The Geospatial Desktop is Now Available
The Geospatial Desktop book is now available for order from Amazon
For information on what’s in the book, see About the Book and the Annotated Chapter List.
Take a look at the Changes page to see what’s new/different in this revision.
January 23, 2012
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Posted in: Book
The Proof is in Hand
The proof copy of The Geospatial Desktop has arrived and is being reviewed. It shouldn’t be long now before the book is available on Amazon.
If you want to be notified when the book is available, use the Contact form to provide your email address. We’ll notify you when we have a firm date for the release of the book.
You may also want to sign up for the Locate Press newsletter.
January 18, 2012
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Posted in: Book, GDAL, GMT, OGR, QGIS
Converting E00 Files
Although some GIS applications support using E00 files directly you will likely find it more efficient to convert them to another format. This can be easily done with ogr2ogr.
November 24, 2011
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Tags: ogr2ogr, posgresql, postgis, spatilite · Posted in: OGR
Revised Version
Desktop GIS published by Pragmatic Press is currently out of print.
We are working on a new, revised version of the book titled The Geospatial Desktop to be published by Locate Press around the first of the year.
If you want to be notified when the book is available, use the Contact form to provide your email address. We’ll notify you when we have a firm date for the release of the book.
For more information, feel free to contact us.
November 21, 2011
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Tags: book · Posted in: Book
The Volcano and the Buffer
Here in Alaska we have over 130 volcanoes with more than 50 being active in about the last 250 years. Presently Mt. Redoubt is in an eruptive phase and has been since March 22. Ash from the volcano has fallen in a number of communities and areas throughout the state. A couple of weeks or so ago the reports from the Alaska Volcano Observatory indicated the ash was falling within 30 miles of the volcano. I decided to do a quick analysis to see what areas might be affected.
This is an example of simple analysis with GIS. We just get the location of the volcano and create a 30 mile buffer and then visually determine the affected areas. To do this we need data for towns and the location of the volcano. We could use a volcano layer if we had one, but in this case I’m going to use a simple method to create a point shapefile from text data.
April 27, 2009
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Tags: gdal, qgis, vrt · Posted in: GDAL, QGIS
Creating a Standalone GIS Application
In this example we are going to begin to build a standalone GIS application using Python and the QGIS libraries. We’ll start simple by creating an application to load and display a shapefile. In later posts we’ll enhance the application to provide some map tools and other features.
February 7, 2009
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Tags: pyqgis, python, qgis · Posted in: Apps, QGIS
Creating an Overlay Map with GMT
In our previous GMT examples we used a single command to create a simple globe and create an annotated map. In this example we will create a base map and then use the overlay feature of GMT to plot the location of volcanoes throughout the world.
The first step is to create the base map using pscoast:
pscoast -JN0/26 -R-180/180/-90/90 -W -G220/220/220 -S0/192/255 \
-N1 -B60g10 :."World Volcanoes": --PAPER_MEDIA=archA -K > world_volcanoes.eps
January 16, 2009
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Tags: gmt · Posted in: GMT
Developing Custom Applications
Sometimes the “out-of-the-box” GIS applications don’t fulfill your need. While writing your own application isn’t something to enter into lightly, sometimes it is the best solution.
A custom application might be the answer when you need:
- A simplified interface
- Special functions and tools
- Integration with other tools and data
The key to a successful custom application is to leverage the available toolkits and libraries—in other words let someone else do the hard work for you.
Some open source resources for writing your own applications are:
In a subsequent post we’ll take a look at writing a simple application to display some data using Python and the QGIS Python bindings.
December 5, 2008
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Tags: applications, mapnik, python, qgis, udig · Posted in: Apps
Extracting Features from a Vector Layer
Suppose you want to extract features from a vector layer to create a smaller subset. This can be very handy if you have a large dataset and need just a portion of it for your current project. If your data happens to be in one of the formats supported by OGR, you can use ogr2ogr to create a new layer.
March 28, 2008
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Tags: clip, ogr2ogr · Posted in: OGR
Creating an Annotated Map with GMT
For this example, we’ll create a map of Alaska and annotate it. If you looked at the Simple Globe example you’ll recall that the -R switch controls the extent of a GMT map. Alaska ranges from about 172 degrees east longitude to 130 degrees west. Using 360 degrees for the entire globe, this translates to a region extending from 172 degrees to 230 degrees. For the Alaska map we will use the Albers Equal Area Conic projection. Looking at the syntax for pscoast reveals that this requires the use of the -Jb switch. In this case, we use the lowercase “b” to indicate that we will specify the size of the map using a scale. First lets look at the command used to create the map:
pscoast -Jb-154/50/55/65/1:12000000 -R172/230/51/72 -B10g5/5g5 -W1p/0/0/0 \
-I1/2p/0/192/255 -I2/2p/0/192/255 -I3/1p/0/192/255 -I4/1p/0/192/255 \
-G220/220/220 -S0/192/255 -L210/54/54/1000 -P -N1/1p/0/0/0 -Dl >gmt_alaska_coast.eps
This looks like quite a complex command, but it’s really not too bad once you get past all the numbers and slashes.
February 22, 2008
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Tags: gmt · Posted in: GMT
