Digital Geography

planlauf/TERRAIN – a lightweight 3D DEM viewer for daily usage

The visualization and interpolation of 3D terrain (point) data (DEM or DOM) could be a hard task for current GIS software and small to midsize hardware. One thing is the huge possible amount of points and their precision when it comes to airborne or terrestrial LIDAR data with point density < 5m and big areas of interest. Another thing is the rendering performance once the user started his exploration of such a huge dataset. There are several open source and proprietary software solutions and specialized software for several industries. In the following I’ll introduce you to planlauf/TERRAIN, a lightweight DEM…

Short Announcement: SRTM 1 Data Worldwide

The digital elevation dataset resulting from the SRT Mission in the year 2000 is probably the most widely used digital elevation dataset in the world. It was first released with a 90 at ground resolution in a more or less global level (56° S to 60° N). In 2014 the White House announced the release of the 30 m original solution dataset. So they released parts of the dataset one-by-one. Our author Christoph just mentioned an update via Twitter.

Some ways to produce high-res DEMs – tools and data

Many of us use digital elevation models (DEMs) for a whole bunch of different applications. There are some standard products which everyone should know, like SRTM1, SRTM3, ASTER, GLOBE or ETOPO1 for the land surface or GEBCO for bathymetry. However, they have a relatively low resolution and are therefore not suitable for all purposes. During the last few years there has been a huge progress in producing much better DEMs, especially local ones, using a wide range of techniques like LiDAR, photogrammetry, image correlation, structure-from-motion (SFM) etc. Some of these techniques make use of powerful, but expensive equipment (e.g., LiDAR),…

SRTM-1 (1 Arc second) now available with large global coverage

With this post I would like to come back on a topic from September 2014. In this blog post on Digital-Geography I announced that from September 2014 until September 2015 high-resultion SRTM-data will be provided for free by the USGS. We also announced the estimated release dates for certain regions around the globe.     After checking the progress of the release in EarthExplorer, I realized that the release is proceeding much faster than expected. Till this day, only Norhteast Africa is missing. Parts of Canada, Russia, Greenland, Scandinavia, Artica and Antarctica are missing due to the SRTM coverage limit of…

DEM comparison: SRTM 3 vs. ASTER GDEM v2

Let’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.

Announcement: Realease of worldwide high-resultion SRTM-data (30m)

The White House announced on September 23th during the United Nations Heads of State Climate Summit in New York that they are going to release the high-resolution images of SRTM globally. Until now, the high-resolution imagery were only available for US-areas. All other countries had lower resolution imagery. Due to this release the 30m x 30m imagery will be available globally and substitute the 90m x 90m data. After its release the data will be accessible on EarthExplorer by the US Geological Service (USGS). Unfortunately they didn’t announce an exact release date (only “will be released globally over the next year”). That…

Peakfinder – identify the hills around you

Peakfinder.org is a fascinating website. It’s not new, but I just came across it few days ago by a recommendation of @callanbentley. It appears very simple, very clever and very beautiful. The site allows you to find peaks (mountains and hills) in your surroundings or wherever you want. Basically, it draws a simple line sketch of the horizon as you see it from your current position and names all the peaks in your sight. I could spend hours on this.  The website’s layout is amazing. It’s calm, pure and perfectly organized. Some options include searching for peaks from a database and…

short announcement: TopoToolbox 2: Geomorphometry made easy in MATLAB

< p align=”justify”>Digital elevation models (DEMs) exist today for the entire globe with consistent quality. Improvements in sensors and data processing give a clue that in the future elevation data will be available in even better spatial resolution and accuracy. Discovering the richness of information inherent in DEMs should thus be supported by good software. Here, I want to give a brief account of TopoToolbox 2, the second version of a MATLAB toolbox for exploring and analyzing DEMs. Dirk Scherler from Caltech and I have been working on many changes to the previous version to make TopoToolbox faster, more memory…

Innovative SRTM Download

It’s been a couple weeks since I’ve posted here, but I just found something I wanted to pass along. If you work with geospatial data, you are probably familiar with the Shuttle Radar Topography Mission (SRTM) that collected elevation data over much of Earth. These data are available from a number of interfaces on the Web, but this is one of the nicest, and most innovative, ones I’ve found. SRTM Tile Grabber Just find the spot on Earth you are interested in and you can download the SRTM data for that area as a geotiff. I think this is probably…

Free Sources of Geospatial Raster Data

I’m always looking for good sources of free data, so I thought I would post a few here in case they were useful to others. The sources listed below tend to be larger providers of regional to global level data, however, please post suggestions in the comments if there are other sources you like and think should be added. I had initially planned to include vector data here, but I think that will be another post as this one got quite long. SAR Data Free Synthetic Aperture Radar data can be some of the hardest to find, but it is…