ANALYSIS OF MARS DATA USING ARCOBJECTS AND MODELBUILDER
P. Saiger1, M. Tiede2, F. Preusker1, M. Waehlisch1, H. Asche3, J. Oberst1, R. Jaumann1
1 - German Aerospace Center
2 - University of Applied Sciences, Neubrandenburg
3 - University of Potsdam, Institute of Geography
peter.saiger@dlr.de
Geographic Information Systems
(GIS) are powerful tools for integration of different planetary datasets, e.g.
images, spectral data, and digital terrain models which are typically given in
different formats like vector and raster. We are currently involved in a
project to import large volumes of data from the recent Mars missions into a
planetary GIS database.
Before working in GIS with
such datasets, it is necessary to prepare them for import. Using ArcOBJECTS, a
collection of ArcGIS programming objects, and object oriented programming
languages like Visual Basic .NET, we create ESRI shape files according to a
suitable specification. Regular shape files are not sufficient, because data
points have often large numbers of attributes associated with them in the
original ASCII dataset. Here, the MOLA (Mars Orbiting Laser Altimeter) dataset
is a typical example with over 33 attributes per Laser shot. These have to be
imported using a .dbf database file. Once this is accomplished, it is possible
to combine all these different datasets with raster information, such as HRSC
(High Resolution Stereo Camera), or MOC (Mars Orbiter Camera) images, or MDIM
2.1 maps for joint analysis.
Subsequently, we have
developed an improved method for analysis of volumes for topographic
depressions or positive relief features of large extent. ArcGIS Desktop
provides a measurement tool with the “Area and Volume Statistics“ module. However, this module is very limited
in scope. It is possible to “calculate statistics above plane“ or “calculate
statistics below plane“ for volume. This is not accurate enough for measuring,
e.g. craters or valleys covering large areas, because the reference surface may
not be planar. Furthermore it is not possible to specify a selected area. The software can
handle only the entire data set. In our improved measurement tool, we consider the resolution of
the underlying digital terrain model, the topographic trend of very large areas
and the software allows
us to interactively choose defined sub-areas for accurate surface feature
analysis of differential levels.
We also implemented ArcOBJECTS
to define our appropriate solutions for better handling large datasets and also began studying
the widespread Martian drainage networks using ESRI`s “ModelBuilder” to
automate the time-consuming step by step workflow. The goal is to find pour
points to calculate the watersheds, for runoff water only.
We have applied our GIS tools
for various geologic mapping and interpretation tasks, and for 2d and 3d
visualisations and analysis. We will demonstrate several examples to import,
measure and project large datasets in different formats with ESRI’s object
model for ArcGIS 9.X.