NASA/Japan Release Terrain Data – Google Earth’s is Better

One of the top stories yesterday was how NASA and Japan have released the data from their ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) satellite on the Internet – for free. What is significant about this is that the data covers 99% of the entire Earth’s landmass terrain – verses 80% from the SRTM (Shuttle Radar Topography Mission) – which was the best previously available free public terrain data. ASTER’s data is also higher resolution than SRTM which had a base resolution of 90m and at best 30m. ASTER’s resolution has a base resolution of 30m, and can be higher under certain conditions (up to 7-10m – see documentation). The data released comes from over 1.3 million photos taken by the Aster satellite.
So, will Google Earth make use of this new ASTER data? The answer is: only a portion of the data. Google Earth already has terrain data in many areas that has higher resolution than the data provided by Aster (see below). However, ASTER provides data for remote locations (particularly high latitude regions) which previously wasn’t readily available in these resolutions. And, Google Earth still has regions (such as remote pacific islands) which are using SRTM data (90m resolution). So, I’m sure Google will consider using the new data to improve the resolution in some regions. IF, they don’t already have another source with better resolution. By the way, I asked Google about ASTER, and got the standard reply that they don’t have anything to announce at this time (i.e. “no comment”).
As far back as the February 2007, Google started introducing significantly higher resolution terrain. At that time they introduced 10m resolution terrain for the Swiss Alps, followed a few months later by 10m resolution terrain for the US and Canary Islands (read GEB review). In the more than two years since, Google has added millions of square kilometers of higher resolution terrain. Some of the terrain is much higher resolution. For example, the state of West Virginia has 3m resolution. Back in April of 2008, the city of Bergen, Norway got very high resolution data – which appeared to be based on LiDAR. Recently, Oslo, Norway also got very high resolution terrain data (also seemingly LiDAR) as well as 3D Buildings.
In recent months, Google has been regularly adding cities and countries with higher resolution terrain with nearly every imagery update (see for example the May 2009 update – new terrain is listed at the bottom). Google is no longer releasing details on the resolution of the data. Probably because the terrain resolution varies for each city. One drawback to higher resolution terrain is the data starts capturing things like buildings – not just the land – and it gets to be harder to tell the difference between good data and noise. But, the ability to see the terrain more accurately is well worth this risk in my opinion.
An important tip if you’re interested in Google Earth’s terrain data: Under the Google Earth Options is a slider called “Terrain Quality”. If you push that slider to the right, you can see higher resolution terrain. A word of caution: higher quality terrain means more 3D data – which can slow down your update speeds in Google Earth. After viewing higher resolution terrain, I recommend putting the slider back to closer to the middle for every day use. If you have a faster computer with a powerful video card, you might be able to get away with a higher setting. (Read more tips about optimizing GE performance).

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Comments

  1. After reading the news yesterday I was thinking about the same question (will and in what degree will the data be mirrored to Google Earth) and hereby my thanks to you for writing an article that answered to my question. Thanks!

  2. Will NASA use it in WORL WIND ?

  3. Can you be sure and let us know when the South Pacific region is updated. Some of us sailor types need higher resolution images so we can spend more time dreaming of sailing there!
    Thanks!
    -p

  4. Frank Taylor says:

    @brancin: I’m sure Worldwind will make use of the data as well.
    @Patrick: By all means, I’ll mention if they improve data for the Pacific islands. As a sailor myself, who is about to leave for a circumnavigation – including those waters, I’m very interested in seeing the improvements. Follow my web site http://tahinaexpedition.com for the best way to learn about sailing using Google Earth.

  5. scott s. says:

    I went to the linked sites and couldn’t find any way to get the data for free unless you have a NASA research agreement/contract. I take it the “resolution” cited is horizontal. Users of data such as NED are aware of digitization artifacts that reduce vertical accuracy and resolution, often resulting in “layer cake” or “staircase” effect in the rasters. Satellite-based sensors are subject to their own errors, and it would be interesting to see a comparison with SRTM for data holes and other problems.

  6. Problem is they did not release the new ASTER data to public domain. So you can only use it for personal use. Thanks but no thanks.

  7. If ASTER GDEM is used by Google Earth it will improve a few areas but make many other areas worse. GDEM’s true resolution is 100-120m, its general quality is lower than SRTM, and for most of north Eurasia (where there is no SRTM, NED or CDED) its quality is poor with some very large artifacts. ASTER GDEM version 1 is research grade. Perhaps future versions will be better.

  8. It doesn’t seem very user orientated, it’s rather awkward to get anything out of it. At least that’s how it looks to me?

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