Archive For The “PostGIS” Category

Ubuntu GIS from Scratch: Step 5 – Spatial SQL

Welcome to Step Five in our exploration of open source GIS using Ubuntu. In the previous installment, we uploaded some spatial data into a PostGIS. database. The next logical step is to install QGIS and add start visually analyzing this data, which we’ll get to in Step Six. But before that, I wanted to take [...]

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Ubuntu GIS from Scratch: Step 4 – Loading Data.

(Note – this post was updated on October 28 to include new information!) Welcome to Step Four in our exploration of open source GIS using Ubuntu. In the previous installment, we spatially extended our PostgreSQL database server with PostGIS. Now we’re ready to load some geographical data into our database. PostGIS includes a tool called [...]

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Ubuntu GIS from Scratch: Step 3 – PostGIS

Welcome to Step Three in our exploration of open source GIS using Ubuntu. In order to grasp the full power of GIS, we need to spatially extend our database (PostgreSQL, which was installed in the first step). The spatial extension for PostgreSQL is PostGIS. In the second step, we installed GEOS and GDAL, two major [...]

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Catching Bad Characters

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 http://www.postgresql.org/docs/current/static/multibyte.html. This means that there is an invalid [...]

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Trendspotting

British GIS site web-gis.co.uk is currently hosting a poll about GIS data formats.  Not too many people have voted yet, but a clear trend is already emerging.  The data suggests that PostGIS has been gaining a lot of ground, eclipsing other popular proprietary data formats.  Here’s the current breakdown: PostgreSQL/PostGIS – 17 votes, 65.4% Proprietary [...]

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PostGIS Projection Project

PostGIS is a wonderful suite of tools, which really anchors the open source web mapping toolkit.  However, it doesn’t always integrate well with an ArcGIS desktop environment.  One obvious source of conflict relates to projections – most of ArcGIS’s projections are infinitesimally different than their real world counterparts.  As an example, consider the Washington North [...]

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