8.5. Mars Global Surveyor MOC-NA

In the Stereo Pipeline Tutorial in Section 4.2, we showed you how to process a narrow angle MOC stereo pair that covered a portion of Hrad Vallis. In this section we will show you more examples, some of which exhibit a problem common to stereo pairs from linescan imagers: spacecraft jitter is caused by oscillations of the spacecraft due to the movement of other spacecraft hardware. All spacecraft wobble around to some degree but some are particularly susceptible.

Jitter causes wave-like distortions along the track of the satellite orbit in DEMs produced from linescan camera images. This effect can be very subtle or quite pronounced, so it is important to check your data products carefully for any sign of this type of artifact. The following examples will show the typical distortions created by this problem.

Note that the science teams of HiRISE and LROC are actively working on detecting and correctly modeling jitter in their respective SPICE data. If they succeed in this, the distortions will still be present in the raw images, but the jitter will no longer produce ripple artifacts in the DEMs produced using ours or other stereo reconstruction software.

ASP has its own jitter solver, which was shown to reduce the jitter for CTX (Mars) and DigitalGlobe (Earth) data (Section 16.38).

8.5.1. Ceraunius Tholus

Ceraunius Tholus is a volcano in northern Tharsis on Mars. It can be found at 23.96 N and 262.60 E. This DEM crosses the volcano’s caldera.

../_images/ceraunius_tholus_mocna_ge_combined.png

Fig. 8.3 Example output for MOC-NA of Ceraunius Tholus. Notice the presence of severe washboarding artifacts due to spacecraft jitter.

8.5.1.1. Commands

Download the M08/06047 and R07/01361 images from the PDS.

ISIS> moc2isis f=M0806047.img t=M0806047.cub
ISIS> moc2isis f=R0701361.img t=R0701361.cub
ISIS> spiceinit from=M0806047.cub
ISIS> spiceinit from=R0701361.cub
ISIS> cam2map4stereo.py M0806047.cub R0701361.cub
ISIS> parallel_stereo M0806047.map.cub R0701361.map.cub result/output

See Section 6 for a discussion about various speed-vs-quality choices. See Section 8 for other examples.