7

I'm looking for as detailed as possible topographic data for a certain area and have found information displayed by Google Maps to be far more detailed than what is provided by 7.5 minute maps (from USGS). Does anyone know the source of Google's topography data?

Specifically, I'm looking for data on the Los Angeles area.

  • Specifically, I'm looking for data on the Los Angeles area. – James Dec 1 '14 at 23:29
  • 1
    There is an edit button beneath your question so that you can revise it with additional details like this. – PolyGeo Dec 1 '14 at 23:39
  • 2
    Likely, just as with their sat imagery, there is a variety of sources. Note that just because their map appears more detailed doesn't mean it is. Both could be different interpolations of the same source data, and hillshade effects can go a long way in affecting appearance. – Chris W Dec 1 '14 at 23:48
  • Thanks, PolyGeo, I didn't notice that the first time. Chris, if you look at a hilly area (most notably the Santa Monica Mountains), you can see individual land plots, which I could not find elsewhere. – James Dec 2 '14 at 15:27
7

There is more than one source depending on the area of interest around the globe.

Google Maps is the terrain layer, which provides a shaded relief (aka hillshade) view of the topography derived from a digital elevation model. Google has done a nice job generating a visually pleasing terrain layer, and we use it for all of our Google Maps-based interfaces in OpenTopography. Google appears to use a range of digital elevation model data sources to derive the terrain layer. Throughout the US, it appears that the terrain layer comes from either 10 or 30 m (1/3 arc-second & 1 arc-second respectively) DEMs from the USGS National Elevation Dataset (NED). Globally the terrain data appear to be derived from either Shuttle Radar Topography Mission (SRTM) data or something like the NOAA Global Land One-km Base Elevation Project (GLOBE) dataset. Recently however, I’ve begun to notice higher resolution data in the Google Maps terrain layer. These higher-resolution data are localized, and are patched into the terrain layer among the standard 10 and 30 m derived images, but they are impressive when you find them. Based on the location of these patches of high-resolution terrain, and their appearance, it is pretty easy to deduce that Google is now incorporating bare earth LiDAR digital elevation models into the Google Maps terrain layer.

Thus far, I’ve noticed high-resolution data in downtown Portland, OR, the greater Los Angeles area, and Mount Saint Helens in Washington. There may be other examples of LiDAR-derived terrain

Source: http://www.opentopography.org/blog/lidar-beginning-appear-google-maps-terrain-layer

  • I think, from your post, that it is the LiDAR data which I am interested in. Thanks for your help, Mapperz. By the way, it is in many many more places than only Portland and LA, although I don't think it quite covers the U.S. – James Dec 2 '14 at 15:33
2

In the US, it appears that Google is using LiDAR data where it is available. I ran some tests in two areas. One where I had actual LiDAR data, the other where I had field survey data. Google Elevation data was amazingly accurate.

You can read more on my blog - https://chasmtech.wordpress.com/2017/01/17/civil-site-design-satellite-to-surface-feature-is-amazingly-accurate/

  • 2
    put some more detail from your blog post in the answer. In case your blog link doesn't work in the future. – Mattropolis Jul 21 '17 at 20:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.