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Category Archives: tracklog

As a follow-up to recent and elementary post about how useful Google Earth is for field mapping, check out the traverse that I actually made:

Also, check out the online photo album that I created from the geotagged images shown on the snippet above:

Lower Walker River

If you don’t think these technologies are useful, you may need to seek counseling.

Geotagging photos of key outcrops or geoscapes in the field is a very useful thing to do. To geotag a photo is to inscribe the digital file with geographic coordinates. Lots of people are doing it, but I fear that not enough geologists are.

All photo files from digital cameras have an exif header. This stands for ‘exchangeable image file format’ and it is the area where the file name, date, time, exposure, etc., info is stored. Recent interest in digital mapping has lead to the ability to add specific geographic information (i.e. geographic coordinates) to the exif header. This offers great potential to the field geologist. There are various ways to geo-tag a photograph. Up to now, my preferred way has been to use the free photo-sorting program Picasa (yup, a Google product…more on this at related post) wherein you can manually link a photo to a specific location by dragging it to the map. This works fine in many situations, but can be tedious. Over the last couple of days, I have experimented with a more automatic approach using a program called ‘Geosetter‘ which very efficiently and easily geotags my field photos by directly linking their time-stamp with a corresponding GPS tracklog. Brilliant! In this way, you automatically create a geographically accurate set of field photographs. If you use Google Maps, Picasa, or Google Earth, you can then display the images on a base map of your choice.

Check out an example I made using a Picasa Web Album:

Once at the album, click the ‘view map’ link. Be sure to zoom way in using the satellite mode to fully appreciate how useful this application is. Furthermore, consider the fact that some of your field photos may be of great value to other geologists, botanists, historians, etc., at some point in time. By tagging them with key words, geo-tagging them, and making them available online, you may be doing a great service to other scientists. Burying them in a paper archive or on a CD somewhere does no good.

Note, you can use Picasa to geotag your photos one-by-one through a link with Google Earth, using a simple drag-and-drop procedure. At some point it is obvious that digital cameras will automatically stamp the file with the coords, but I think the linkage between digital photos and a GPS tracklog may be the best way to go.

In order to learn more about tracklogs on your GPS, simply break down and read the short manual that came with the unit. If your unit is more that 3 years old or uses more than 2 AA batteries, you should upgrade. One important consideration is upgrading to a unit that has a memory card slot. In that case, you will be able to store considerably more data. In the case of my Garmin GPS 60csx, interacting with the memory card is actually easier than interacting with the unit. Also, it automatically creates individual logs on a per day basis. Very handy.

Please, please (!) rid yourself of the belief that you need to turn the unit off all of the time to save batteries. Newer units can run for 2-4 days on a single set of batteries when turned on and off at the beginning and end of the field day. If you are worried about wasting batteries, then use rechargeable ones and move on, man. In order to maximize the value of the track log, the unit should remain on during the entire day (except during lunch, when you change batteries, or when you are mapping underground).

A colleague at NBMG recently turned me on to a very handy program from the Minnesota Department of Natural Resources that easily converts GPS tracklogs and waypoints to shapefiles to use in GIS software. The program is called DNR Garmin and is extremely handy. Kudos to the author. The program can suck data right off the unit or can read from a gpx file. The image above is proof that it works.

I have spent the last 7 days doing field mapping in southern Nevada and fine-tuning some new and simple digital methods. Namely, using the GPS tracklog capability to document my progress, augment my note-taking, and the really cool application of automatic geotagging of field photos (look for related post about that).

GPS tracklogs: Why?

As a field geologist I am enamored with a tool that automatically knows my position in my map area. The handheld GPS is the most useful tool for geologists that has come around in a long time. If you don’t use one and prefer to eyeball or triangulate your position the old fashion way, then grab your slide-rule, get on your horse and have at it.

Most of us already know that GPS is great to establish specific waypoints of key observations and sample locations, for example. A GPS tracklog is one step better in that it represents an accurate and complete record of an entire traverse over the course of a day, days, or weeks. Not only is this a useful method of documenting/demonstrating your progress in the field, but it also serves as an important complement to note taking. Once you have traversed a section of your field area, the tracklog will serve as a key reminder of your exact path. In your notes, if you often refer to what was crossed since the last formally recorded waypoint (i.e. SLO, or ‘since last observation’), the track-log provides an accurate cartographic representation of exactly where you were since the previous observation (including backtracking to retrieve your forgotten rock hammer). Also, since the track-log can be tuned to record at very short intervals, you can even resort to recording the time of day to link field observations to your track log. Maybe that is too informal, but consider the point that this may be a way to make a quick observation at a time when you don’t want to halt the traverse and formally record your position, etc., seeing that you are actually recording it anyway by recording the track log. Another short-hand approach relates to field photographs as described in a subsequent post.