Key PointsĬreating a mosaic of images of planetary surfaces is relatively straightforward in theory: Geometric data of the camera and spacecraft tell us where and how images should be placed relative to each other.
While the workflow developed for this product is applicable to other planetary bodies, it requires a reference source, which may not yet exist. We describe how the process works, which uses a reference source to tie brightness values, and demonstrate its effects across Mars' surface. We have developed a method, based on previous work by other researchers for other data sets, to mitigate almost all brightness variations between images in order to create the appearance of an evenly illuminated, practically seamless mosaic. These changes, along with an aging detector, prevent easily equalizing images to create a visually smoothly illuminated product from CTX images. Seasonal effects and transient phenomena affect atmospheric transparency. During that time, Mars has gone through nearly seven of its own years, changing solar distance from 1.38 to 1.67 AU and the corresponding solar flux by 45% due to its orbital eccentricity. The Context Camera (CTX) on MRO has returned over 115,000 images of the planet at approximately 5–6 m per pixel, providing nearly global coverage. The Mars Reconnaissance Orbiter ( MRO) spacecraft has been in orbit around Mars since March 2006.
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