statistics from 81 highland and 31 mare DTMs across a range of baselines. Overlapping DTMs of single stereo sets were also combined to form larger area DTM mosaics, enabling detailed characterization of large geomorphic features and providing a key resource for future exploration planning. Currently, two percent of the lunar surface is imaged in NAC stereo and continued acquisition of stereo observations will serve to strengthen our knowledge of the Moon and geologic processes that occur on all the terrestrial planets.

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EXTRACTING ACCURATE AND PRECISE TOPOGRAPHY FROM LROC NARROW ANGLE CAMERA STEREO OBSERVATIONS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xli-b4-397-2016 ◽

2016 ◽

Vol XLI-B4 ◽

pp. 397-403 ◽

Cited By ~ 1

Author(s):

M. R. Henriksen ◽

M. R. Manheim ◽

E. J. Speyerer ◽

M. S. Robinson ◽

Keyword(s):

Digital Terrain Models ◽

Laser Altimeter ◽

Narrow Angle ◽

Digital Terrain ◽

Terrain Models ◽

Lunar Reconnaissance Orbiter ◽

Geomorphic Features ◽

Invaluable Tool ◽

Pixel Scale

The Lunar Reconnaissance Orbiter Camera (LROC) includes two identical Narrow Angle Cameras (NAC) that acquire meter scale imaging. Stereo observations are acquired by imaging from two or more orbits, including at least one off-nadir slew. Digital terrain models (DTMs) generated from the stereo observations are controlled to Lunar Orbiter Laser Altimeter (LOLA) elevation profiles. With current processing methods, digital terrain models (DTM) have absolute accuracies commensurate than the uncertainties of the LOLA profiles (~10 m horizontally and ~1 m vertically) and relative horizontal and vertical precisions better than the pixel scale of the DTMs (2 to 5 m). The NAC stereo pairs and derived DTMs represent an invaluable tool for science and exploration purposes. We computed slope statistics from 81 highland and 31 mare DTMs across a range of baselines. Overlapping DTMs of single stereo sets were also combined to form larger area DTM mosaics, enabling detailed characterization of large geomorphic features and providing a key resource for future exploration planning. Currently, two percent of the lunar surface is imaged in NAC stereo and continued acquisition of stereo observations will serve to strengthen our knowledge of the Moon and geologic processes that occur on all the terrestrial planets.

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High Resolution Digital Terrain Models of Mercury

Remote Sensing ◽

10.3390/rs12233989 ◽

2020 ◽

Vol 12 (23) ◽

pp. 3989

Author(s):

Moritz Tenthoff ◽

Kay Wohlfarth ◽

Christian Wöhler

Keyword(s):

High Resolution ◽

Image Resolution ◽

Evaluation Methodology ◽

Iteration Step ◽

Altimeter Data ◽

Digital Terrain Models ◽

Reconstruction Procedure ◽

Laser Altimeter ◽

Digital Terrain ◽

Terrain Models

We refined our Shape from Shading (SfS) algorithm, which has previously been used to create digital terrain models (DTMs) of the Lunar and Martian surfaces, to generate high-resolution DTMs of Mercury from MESSENGER imagery. To adapt the reconstruction procedure to the specific conditions of Mercury and the available imagery, we introduced two methodic innovations. First, we extended the SfS algorithm to enable the 3D-reconstruction from image mosaics. Because most mosaic tiles were acquired at different times and under various illumination conditions, the brightness of adjacent tiles may vary. Brightness variations that are not fully captured by the reflectance model may yield discontinuities at tile borders. We found that the relaxation of the constraint for a continuous albedo map improves the topographic results of an extensive region removing discontinuities at tile borders. The second innovation enables the generation of accurate DTMs from images with substantial albedo variations, such as hollows. We employed an iterative procedure that initializes the SfS algorithm with the albedo map that was obtained by the previous iteration step. This approach converges and yields a reasonable albedo map and topography. With these approaches, we generated DTMs of several science targets such as the Rachmaninoff basin, Praxiteles crater, fault lines, and several hollows. To evaluate the results, we compared our DTMs with stereo DTMs and laser altimeter data. In contrast to coarse laser altimetry tracks and stereo algorithms, which tend to be affected by interpolation artifacts, SfS can generate DTMs almost at image resolution. The root mean squared errors (RMSE) at our target sites are below the size of the horizontal image resolution. For some targets, we could achieve an effective resolution of less than 10 m/pixel, which is the best resolution of Mercury to date. We critically discuss the limitations of the evaluation methodology.

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