API REST Elevation: is 0.5m resolution available ?

[francois bourdon]

Hello,

I am using the API REST to get elevations (Height and Profile API REST Services — GeoAdmin API 3.0 documentation)

Seams to me the data resolution is 2m when I need the best swissALTI3D resolution of 0.5m, is there a way to get 0.5m resolution through the API REST ?

Thanks

Francois

[GeoAdminCh API]

Can you post the request where you got 2m?

 be aware

https://www.swisstopo.admin.ch/en/geodata/height/alti3d.html#technische_details

Quality

The information provided corresponds to the accuracies (1 sigma) of all three dimensions. The spatial distribution of these different kinds of data is available in the release note (available only in German or French).

New generation of LiDAR data : 0.3 m

Previous generation of LiDAR data (less than 2,000 metres above sea level): 0.5 m

Stereo correlation  (more than 2,000 metres above sea level): 1 to 3 m

Manual updates (individual points, breaklines and areas): 0.1 m to 1 m

[francois bourdon]

Thanks for your quick answer, you're right I should have sent  the request for clarity.

You can check the request below, one point every 0.5m but the altitude only change every 4 points, make me think the resolution is 2m

https://api3.geo.admin.ch/rest/services/profile.json?geom={%22type%22%3A%22LineString%22%2C%22coordinates%22%3A[[2677999.2194082%2C1213661.38728401]%2C[2677999.72644072%2C1213661.39391905]%2C[2678000.23347323%2C1213661.40055414]%2C[2678000.74050575%2C1213661.40718928]%2C[2678001.24753827%2C1213661.41382445]%2C[2678001.75457078%2C1213661.42045967]%2C[2678002.2616033%2C1213661.42709493]%2C[2678002.76863581%2C1213661.43373023]%2C[2678003.20323511%2C1213661.43941767]%2C[2678003.71026762%2C1213661.44605306]%2C[2678004.21730013%2C1213661.45268848]%2C[2678004.72433265%2C1213661.45932396]]}&sr=2056&nb_points=2

Thanks for your technical link (I have no problem reading french :-)

Francois

[francois bourdon]

Hello, any update ?

[GeoAdminCh API]

First : Sorry  for the late reply. message ended  up in spam

The answer  is simple; you need to tinker with "nb_points" http://api.geo.admin.ch/services/sdiservices.html#profile  parameter

https://api3.geo.admin.ch/rest/services/profile.json?geom={"type":"LineString","coordinates":[[2677999.2194082,1213661.38728401],[2677999.72644072,1213661.39391905],[2678000.23347323,1213661.40055414],[2678000.74050575,1213661.40718928],[2678001.24753827,1213661.41382445],[2678001.75457078,1213661.42045967],[2678002.2616033,1213661.42709493],[2678002.76863581,1213661.43373023],[2678003.20323511,1213661.43941767],[2678003.71026762,1213661.44605306],[2678004.21730013,1213661.45268848],[2678004.72433265,1213661.45932396]]}&sr=2056&nb_points=1000

[francois bourdon]

Thanks ! I have to try this solution

[francois bourdon]

Hi, 

unfortunately changing nb_points doesn't help in my case

For example, if you try a simple profile (two points, distance in between 10 meters) with nb_points=20, I would expect to see the altitude changing every point, but it only changes every 4 points (= every 2 meters...)

https://api3.geo.admin.ch/rest/services/profile.json?geom={%22type%22%3A%22LineString%22%2C%22coordinates%22%3A[[2564461%2C1103625]%2C[2564471%2C1103625]]}&sr=2056&nb_points=20

You can increase np_points to 200 or 1000, you have more points but altitude resolution remains 2 meters

I really feel the swissALTI3D database resolution is 2m and not 0.5m

Can you confirm and tell me if it is possible to have access to the 0.5m resolution data ?

Thanks!

