

NGA releases high-resolution elevation data to public - liotier
https://www1.nga.mil/MediaRoom/LeadingStories/Pages/NGAreleaseshigh-resolutionelevationdatatopublic.aspx

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mrgriscom
Wow this is huge news. I wonder what higher resolution the DoD now has at
their disposal to prompt them to release this.

For any potential consumers of the data, be aware the SRTM has significant
gaps in coverage: nothing above latitude N61 or below S56, and also extensive
voids in mountainous areas (typically the most interesting part!) and also in
deserts.

This guy
[[http://www.viewfinderpanoramas.org/dem3.html](http://www.viewfinderpanoramas.org/dem3.html)]
(90's web design notwithstanding) has done amazing work in filling these gaps
to turn SRTM into a truly global dataset. I wonder if he's kicking himself
that he's now about to sink another few years of his life upgrading everything
to 1".

If anyone wants to casually peruse the (old 3") data, I found a rather nice
rendering here [[http://maps-for-free.com/](http://maps-for-free.com/)], and
was inspired to do my own take
[[http://mrgris.com/projects/oilslick/](http://mrgris.com/projects/oilslick/)].

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r0muald
oilslick is really neat, I find it both pleasing to look at and actually
useful to view the full elevation range. Is there any common geospatial
software that includes oilslick out of the box?

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mrgriscom
I doubt it; I only finished it last week. But the map tiles are hosted on S3
and free to use as a custom map layer in Leaflet/OpenLayers/GMaps API.

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carlob
Now it would be great to integrate this data into OSM to get navigation for
bikes that takes slopes into account: this is the shortest route, this is the
fastest considering slope, this is the sportiest…

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thrownaway2424
SRTM data is nearly useless for that purpose. I had a run at this exact
application a few years ago and it was quite an exercise in frustration. The
resolution of the data is adequate, but there are artifacts related to the way
the data was collected and processed. There are discontinuous edges throughout
the data. Also, of course, the data is not the elevation along a route.
Bridges and other things over or under which one might ride a bicycle must be
accounted for externally. Even roads in trenches or cuts need special
attention.

I think the only way to make such an application work is to combine the
elevation data of numerous sources, SRTM being just one. The most valuable
source would be the ambient pressure sensors in mobile phones, which are next
to useless for absolute altitude but are excellent for relative altitude as
you move along a path, and of course they have GPS so you also know the path
taken.

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carlob
This is really really interesting. I was curious as to why I hadn't seen any
execution of this pretty obvious idea, now I know.

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maxerickson
[http://cycle.travel/](http://cycle.travel/) and
[https://www.komoot.de/](https://www.komoot.de/) both take elevation into
account (and rely on OSM data for routing).

I guess they are probably supplementing the SRTM data where possible though
(but they are almost certainly falling back to it in places).

~~~
thrownaway2424
cycle.travel/map is really nice. I remember there was (years ago) a nifty
cycling map of the city of Atlanta, which included a unique triangular control
that allowed the user to trade off climbing vs. distance vs. safety (on-road
or off, bike lanes, etc). It was based on Google tiles and routes but had its
own elevation data.

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shawn-butler
The US govt has also been relaxing the export restriction on high-resolution
imagery as well.

DoCommerce gave digital globe permission to sell 0.31 m for b&w band and 1 m
for multispectral bands from WorldView-3 beginning in Feb 2015 I think.

EDIT: [http://worldview3.digitalglobe.com](http://worldview3.digitalglobe.com)
added link to microsite. Couldn't find quick link to relaxing of export
restrictions but I am 99% sure it was announced months ago.

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twistedpair
Odd, I downloaded and used all the 1 arc second data back in 2007. How is this
new? They originally released two products, the 1" and 3" data.

The original 1" data IS 30m lateral resolution (12,742,000m * pi)/(360 deg *
3600 arcsec/deg) = 30.88m

Odd that they're now naming releases after meters and not the previous arc
seconds.

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michael_h
This new 1" release is for the entire planet, not just the US.

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twistedpair
Touche. The link of interest would then be:
[http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/](http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/)

Where the current 7 regions are:
[http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/Region_definiti...](http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/Region_definition.jpg)

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exDM69
Great news but doesn't tell me where can I download the dataset from?

Is it available to non-US citizens too?

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twistedpair
It's been available via FTP for at least 7 years. Perhaps they are now
releasing some version that's higher resolution than the prior 1", 65GB tile
dump.

The date in the data version history is "02/14/05" for this release.

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jcr83
No, this data has not been released yet.

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mrfusion
Could someone write a program to find the perfect sledding hill near a
location?

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hughes
For context, this data was gathered in February of 2000.

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pella
"Index of /srtm/version2_1/SRTM30"

[http://dds.cr.usgs.gov/srtm/version2_1/SRTM30/](http://dds.cr.usgs.gov/srtm/version2_1/SRTM30/)

[ [http://www2.jpl.nasa.gov/srtm/](http://www2.jpl.nasa.gov/srtm/) ]

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jcr83
This is the 30" version, not the 1" one !

