Occassional thoughts about orienteering

Friday, October 29, 2010

Video games and map reading


Research on using video games to improve map reading:

You can read more about it on Brian Verdine's web page.

Back to okansas.blogspot.com.

posted by Michael | 8:51 PM


Thursday, October 28, 2010

Something to learn from cyclocross?


My friend Leslie linked this cyclocross video:

Cross Crusade Race #4 PIR from Burk Webb on Vimeo.

As I was watching it, I thought, "we ought to do videos like this for orienteering." An orienteering could easily include some interesting images and rough conditions.

Cyclocross and orienteering have some of the same appeal. Both are tough sports that attract fairly small crowds. There is definitely some overlap among competitors. That's local orienteering legend Mean Gene racing cyclocross below.

The two sports have some big differences. Cyclocross is an equipment sport. Orienteering isn't. Cyclocross is easy to explain and most people will understand it ("it is an off road bike race"). Orienteering isn't like that. Cyclocross is a good name. Orienteering is not.

Back to okansas.blogspot.com.

posted by Michael | 7:57 PM


Sunday, October 24, 2010

Today's fieldchecking with a lidar image


Below is a laser scan (lidar) image of a section of forest that I was fieldchecking today. I created the image with OL-laser.

I highlighted a few features:

1. These blobs in the forest are individual cedar trees. They are quite useful to have on the base map.

2. The east-west running linear feature is an old rock wall. Most of the wall is no more than 0.5 meter high. It will be drawn as a ruined rock wall on the final map.

3. The diagonal line looks a bit like the rock wall. But it isn't a rock wall. It turns out it is a fallen tree.

4. The north-south running linear feature (which is a bit hard to see) is another old rock wall, mostly ruined.

The stream bed that runs east-west across the middle of the map stands out clearly.

The image below is a Google earth photo. You can see the east-west running rock wall pretty clearly. Some of the cedar trees are visible, but not as easy to spot as on the laser scan image.

Back to okansas.blogspot.com.

posted by Michael | 4:11 PM


More map comparison


Aspleaf posted maps from 1966 and 2010.

The course is from the 2010 district night champs.

Back to okansas.blogspot.com.

posted by Michael | 9:51 AM


Saturday, October 23, 2010

Comparing mapping styles


Comparing two maps of the same terrain, posted by Jagge at Attackpoing:

You can argue and discuss whether this sort of development is good or bad. I'm not really sure. It seems consistent with the development of orienteering maps over the years - a move toward more and more contour and runnability detail.

I don't really know how much further it can go. With laser scan (lidar) data for basemaps, it is easy to fieldcheck a map with a 1 meter contour interval for a final map that will have a 5 meter interval. That will make it a lot easier - and more tempting as a mapper - to add form lines. As mappers become better at extracting vegetation data from laser scans, fieldcheckers will have an easier time mapping runnability detail, too. Drafting on a computer as opposed to the old-style pen-and-ink also makes it easier to add more detail.

Jagge had some interesting comments on the map comparison.

I think the newer-style maps change orienteering technique a bit. An obvious change, which Jagge notes, is that they make it harder to see the map. It is hard enough that young runners, with young eyes, often carry magnifiers. The maps also provide a lot more information that could help with the "micro" route choices - i.e. the decisions about how to best move through the forest. On the older-style maps, you made your way through the forest by looking ahead and having some general familiarity with the type of forest. As you ran, you picked your way through the terrain. On the newer-style maps you can get more runnability detail from the map itself.

Here's a similar comparison of maps that I made a few years ago.

Back to okansas.blogspot.com.

posted by Michael | 10:41 AM


Sunday, October 10, 2010

Enough to get started with Lidar?


OL Laser is a program for creating orienteering basemaps from lidar (aka laser scan) data. I'm far from an expert on either lidar or OL Laser, but I've been playing around with the program and thought I'd write up some notes.

I'm impressed with OL Laser and have found it easy to use. I'm sure I've just scratched the surface of what it can be used for. I'm far from being an experienced user.

OL laser is useful...but it is written in Swedish. I thought I'd translate bits of the main screen. With the translation and a willingness to experiment (and a bit of lidar data), I think you'll be able to get started even if you don't understand Swedish.

You can download OL Laser (click on the "ladda ner" link)

Below is the main screen and translations of some of the items on that screen.

The first three buttons are for opening the data:

Oppna laserdatafil = open the laser data file
Spara laserdatafil = save the laser data file
Filinfo = file information

The next two buttons are for creating the "GRID or TIN" (a Google search for "lidar and GRID" and "lidar and TIN" should explain the terms):

Skapa GRID/TIN = create the GRID/TIN
Installningar = settings

Next are two blocks of buttons. One is for contours (hojdkurvor) and the other is for images (bilder). I'm going to focus on the image items first:

The drop down menu labelled "valj typ av bild" means "select the type of image." There are four options:

Laserpunkklass = laser point category
Intensitet = intensity
Lutning = slope
Terrangskuggning = terrain shading

You'll see three buttons below the drop down menu:

Installningar = settings
Skapa bild = create image
Spara bild = save image

I'm just going to skip over the "hojdkurvor" (i.e. contours) menu and go to the final set of buttons labeled "rita" (i.e. draw). You'll see two boxes you can check:

Rita ut kurvor = draw contours
Rita ut bild = draw image
Installningar = settings

That's just barely enough translation that you ought to be able to begin to play around with the program.

I'll walk through an example:

The first thing you need is some data. If you've got some data, great. If not, you can find some online. One source is the Kansas Data Access and Support Center's collection of lidar. The data are free to download, though you have to register. The most interesting data are the "all returns" files.

Once you've got some data, you can open it in OL Laser (use the button at the top of the program screen labeled "oppna laserdatafil"

Next, you'll move to the GRID/TIN section of the menu. First, click on the "installningar" (i.e. settings). A new menu opens. Now you've got lots of options and lots of info. It is useful to understand Swedish at this point. I'm not going to translate all the terms. Instead, I'll describe the easiest thing to do to start playing with the data.

Look for the checkboxes under "klassificering" (i.e. classification). Make sure the box labeled "mark" (i.e. ground) is checked.

Look for the button/boxes just below under "returnummer" (i.e. return number). Make sure "sistareturnen (mark)" is checked.

At this point, you've opened the data file and told the program that you're going to create a GRID of the ground.

Go back to the main menu and click on "skapa GRID/TIN." It should take a few seconds to create the GRID.

At this point, you don't have anything to look at.

Go to the "bild" (i.e. image) set of items and select the type of image from the drop down menu. "Terrangskuggning" is a good first choice. Don't worry about the "installningar" just click on "skapa bild." It takes a few seconds to create the image.

At this point, you still don't have anything to look at.

Go to the "Rita" section of the main menu and click in the box labeled "rita ut bild" (i.e. draw the image) and you should get an image.

That's a quick - and rough - intro to OL Laser. You can start to play round with different images and different settings.

I've written about my various experiments with lidar. I'm very much self-taught. I'm far from being an expert. I don't really understand all of the technical details of how lidar works or of how best to use the data. But, I've learned enough that I can use the data to generate a useful basemap.

Back to okansas.blogspot.com.

posted by Michael | 4:18 PM


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