François

[francois bourdon]

Hi, any update on this topic ? We have customers expecting 0.5m resolution (ALBERTI INGÉNIEURS SA, LOSINGER MARAZZI SA (LAUSANNE), HRS REAL ESTATE SA, GEOTEST, GRISONI, SB INGÉNIERIE SÀRL, INDUNI & CIE, BG INGÉNIEURS CONSEILS (VERNIER)) and I need to know if it is possible the way I use the API

Thanks !

[David...@swisstopo.ch]

Hi there

Now I see your point, altitude changes after 2m

 

I’ll ask internally--

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[David...@swisstopo.ch]

Confirmed

 

The data source behind the webservice is only 2m ( the use case so far was: get profile for hiking as used in swisstopo app, schweizmobile etc…)

We plan in the far future 202X  to provide a full res service… but this is only a “plan” so far

 

IF you really need the full res data: then you would need to download the  raw data via https://www.swisstopo.admin.ch/de/geodata/height/alti3d.html

 

Or via STAC API https://www.geo.admin.ch/stac-api for  ch.swisstopo.swissalti3d 

 

Sorry for that

 

David

 

 

Von: geoadm...@googlegroups.com <geoadm...@googlegroups.com> Im Auftrag von francois bourdon
Gesendet: Donnerstag, 28. Juli 2022 07:36
An: GeoAdminCh API <geoadm...@googlegroups.com>
Betreff: Re: API REST Elevation: is 0.5m resolution available ?

 

Hi, any update on this topic ? We have customers expecting 0.5m resolution (ALBERTI INGÉNIEURS SA, LOSINGER MARAZZI SA (LAUSANNE), HRS REAL ESTATE SA, GEOTEST, GRISONI, SB INGÉNIERIE SÀRL, INDUNI & CIE, BG INGÉNIEURS CONSEILS (VERNIER)) and I need to know if it is possible the way I use the API

--

[francois bourdon]

Thanks David for your response, it confirms what I suspected...

This is bad news for us because stac-api is really not convienient: I already use it for buildings and it is not at all designed for requests in a specific zone: you need to download one or more "big tiles" and filter big amount of data. Long download, processing and hence not at all efficient !

If you can forward this strong request to the relevant people it would be appreciated

Have a nice day !

Regards,

François

[David...@swisstopo.ch]

Hi François

 

Will forward this request

 

Furthermore: you propose the need for a national high res elevation service in http://geounconference.ch/ , add your request in https://github.com/GeoUnconference/discussions/discussions  and activate your network for upvotes /contribution

 

On short term:

-          ESRI https://www.esri.com/arcgis-blog/products/analytics/analytics/introducing-esris-world-elevation-services/  According to https://www.arcgis.com/home/item.html?id=3af669838f594b378f90c10f98e46a7f they have the 0.5m swissalti in their https://www.arcgis.com/home/item.html?id=58a541efc59545e6b7137f961d7de883 and they seem to have a profile service https://developers.arcgis.com/javascript/latest/api-reference/esri-widgets-ElevationProfile.html  , terms and costs: you have to dig through their site

 

 

Further elevation services, free non free with different spatial resolutions,  I’m aware of are

 

-          https://www.opentopodata.org/

-          https://developers.google.com/maps/documentation/elevation/start

-          https://github.com/Jorl17/open-elevation

-          https://documentation.maptiler.com/hc/en-us/articles/4405444518545-How-to-draw-elevation-profile-for-your-path

-          https://docs.microsoft.com/en-us/bingmaps/rest-services/elevations/?toc=https%3A%2F%2Fdocs.microsoft.com%2Fen-us%2Fbingmaps%2Frest-services%2Ftoc.json&bc=https%3A%2F%2Fdocs.microsoft.com%2Fen-us%2FBingMaps%2Fbreadcrumb%2Ftoc.json

 

Hope this helps

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[francois bourdon]

Wow ! Thanks a lot David, I will investigate

Yes it helps

François

[GeoAdminCh API]

just for the sake of completness :

https://www.gpxz.io/  nice sample along path https://www.gpxz.io/docs#elevation-sample ( only 2m in switzerland but might change in the future)