Developing Cross Sections through Random Longitudinal Lines
| A HYPACK user contacted us last week. His company
had run longitudinal lines along a river in order to develop a centerline for navigational
purposes. They collected the data in HYPACK, processed it and then exported the results to
a DXF file. They then developed their centerline in AutoCAD. The figure to the right shows
their CAD file, displayed in HYPACK MAX. I thought of first using the new DXF2LNW utility, which allows you to convert polylines to LNW format. The problem in this case was that they had arcs around the turns and the DXF2LNW program doesn’t understand about curved lines (not yet, anyway). So, I decided to brute force it. |
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| I zoomed in on the area and picked off a list of X-Y coordinates for
the planned line. I picked four or five points around each turn, depending the the size of
the arc. The figure to the right shows one of the zoomed curves. You can also get a better look at their centerline and the random sounding lines they ran.
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| I then entered the X-Y coordinates in the Line Editor of HYPACK MAX. I then told it to generate a cross-section line 50 meters to either side with 100 meters spacing between the lines. The lines were generated and then saved. The resulting cross section lines are shown in the figure to the right. The client next wanted them to cut cross sections through each line. The problem with this is that their data is too sparse. Each cross section would only have a point or two (some had none!). In order to solve this problem, we have to "densify" their data set. I created a Matrix file about their data points with cells 10m x 10m. |
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| I then took their data file (they provided a separate XYZ file) into
the TIN MODEL and created a surface model. I then used the Export feature of the TIN MODEL
to fill the matrix. The resulting "dense" data set is shown in the figure to the
right. We now have plenty of data to cut sections. [If you decide to do this, be prepared to spend some of your life behind bars.] I then reloaded the new "dense" MTX file into the TIN MODEL along with the LNW file I made above. I then told the program to Export – All Format files. This allows you to "cut" sections through the TIN MODEL. |
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| I then loaded the resulting files into the VOLUMES & SECTIONS program. Voila! |  |
