Harvard University
Using and plotting orientation data with gOcad
Introduction
Orientations of planar elements such as fractures, bedding, faults or any
foliations are a basic data type in recording the geology of an area. They
represent next to the geologic map often the most critical input for reconstructing
the geometry of a structure in cross-sections or 3d models. In order to
facilitate the use and analysis of such orientation data, two add-on wizards
for the modelling software gOcad have been implemented - Digi and StereoPlot.
Digi helps in digitizing strike and dip information available on structural
maps or as raw data. StereoPlot collects orientations and produces a contoured
density plot on a sphere besides a traditional equal area stereographic
projection. Using these tools it becomes straightforward to bring these
data into a 3d model and to analyse them in their original spatial context.
Screenshots
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for full image, 25kb)
Example of digitized fault and bedding orientations.
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for full image, 81kb)
Plot of poles to bedding in a equal area stereographic projection (Schmidt)
produced by SpherePlot.
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for full image, 130kb)
Appropriate for a 3d modelling environment, a density plot of poles
to bedding is best represented on a sphere.
An surface which corresponds to the most frequent orientation has been
added. Output of SpherePlot.
(click
for full image, 13kb)
With Digi - the wizard for digitizing orientation data - it is easy
to quickly enter strike and dip of a large number of data points.
(click
for full image, 18kb)
SpherePlot allows plotting and contouring of poles on a sphere and
a stereographic projection.
(click
for full image, 27kb)
The help screen.
Download
I prepared an archive which includes the wizards and example data. Digi
probably runs only on gocad 1.5.X. StereoPlot is tested on both, 1.5.X
and 2.0.1.
Download (free for academic use),
Comments
If you like this package and use it for your work, please contact
the author.
Enjoy,
A. Plesch
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