Thinking in GIS

GDAL is most likely the most powerfull GIS toolset out there, with very geekish features that may seem complicated at first, but become extremely powerful and simple at the same time once you master them. One of these features I most like is the virtual format concept, valid both for raster data sources (GDAL) and for vectorial data sources (OGR).Basically GDAL gives to the user a very simple mechanism to create virtual formats from some different sources.Let's analyze this feature, with a couple of samples derived from real world scenarios I have been envolved in the last weeks.GDAL gives the...
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There is a recurring question at GIS mailing lists, forum and at some extent in my mailbox: what is the best way to master Python for developing geospatial applications?I myself had this question far away in 2006 when I started switching from proprietarysoftware to Open Source, and had identified in Python the way to go.In this post I will try to quickly summarize what is the best way to go in my opinion.If you are completely new to Python, first things to check out, are some very basic and popular resources, like these ones:the official Python tutorialthe "Dive into Python...
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Today in the GDAL mailing list Frank Warmerdam has announced that GDAL 1.9.0 has finally been released.Being a major new release, it offers many new features, but what I was waiting for is the support for Esri File GDB and Google Fusion Table.So I couldn't resist to install it and giving a try.For using the File Geodatabase driver I had to dowload the Esri File Geodatabase API (you need to be registered for downloading it).It was then just a matter of setting the value of the library path in the LD_LIBRARY_PATH variable, and using the --with-fgdb GDAL configuration option when...
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If you have ever tried to interact with a WFS (via a browser, or curl, or OpenLayers or whatever), you are fully aware that it has alway been a pain to interact with, and until now the only Python library that made life simpler was the excellent OWSlib by Sean Gillies (that, BTW, will deserve itself another post at this blog in the next weeks).But since some weeks, from the release of the GDAL version 1.8.0, a new toolset is available to GIS users and developers via the new included GDAL WFS Driver (that will now make good company to...
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These are my quick notes for installing Oracle Instant Client on a Linux box (currently I have tested this on a Ubuntu 10.10 64 bit box and with Oracle 11.2 and GDAL 1.8.0), and then configuring GDAL for using Oracle (OCI and GeoRaster drivers support).Finally I will show how to configure GeoDjango to use an Oracle spatial database by using the Cx_Oracle Python library.First download Oracle Client files from here or here if you are on a 64 bit architecture.You need to download the following 3 zip archives:~/software/oracle$ lsinstantclient-basic-linux-x86-64-11.2.0.2.0.zip instantclient-sdk-linux-x86-64-11.2.0.2.0.zip instantclient-sqlplus-linux-x86-64-11.2.0.2.0.zipThen extract the archives to a location...
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Last week I have been attending the GFOSS Day 2010 in Foligno, basically the FOSS4G Italian Event that is held every year.The conference was split in two days: in the first days a good number of workshop and tutorials were given, related to a number of geospatial technologies.In the second day there were the instutional talks, mostly related on the open data theme.This year I myself gave two talks at the conference: in the first day, togheter with Alessandro Pasotti, we have been giving an extended tutorial about developing geospatial software with Python, here are the slides:Developing Geospatial software with...
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In the last months there has been a plenty of activity in the non relational (NoSQL) database world.NoSQL database tries to solve 3 main RDBMS problems:Scalability, for example the ability to automatically partitioning data across multiple machinesPerformance, in some case RDBMS can be very slowFixed schema: RDBMS have nice goodness (referential integrity, relationships, triggers...) but force you to store any object to a fixed schema (migrations are a pain!)Basically there are several different kinds of NoSQL database:Key/Value (Scalaris, Tokio Cabinet, Voldemort): store data in key/value pairs: very efficient for performance and higly scalable, but difficult to query and to implement...
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This time i will introduce a really brilliant framework that every serious Web/GIS developers should be aware of: GeoDjango.Django is a Python Web framework for agile developers. It implements best web frameworks practices like coding by convention, MVC, ORM, REST, URL dispatcher and so on. Django is for Python what Rails is for Ruby, Grails is for Java, and MonoRail (and now ASP.NET MVC) is for .NET.GeoDjango is a Django application that is now included in the Django trunk with a lot of excellent stuff for developing GIS web application.GeoDjango Building BlocksGeoDjango installation is based on Python, Django and two...
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My friend Diego Guidi is the smartest GIS/.NET developer I personally know here in Italy. He is the developer of NetTopologySuite, the port in the .NET world of the popular Java's JTS Topology Suite from VIVID Solutions. I wanted, sooner or later, write some stuff here about WMS and TMS, and now I am very happy that Diego asked me to publish this brilliant article about this topic.First of all, let me thanks Paolo for hosting this post! I hope that this article can be interesting and useful like other stuff that you can find here...IntroductionThere are a lot of...
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