Author Archives: leigh

Python Disabled in QGIS?

By | December 20, 2011

This afternoon, I opened QGIS, and was greeted with a strange error message: Couldn’t load PyQGIS. Python support will be disabled. Traceback (most recent call last): File “”, line 1, in RuntimeError: the PyQt4.QtCore module is version 1 but the qgis.core module requires version -1 QGIS will still open if Python support is disabled, but […]

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Getting to Know QGIS

By | December 15, 2011

Slashgeo linked to an incredible web-based QGIS tutorial last week.  I’ve been looking through it, and so far it is excellent.  It’s not really designed for total newbies – there are other places to get your very first introduction to a desktop GIS.  Instead, this tutorial seems to be aimed at those who are familiar […]

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The Many Faces of OpenStreetMap

By | November 29, 2011

Chances are, you’re not familiar with OpenStreetMap.  The market saturation of Google Maps and Bing Maps is such that they’re the tools we turn to, sometimes without even thinking.  Both these services have an incredibly beatiful and usable design aesthetic, which makes them easy to read.  There’s no real reason why you’d need a third […]

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Typecasting with Field Calculator

By | November 22, 2011

One of the keys to good database planning is correctly anticipating what type of data each field will hold.  If a field is expected to only hold integers, it is best to make it an integer field instead of a float or double field.  Doing so will save space and time, and the database structure […]

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Student un-Projection Projects

By | November 17, 2011

Part of the GIS Day 2011 festivities at Texas A&M University included a student poster display in Evans Libary on the main campus.  There were 29 posters covering a wide range of GIS topics from various classes and departments.  All 29 posters contained a scalebar, a legend, and a North arrow.  But only three contained […]

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GIS Day 2011

By | November 16, 2011

Happy GIS Day everyone!  GIS Day (and Geography awareness week) has certainly gotten more popular over the past year.  The first time I ever heard of it was last year, when a former professor mentioned it on Facebook.  This year, it seems like everyone is celebrating.  Universities are hosting student poster displays, and local governments […]

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Catching Bad Characters

By | October 25, 2011

When loading data into a PostGIS database using shp2pgsql, have you ever gotten this cryptic error? Unable to convert data value to UTF-8 (iconv reports “Invalid or incomplete multibyte or wide character”). Current encoding is “UTF-8”. Try “LATIN1” (Western European), or one of the values described at This means that there is an invalid […]

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A Difference of Projections

By | September 17, 2011

If you divide your time between ArcGIS and QGIS, you may have noticed that they don’t use the exact same projections.  For Northern Colorado, for example, ArcGIS offers “NAD 1983 HARN StatePlane Colorado North FIPS 0501”, while the best QGIS can do is “NAD83(HARN) / Colorado North”.  When projection information doesn’t agree exactly, I get […]

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Book Review: Code

By | August 29, 2011

Code: The Hidden Language of Computer Hardware and Software by Charles Petzold Microsoft Press, 2000 ISBN-13: 978-0735611313 The fact that you’re reading this suggests that you know how computers work.  But that’s only at one level of abstraction.  In the case of the touch/point/click interface, that can be ten or more levels of abstraction above […]

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