dylan's blog

Detailed Magnetic Declination

Submitted by dylan on Fri, 2008-03-14 20:45.


Setting the magnetic declination on a compass is a critical step in accurate measurement of bearings that can be translated to map or survey. As the location of the magnetic north pole is constantly moving, the magnetic declination reported on older topographic maps or compass housings are probably out of date. Current declination values for a single point, or for large regions can be found on the NOAA sites:

These resources are helpful, but a current, detailed (state-level) map of magnetic declination would be interesting.

A need for data management courses in higher education

Submitted by dylan on Thu, 2008-01-17 00:00.

Working with large piles of complex data can be a difficult task, even for seasoned experts. What happens when a non-specialist is tasked with collecting, managing, and ultimately warehousing large amounts of painstakingly collected data? What happens when multiple non-specialists are concurrently working on these data? How can a revision history be maintained when a small set of files are being passed around via email, or appended to a "master" document?

( categories: )

Mapping Wi-Fi Network Range with GRASS, Kismet, and python

Submitted by dylan on Sun, 2007-08-12 20:56.

Update to a previous post on mapping wireless network information with GRASS, kismet, and a custom python script. This time, some modifications to the python XML-processing script so that we can work directly with the Kistmet-xxx.gps files. Processing the .gps files allows one to produce a shapefile from each trip to the field. The shapefiles can be combined in a GIS (like GRASS) with simple vector processing (i.e. patching). Example steps are presented below, complete with an RST-based interpolation of wifi card signal and noise observations.

( categories: )

Vacation + Sailboat + GPS + GRASS + R

Submitted by dylan on Fri, 2007-08-03 20:41.

I recently spent some time near Huntington Lake- one of the more interesting sailing lakes in California. Lashing a GPS to the front of the boat was an enlightening way to look at the spatial and angular trends in the amount of speed I could get out of this boat. With 218 sq. feet of sail, and only 320 lbs of displacement (i.e. the boat's weight) - the Hobie 16 is an exciting 2 person boat for light to medium winds. With my regular crew absent we did not use a trapeze and thus were only able to get the boat to about 11 knots (6 m/s).

( categories: )

Target Practice and Spatial Point Process Models

Submitted by dylan on Mon, 2007-06-11 06:40.


( categories: )

Exporting GRASS Raster Data to ArcGIS

Submitted by dylan on Sat, 2006-11-04 03:54.


Images from Pinnacles Soil Profile Analysis

Submitted by dylan on Wed, 2006-11-01 16:14.

Misc. scanned images from work at the Pinnacles National Monument, in collaboration with the NRCS and NPS.

Mapping Wifi Networks with Kismet, GDAL, and GRASS

Submitted by dylan on Thu, 2006-09-07 00:30.

Some simple examples of how to extend data collected from kismet along with gpsd.