Open Source GIS and Mapping Ideas

Batch Projection and Masking with GRASS

Submitted by dylan on Wed, 2008-05-07 18:21.

 
Premise

PRISM Monthly Precip - CA

Submitted by dylan on Wed, 2008-05-07 18:21.
PRISM Monthly Precip - CA

PRISM Monthly Precip - USA

Submitted by dylan on Wed, 2008-05-07 18:20.
PRISM Monthly Precip - USA

Simple Python Interface to USGS TNM Elevation Service

Submitted by dylan on Tue, 2008-04-29 06:31.

 
Premise
Wanted a simpler way to access the USGS seamless elevation look-up service. Python seemed like a logical start. Note that the response from the USGS webservice is not correctly identified as valid XML by the python XML-parser. Therefore there is a small amount of scrubbing used to coerce the response into valid XML. Comments on why this is, or is not, a good idea are welcome.

 
Update It looks like the USGS service does not accept POST-style requests. I have made some small changes to the script below.

Detailed Magnetic Declination

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

 
Premise:

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pole is constantly moving, the magnetic declination reported on older topographic maps or compass housings are probably out of date.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.

Generic GRASS-GMT Plotting System

Submitted by dylan on Sat, 2008-03-08 00:34.

 
Premise:
A generic press-quality plotting system for GRASS, based on GMT. Still a ways to go.

Testing for linearity

Submitted by dylan on Fri, 2008-02-01 20:04.
Testing for linearity

Two visualizations of the deviance between coordinates positions, at the control point locations.

Higher Order Transformations

Submitted by dylan on Fri, 2008-02-01 19:57.

 
... Continuing from the initial example session in R ...

Comparision with output from v.transform

Submitted by dylan on Fri, 2008-02-01 19:23.

 
First the output from R:
Looking at the residuals from the regression model used to map bad coordinates (x,y) to good coordinates (nx,ny):