quick-start tutorial


Site Administrator
Jul 31, 2004
Ben's Branch, Stephen Creek
There are a lot of new features on the LIDAR site, but here's a quick exercise that should help you understand the map controls. We'll be looking at this gravel pit next to Oswego Lake that appears pretty unimpressive on a topo map


But it offers a good opportunity to observe the effects of lighting on the terrain. We'll use the plain-white solid terrain option, which is especially good at showing details. Get started by going to the following link. This may take a little while to open, so just wait for it to appear after you click.


Observe what happens when you move the "sun" from East to West. Just drag the slider from left to right and notice what happens to the highlights and shadows. You can also play with the other sun controls and observe the effect. Setting the East/West/North/South sliders to the ends of their ranges helps bring out terrain features. Setting the height slider low also accents the terrain. You may need to adjust the brightness to compensate. If you really mess things up, just click the Reset Sun button to restore the default lighting.


Next, let's have a look at the underlying elevation data. Zoom in to about 200% and observe the elevation values as you slowly drag the map around.


Notice how the elevation increases when you position the crosshairs over one of the piles of gravel. Each individual map contains 4,194,304 distinct elevation samples that are spaced one-meter (3'-3") apart. This is why it takes so long to load the maps!


Now switch to 3d mode and use the mouse to manipulate the map.


The left button moves your position, the scroll wheel moves you in and out, and the right button rotates and tilts your view. Notice that the crosshairs are always at the center of rotation. Play around with different map views, and notice how the compass keeps you oriented to where North is.


Next, we'll have a look at vertical exaggeration.


The default value is 2.5x. Change it to 4.0x and the gravel pit becomes a canyon!


Or set vertical exaggeration to None and you will have a correctly-proportioned view. You'll probably want to tweak the lighting controls when you change vertical exaggeration, to bring out the maximum amount of detail. Your vertical exaggeration setting will stay in effect for all maps until you leave the site.


This is just a quick start - now it's up to you! Try the different overlays - aerials and shaded terrain - and experiment with different lighting to bring out the details that interest you. Enjoy!
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