科研之友
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摘要
The analysis of crater size-frequency distributions (CSFDs) is a widely used technique to date and investigate planetary surface processes. There are two well-established crater measurement techniques, traditional crater counting and buffered crater counting, and two new geometric corrections, nonsparseness correction and buffered nonsparseness correction. The new techniques consider the effects of crater obliteration and subsequent recratering while measuring CSFDs in areas of high crater density. Currently, the ArcGIS add-in CraterTools can be used to apply the well-established techniques. The tool relies on Esri's ArcGIS environment and is restricted to 32 bit and single-core computing. These limitations make the implementation of the new geometric corrections in CraterTools inefficient, as the new techniques are computationally more intensive than the well-established ones. To this end, we developed CSFD Tools, an application to conduct CSFD measurements from shapefiles. It supports 64 bit and multicore data processing and uses existing open geospatial libraries. Open libraries, however, conduct spatial measurements on a Cartesian plane and do not take a curved planetary surface into account. Therefore, we implemented methods for geodesic measurements and workarounds for the geodesic modification of polygon data to minimize map distortion effects during CSFD measurements. As a result, the new nonsparseness correction and buffered nonsparseness correction techniques can be applied through a software tool.
Plain Language Summary Planetary surfaces can be analyzed by their impact crater record. For example, many craters in an area represent an old surface and few craters in an area represent a young surface. When a surface is very old and has many craters, the total number of craters we see on satellite images may be different from the total number of craters, which formed over time. This is because new craters erase old craters when they impact. There are two new techniques to count craters on a planetary surface, which consider this effect. They are called nonsparseness correction (NSC) and buffered nonsparseness correction (BNSC). A computer program called CraterTools can be used to count craters. It uses software that is slow by today's standards. The new NSC and BNSC techniques cannot be added to CraterTools because they require calculations that are more complex. We developed a new computer program, which uses open and faster software libraries. However, these libraries do not take the effect of a curved planetary surface into account. This would lead to errors during crater counting. Therefore, we developed methods to consider this effect. This is done to make the new NSC and BNSC techniques available for other researchers.
- 出版日期2018-6
