Archive For The “Tutorial” Category

Ubuntu GIS from Scratch: Step Six – QGIS

Welcome to Step Six in our exploration of open source GIS using Ubuntu. In the previous installments, we uploaded some spatial data into a PostGIS database, and experimented with spatial SQL. Finally, we’re ready to install QGIS, the most popular open source GIS desktop available. QGIS is a lot like ESRI’s ArcMap, in that it [...]

Read more »

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 [...]

Read more »

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 [...]

Read more »

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 [...]

Read more »

Ubuntu GIS from Scratch: Step 2 – GEOS and GDAL

Welcome to Step Two 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 previous step). The spatial extension for PostgreSQL is PostGIS, which we will eventually be installing. But before we can get [...]

Read more »

Ubuntu GIS from Scratch: Step 1 – PostgreSQL

After a recent hard drive crash, I decided to try out Ubuntu, the most popular consumer Linux distribution. Ubuntu has become popular because it is more lenient than other distributions with regard to proprietary software – it can use Flash and play mp3s out of the box, without installing additional software. Ubuntu, like other Linux [...]

Read more »

Sun Glints in ArcMap

Aileen Buckley, at the ESRI Mapping Center, has released a new tutorial on creating what she calls “sun glints”.  These are the reflective glows you sometimes see on water bodies in aerial photographs.  In essence, it’s a tutorial on creating gradient fills in ArcMap – a neat effect that cartographers don’t get to use very [...]

Read more »

Typecasting with Field Calculator

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 [...]

Read more »

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 [...]

Read more »

A Difference of Projections

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 [...]

Read more »