The 75 cm and 35 cm global Stereophotoclinometry (SPC) Digital Terrain Models (DTMs) were generated in 2016 using the flight-like image suite of shape 4. These SPC DTMs were generated “in the blind” without user access to shape 4 to simulate a mission environment were the true shape of asteroid is unknown. The procedures used to generate these DTMs are the same as those for the the Origins, Spectral Interpretation,  Resource Identification, and Security--Regolith Explorer (OSIRIS-REx) mission. The format of these DTMs is an ICQ, which is the same as the archived shape 4. Both models represent a radius value roughly every 70 cm horizontally across the surface.

Purpose of these DTMs

These DTMs were compared against shape 4 to determine the 3D root mean squared (RMS) accuracy of the SPC solution.  This value can be obtained after a displacement of the center of the DTM to the center of shape 4. The 75 cm SPC DTM has a 3D RMS of 13 cm, and the 35 cm SPC DTM has a 3D RMS of 10 cm. Both of these values are better than the mission requirements, showing that SPC can be met mission requirements. Further details of the comparison between these DTMs and shape 4 can be found in Weirich et al., (2021).

These DTMs can be compared against shape 4 for additional analysis of the accuracy of the SPC technique.

These DTMs can also be compared against DTMs generated using different SPC procedures that are suspected to generate more accurate radius values.

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75 cm DTM - Global

This model is named after the ground sample distance (GSD) of the SPC maplets used for navigation of the spacecraft. Higher resolution maplets were generated to improve the quality of the 75 cm maplets. This DTM was generated with images that simulated the Approach and the Preliminary Survey stages of the OSIRIS-REx mission.  This model has a radius value roughly every 70 cm horizontally across the surface.


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35 cm DTM - Global

This model is named after the ground sample distance (GSD) of the SPC maplets used for navigation of the spacecraft. Higher resolution maplets were generated to improve the quality of the 35 cm maplets. This DTM was generated with images that simulated the Approach, Preliminary Survey, and Detailed Survey stages of the OSIRIS-REx mission.  This model has a radius value roughly every 70 cm horizontally across the surface.