Ever had problems making lines readable across different background colors? Here's an interesting technique (click on the image to see the whole picture):
The image above shows a property boundary; the one below shows a social trail network.
We've "extruded" a circular cross-section along each trail path to create a thin "tube." This tube is a 3d object that is subject to the lighting model and can be assigned a variety of reflective characteristics. It has the additional advantage of diminishing in size with distance, so it provides depth cueing into the scene. We started using this some years back to overcome difficulties with drawing simple 2d lines over varying background colors.
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