Digital Geography

GDEM V3 vs SRTM 1: a comparison

Some time has past since I last wrote a DEM comparison, comparing ALOS World with SRTM 1 and GDEM V2 with SRTM 3. But as NASA and METI released the lates version of the ASTER GDEM dataset, I will compare this once again for a certain area in central Mongolia. But this time, the competitor will be SRTM 1.

Geocoding with Microsoft’s Azure Maps

API’s are getting more and more important as some (maybe the majority?) of GIS users don’t want to handle large datasets, don’t want to care about addresses and geo-coordinates, don’t want to create an own routing algorithm… As most of you might use Google, OSM or HERE for geocoding purposes I would like to introduce Azure Maps for this as well.

Copernicus, Sentinel and your favourite GIS

The Copernicus Program provides an interesting alternative data source for your work with Landsat data… Sentinel images: Copernicus will deliver an unprecedented volume of free data, provide new operational services and foster new business opportunities and job creation. The data itself is collected since 2014 (Sentinel 1A) and the operation is scheduled to deliver data till 2020 at least. But how to get the data into the GIS of your choice.

A Digital Earth: the Potential of Data Brokers

Introduction In my previous two posts I introduced the Cloud based data broker technology ERDDAP and demonstrated how one can use it to obtain geo-spatial scientific environmental data: Access sensor data on an buoy located in the Irish Sea . Get and display weather forecast data from the Global Forecast System (GFS). The use of data brokers to unify data catalogues is an approach taken by both the National Oceanic and Atmospheric Administration of the USA (ERDDAP) and the intergovernmental Group on Earth Observation (GEO Discovery and Access Broker). In this post I discuss the potential impact of this type…

Short Announcement: New Sentinel Cloudless Atlas

Mapbox created a cloudless Landsat map in 2013. That was a huge step for all the webmapping enthusiasts as we got a composit image of the world with stunning ground resolution and still cloudless! Now EOX, a company based in Vienna, provided a similar product called Sentinel Cloudless. And it is “for free”.

ALOS World 3D V1.1 vs. SRTM1

Some days ago a new version of the ALOS 30m DEM was released: Void pixels due to clouds and snow pixels within 60 deg. of north and south latitudes in Version 1 were complemented by existing DEMs. Out of the areas are same with Version 1 product. As we already compared ALOS with SRTM-1(I saw the ALOS DEM as “the winner”) I am now interested in how this performs in a another setting. We are changing our focus from Mongolia to Germany and check how the new ALOS DEM works compared with SRTM 1.

Observing deforestation with Sentinel-1

While preparing for an upcoming presentation at the annual meeting of the American Geophysical Union (AGU) I came across a topic that I thought might make an interesting blog post.  The presentation is about using data from the Sentinel-1 mission for Earth Science applications.  The Sentinel-1 spacecraft are C-band SAR systems launched and operated by the European Space Agency (ESA).  An innovative aspect of this mission is that the collection scenario devised by ESA is systematic and very broad in coverage.  Using Sentinel-1 we can monitor Earth using SAR data like never before.

Do you need open data? Ask for it.

The well-known Q/A-forum StackExchange has started a new “Open Data” section. Users can ask for needed datasets and get feedback from the great StackExchange community. Especially for our GIS and webmapping readers this is good news. Often the methodology isn’t the core problem of dealing with scientific or business issues. Often it’s more or less a lack of proper open datasets to run visualization and analyses.

The Coup in Turkey: the Twitter Perspective

The coup/attempt in Turkey kept me up from going to sleep after the two nice hours of “Back to the Future” on German television. So despite of the tragedy behind it: twitter was exploding as I watched the news coming in. I was interested in the timeline of tweets, locations and “everything”. I downloaded about 10Gb of twitter data and here is my analysis for everything ‘#turkey’ from Friday till Monday.

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.

Import OSM Data Into A PostGIS Database (The Easy Way)

I often find myself in a situation where I want to work with large areas and datasets of OpenStreetMap data. No matter if you want to use them in a QGIS map or create custom map tiles in Tilemill, with the Overpass API you quickly run into performance issues. Imposm is a great tool to overcome that situation, so you can load OSM extracts (worldfiles in pbf format) with a custom data mapping into a PostGIS enabled PostgreSQL database. The downside: It is hard to set up if you are not a database and system admin guru. This is where…