Digital Geography

Some ways to produce topographic swath profiles

For a geomorphological study that I am working on I want to produce topographic swath profiles across a mountain range, that is, I want the average elevation along a profile plus the min and max values within a certain distance of said profile. I have used three different methods to achieve that and found some nice resources that I’d like to share with you: GMT – Generic Mapping Tools GMT is a powerful suite of command-line small programs to manipulate all kinds of geographic data (Wessel and Smith, 1998; Wessel et al., 2013). A walk through on how to produce…

PostgreSQL and PostGIS: A brief introduction

You probably seen this already (maybe on your very own PC as well): A folder with shape files. Well we’re living in the 21st century and I do have and use those folders still. After a talk of Sebastian Meier at Maptime Berlin I was convinced and started to work with a databases instead of folders. So let me show you how to install PostgreSQL along with PostGIS on Ubuntu and Windows, how to get data into it, import OSM data and how to connect it with QGIS/ArcGIS.

Accessing Landsat and Sentinel-2 on Amazon Web services

The cloud has made it easier to process large amount of data, and satellite imagery processing benefits from cloud processing too. One of the cloud services that offers access to satellite images, and abilities to process them in the cloud – no more need to download it to your computer and process it there – is Amazon Web Services. If you’ve never worked with cloud processing, getting started with AWS can be a bit daunting. This tutorial gives beginners an introduction to accessing satellite images – Landsat and Sentinel-2 – on AWS.

Filter Leaflet Maps with a Slider

If you create maps you always need to ask yourself: how can I make it as easy as possible to read and still have anything I need in my map… or in short: reduction and abstraction. There are different approaches out there when it comes to web maps. Let me show you how to reduce the number of map elements with a slider in leaflet to filter your data interactively.

What is better: a map or a picture?

I was reading an article entitled “China, the megalopolis of 110 million inhabitants that impresses the world” on a popular online journal (see article) and after a dozen lines read: “Beijing is already surrounded by six ring roads, [… ] but the seventh will be 940 kilometers long.” How many are 940 km for example along a circle, as the Circular Highway of Milan?

Routing in QGIS… with OSM

Routing with Google is quite cool as the database/network is probably the best currently available. But the terms of services limit the possible usage. So what about OpenStreetMap? By figuring out how to use OSM for routing I found it much easier to get routes into QGIS with OSM compared to the Google way. Check it out….

CSV to SHP with Python

Python is a well established script language in the GIS/geodata world. And as a Facebook friend asked how to read csvs with Python I thought about “How to convert a csv to a shp with Python?”. Keeping in mind that most GPS solutions and many internet tools offers a csv export and it’s common in any stats/spreadsheet program this can be a handy solution for your everyday life. See my solution here…

D3: My First Webmap

I always watched those stunning examples created with D3 by Mike Bostock, I liked Ralf’s blog posts here and I always thought to myself: get yourself together and create one for your own. But to say it straight: I haven’t figured it out… But yesterday I stumbled upon this nice, not so short post of MappingGIS.com and I would like to share my learning process here. So let’s start …

How to create a wind map in QGIS

A few days ago I saw Franz Leonardo’s post on the ArcGIS group on facebook: He visualised wind speed and direction in ArcGIS for a wind map and I thought by myself: let’s do it with QGIS… Here is the tutorial which covers some aspects of interpolation, symbol levels, classification and formulas…

Create A Raster Layer Index With QGIS And GDAL

When working with raster datasets, it is hard to keep an overview of the raster files in use and their coverage. Most raster data providers may keep metadata in the filename itself, like path, row and a timestamp. But for more convenience, it is possible to create an index of your raster maps. This article will show you, how to accomplish this in QGIS or with the Terminal.