Wednesday, February 23, 2011

Geologic Cross Sections and Adobe Illustrator

Last academic quarter, I spent time trying to understand how to easily remove vertical exaggeration (VE) from tabulated elevation and distance data in Adobe Illustrator.

Adobe Illustrator has a chart tool.  It isn't very robust or powerful.  In fact, it can be a pain to work with.

However, there is a way to manipulate its initial size such that (hopefully) VE = 0.

Perhaps you have found a better way? Here's my final solution.
  1. Import the data into a temporary scatter plot and take note of its automatic maximum vertical and horizontal tick values.  These values seem to be consistent no matter how you size the chart area.  Delete it.
  2. Take those maximum values and convert to the scale that you need to use (e.g., 1:24000) 
  3. The final two numbers should be in units of your artboard
  4. Create a new scatter plot chart but taking care to snap its size to your determined horizontal and vertical map distances using snap guides
  5. You should have VE at or near zero; verify this!
  6. Configure your chart: remove point markers, set line weights (tricky...), etc.
  7. Select your chart and ungroup it.  Yes, you do want to destroy the ability to change graph data because you'll really want to modify your new profile graph!
  8. See "Coloring Cross Sections: Adobe Illustrator Paint Groups" for what to do next.
This method hinges on the assumption that the drag box is exactly where your data will show up, with the axes coinciding or just barely exterior to it.  It may not be the best assumption but it seems to be the case.  Be sure that all the ticks are equidistant and there are no distortions on the axes.

In an ideal world, we would scale elevations and horizontal distances to artboard distances.  Then, import and plot the points so they automatically coincide with the units of the artboard WITHOUT using the chart tool.  This would remove the guesswork... is it possible?


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