Occassional thoughts about orienteering

Monday, November 28, 2011

Aspleaf's dream...nightmare?


Back in the day, Aspleaf predicted the future of orienteering as an olympic sport.

 The race shown in the video isn't quite what Aspleaf predicted, but it isn't that far off....and it looks pretty cool.


I came across the video at Semidesiert-O.  It is worth a look for the unusual orienteering maps.

Back to okansas.blogspot.com.

posted by Michael | 8:02 PM


Sunday, November 27, 2011

Karst terrain contours


Here's some very nice terrain that needs to be mapped.

This is a small section of the terrain at Rock Bridge State Park near Columbia, Missouri. The map clip shows a small bit of terrain (about 750 meters wide).

The entire park is large, but the karst terrain covers just about 1 square kilometer (and only about half of the area is forested).

Back to okansas.blogspot.com.

posted by Michael | 5:14 PM


Friday, November 25, 2011

More tests with laser scan/lidar data for mapping


I've been experimenting with laser scan data and the latest version of OL-Laser. I've been learning more and more about how to use the data and what sort of information I can get.

Here's an image that combines the laser scan contours and cliffs generated by the OL-Laser software. You can tweak the contours and cliff settings, but the image is just to give you an idea of the basic information that is easy to pull out of the data with OL Laser.

The next image shows the results of some quick field checking. You can see some adjustments to the contours (and, in fact, the contours in the field checked image were derived from the same data but created with QuickGrid rather than OL Laser).

When you compare the two images, you can see that OL Laser did a good job of finding the cliff and cliff-like features. It doesn't distinguish between rock faces and earth banks (though you can pretty much assume that the steep edges along stream banks will be earth rather than rock in this sort of terrain). Given the settings I used, the software also highlighted areas that are steep and rocky but broken up enough that they aren't really cliffs. I tend to map those areas using either the boulder field or rocky ground symbol.

The snapshot shows the lone cliff that is a bit east of the pair of boulders.

The below snapshot shows some of the area that OL Laser picked out as a cliff but that I've mapped with the boulder field symbol

Back to okansas.blogspot.com.

posted by Michael | 3:53 PM


Monday, November 21, 2011

Comparing the map and the lidar data


Here's a comparison of the current orienteering map and some laser scan (aka lidar) data of the same area. First, take a look at the current orienteering map with 5 meter contours.
I'm not sure of the source of the contours. I think it might be USGS "DEM" (I think DEM = digital elevation model). Now, take a look at the laser scan contours. The countours are drawn at 2.5 meters (with a little bit of smoothing). I think you'll notice that these contours are a bit more detailed.

Finally, take a look at the laser scan "slope" image. In the slope image, the steeper the slope, the darker the shade. The slope image is especially useful for picking out the earth banks along streams and erosion features. In this area, you can also see some of the older trails (look for the trail that runs parallel and just to the east of the road on the top of the hill).

I used OL Laser to generate the contours and the slope image. I'm a fan of OL Laser. I find it fairly easy to use and I'm able to get a lot of information out of the laser scan data without a lot of work.
Back to okansas.blogspot.com.

posted by Michael | 7:17 PM


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