Digital Geography

DEM comparison: SRTM 3 vs. ASTER GDEM v2

ASTER vs SRTMLet’s get ready to rumble! No, just kidding. We are all excited about the recent message from the white house: SRTM “1” (1 equals 1 arcsecond, whereas 3 was indicating the 3 arcsecond a.k.a. 90m DEM) or the official title SRTM-2 will be available for free in the next months (orig. here, dg here). So why is it so important? Most DEM-interested people will answer: “Use the ASTER DEM if you need 30m!”. But let us have a closer look on both systems and how they perform.

QGIS 2.6 Feature Freeze

Screenshot from 2014-09-20 12:13:31

Are you curious about QGIS 2.6? Well on Friday (9-26) QGIS development goes into feature freeze and focus will shift towards fixing bugs and enhancing stability. What can we expect from the upcoming release. Read on to find some interesting news.

QGIS 2.6 – Sneak Peak

Picker

The release of QGIS 2.6 is planned for October 24, but you don’t have to wait to test new functions in development. In this post I’ll look closer on two new features that in my mind will make GIS life easier, even if some improvements should be made with the first of the new features described here.

Exploring OSM Israel/Palestine

Screenshot from 2014-07-27 10:25:23

In this post I’ll show how to explore (or data mine) Open Street Map data and use features off-line that normally can be hard to get. Many use http://download.geofabrik.de to download zipped shapefiles to be used directly in GIS systems, but are surprised when it does not contain as much data as the same area in Open Street Map on-line. You can still use geofabrik.de but download the *.osm.bz2 files instead. They include raw data from OSM that needs to be processed in order to be used in QGIS or other GIS applications. In QGIS there’s a tool in the…

Military Expenditure on a map

Screenshot from 2014-07-17 14:34:15

Statistical data for a geographer is fun! War is not! Regardless what you think of the military it never hurts to be informed, so… Lets play a bit with military expenditure statistics. I’m using data from SIPRI (Stockholm International Peace Research Institute), which covers military expenditure for regions and countries based on for instance GDP. The data is in Excel format (.xlsx) which is a problem for QGIS, so it has to be converted to a format that QGIS understands. First however some other issues must be addressed. In order to use the years as field names they must be…

regular spaced points… interpolation madness…

rasterized point shapefile in QGISThe geodata department of the city of Berlin offers a great portfolio of free geodata for everyone to use. One dataset is the result of some LIDAR measurements and is offered as a txt with x,y and d values. This is commonly known as xyz data but should not be mistaken as a simple whatever-delimited text file. This dataset is regular spaced and therefore can be threatened easily with QGIS. But let me first show you some interpolation results which can be produced as well. Interpolational madness If you want to create raster data from a point shapefile or a…

reproject and filetype change in python/pyqgis for QGIS plugin

featured_2In my current work on the qgis2leaf plugin I had the idea to place raster data on a leaflet map as an image overlay. With this in mind and looking at a webmap I needed to consider a good filesize, a strict projection of EPSG:4326 and a strict filetype as well. So decision was: projecting everythin to EPSG:4326 and changing file type to *.jpg. I know, how to do this in the Terminal and in QGIS. But what options do you have using python/ pyqgis only? Terminal For doing this work in the terminal/shell/command line the one and only choice…

Top 5 QGIS Plugins

GeoSearch - Routes

I have been using QGIS 2.2 for most of my GIS work for about 3 months now, so I have noticed that I keep on using some plugins over and over and I really wouldn’t be able live without them. So here is a list of my favorite top 5 QGIS plugins! Top 5 QGIS Plugins 1. OpenLayers plugin It was love at first use for the OpenLayers plugin.  It allows the user to load basemap from a different provides like Google, Bing, Yahoo, OSM (OpenStreetMap), Apple (I have NO idea what someone would want it) and Stamen. Now I…

Vintage Themed Maps in QGIS

Vintage_QGIS_Burn

Vintage Design in QGIS 2.2 Hello again! Thanks for taking a look at this post on how to create a Vintage Themed Maps in QGIS 2.2. Now for this process I am using QGIS 2.2 on Ubuntu 14.04, I only mention this because I have never compared the Linux and Windows version to see if there are any difference between the two versions. Furthermore, I would like to state that I originally the idea for this post from this Blog last year, so please take the time to look at it. Also, if you haven’t looked at my original post…

ILWIS GIS – Tutorial I [Introduction]

ILWIS Logo

Today I’ll start with a new series of tutorials for an open Source GIS called “ILWIS GIS“. ILWIS is the short term for “Integrated Land and Water Information System” developed at the ITC Enschede and distributed under the GNU General public license as open Source GIS since 2007. It’s purposes is designed for geoecological questions. It can handle both, vector- and rasterdata.     If you’re interessted in ILWIS you can download the newest version here: http://52north.org/communities/ilwis/ilwis-open/download. The software package is available for the following operation systems: Windows and with the use of additional software on Linux and Mac OS X. The language…

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