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.

NASAs 2014 Budget: the launching of a crisis?

Following sequestration and bitter budget wars in Washington NASA find itself in a difficult position. NASA has proposed a budget of $17.715 billion, down from $17.893B last year. The House passed a bipartisan bill this last week: slight increases in Earth Science are proposed as are cuts in Planetary Science. Exploration receives more than $300 million more in FY2014 than FY2012; Space Operations slightly less in FY2014 than FY2012. The International Space Station continues to deplete budgets by more than $3B a year (rising to $3.5B by 2018). Planetary Scientists are not happy with the budget. Really not happy (though it should be noted that…

Landsat-8: how not to plan a mission (Part 1: policy)

I was recently reading the 2012 article by James R. Irons and colleagues describing the Landsat-8 mission (or Landsat Data Continuity Mission, LDCM, as it was then called)¹. They do a very good job in describing the mission from planning to inception. I like to think of this paper as a guide to how not to plan an Earth Observation mission. Here’s my reasoning. Landsat-8’s difficult conception The logic behind Landsat-8 (L8) is impeccable. US agencies had realised that operational remote sensing, including at the Department of Agriculture and the United States Geological Survey (USGS), not to mention science, relied on…

Rainfall and weather data on GoogleEarth

On Saturday, some villages near my hometown suffered heavy rains. Up to 100 l/m² arrived during the afternoon and evening in Kirchhasel and other places in central Thuringia. Small streams became rivers and flash flooding occurred, damaging houses, roads, and cars. The local newspaper has an impressive pic dump. Locals say this have been the worst flooding for at least 40 years, so pretty much excitement here, we are not really used to this despite the river Saale caused some heavy floodings in the past. Now it looks like thunderstorms will arrive again: So I had a reason to think…

short announce: Reverb @NASA the new WIST

Sorry to talk about this important tool with a little delay. As I was lecturing at the university I was using the Warehouse Inventory Search Tool (WIST) by NASA to collect my raster data and download them. It was a great tool but looked a little old. The biggest difference to services like or the SRTM Tile Grabber is, that most data was ordered and delivered by FTP. It was not a big deal as most data was available for free but I think for a lot of users this was not “convenient” enough… Nevertheless Reverb- the new WIST-…

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…

Landsat Data Continuity Mission

Looking Back Most people using GIS or remote sensing data came across the data obtained by the landsat satellite family. It all started with the Landsat 1 mission on July 23, 1972. The Landsat missions aquired millions of pictures which made available to public usage in 1992. Sensors developed and provided more and more details in terms of spectral and ground resolution.

The End of the Landsat 5 Era

If you have been working in the space remote sensing community for any length of time you have almost certainly crossed paths with Landsat 5. After 29 years of watching Earth, the U.S. Geological Survey announced that Landsat 5 would be retired slowly over the coming months. Of course most people are looking forward to Landsat 8 (LDCM), but it is worth it to look back for a bit on Landsat 5, this stalwart icon of Earth remote sensing. More information from the USGS can be found at the official release As always, thanks for reading.

Version 2 ASTER Data now available

Since one month, the 2nd version collection data of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) are now available online. This data is now worldwide available for free and is made possible by the NASA and the METI. Even if according to NASA the data is produced with the same gridding as the first version, some large improvements have been made, such as: