Usage for the VPE Laboratory

GRASS comes with tools used to import 'raw' raster scan pictures, DEMs, and categorical data. These tools allow for the building of new databases. GRASS can then be used to create a planetary database, such as of Mars and Earth.

In Section 1.3: Tutorial, you will be shown the steps needed to obtain data on Mars from a CD-ROM, and, using this data, create a GRASS database. You will also be shown the process of registration using data from Mt. Kilauea, a volcano in Hawaii (also from a CD-ROM.)

Registration is the process of combining spatial information that corresponds to each other on different datasets.:

In many image processing applications it is necessary to form a pixel-by-pixel comparison of two images of the same object field obtained from different sensors, or of two images of an object field taken from the same sensor at different times. To form this comparison it is necessary spatially to register the images and thereby correct for relative translational shifts magnification differences and rotational shifts, as well as geometrical and intensity distortions of each image ( W. Pratt, Digital Image Processing, 1978 )
Registration is a key advantage of using GRASS.

GRASS is ideal for the displaying and processing (e.g. sizing) of raster images (Figure 1: kildem.1.gif).

It also allows for the overlaying of images into one congruent orientation (Figure 2: img.pts.4.sml.gif):

Using an elevation map of the site (such as DEM data - Figure 3: SG3d.1.gif), one can create a 3d map representation that corresponds to the raster image.


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Email to:
Kurt Schwehr schwehr@cs.stanford.edu -- Dan Delgado renata@eos.arc.nasa.gov

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