Calculating Isopach Thickness

(Note: In all scripts and command lines that follow, a backslash ( \ ) at the end of a line indicates that the current line is continued on the line that follows. When creating the script or typing the command line, these lines should be entered as one continuous line without the backslash.)

Sometimes it is desirable to add a true isopach thickness (thickness in the direction normal to bedding) to an existing 2D grid. When a value is added to a grid in the Formula Processor, the thickness added is an isochore thickness (vertical thickness). The following script takes a 2D grid and, using the Formula Processor, adds a specified isopach thickness (i.e., in the normal direction) to calculate another surface:

#!/bin/sh -ue

if [ $# -lt 3 ]
then
echo "Usage: $0 input.2grd thickness \
output.dat"
exit 1
fi

dat=temp$$.dat
echo "Exporting grid $1 as scattered \
data file..."
ev_export -o $dat $1

echo "Adjusting exported nodes \
by thickness $2..."

ev_fpfp << EOF
fx = -partialx ($1);
fy = -partialy ($1);
factor = $2 / sqrt (fx*fx \
+ fy * fy + 1);
$dat<factor> = bakint (factor, $dat<x>, \
$dat<y>);
$3<x> = $dat<x> + $dat<factor> \
* bakint (fx, $dat<x>, $dat<y>);
$3<y> = $dat<y> + $dat<factor> \
* bakint (fy, $dat<x>, $dat<y>);
$3<z> = $dat<z> + $dat<factor>;
EOF

rm $dat

% chmod +x isopach.sh

% isopach.sh input.2grd thickness \
output.dat

The results of this script is a scattered data file (in this case output.dat) that has a value at every grid node location. This file can then be gridded (using Modeling -> 2D Minimum Tension Gridding).

 
[Home] [Corporate] [Events & News]
[EarthVision] [Support] [Services] [Contact Us]

Last updated: March 22, 2007