GeoNames Home | Postal Codes | Download / Webservice | About 

GeoNames Forum
  [Search] Search   [Recent Topics] Recent Topics   [Groups] Back to home page 
[Register] Register / 
[Login] Login 
api.geonames.org/srtm3? incorrect values for coordinates with elevations below MSL  XML
Forum Index -> General
Author Message
jooppeek



Joined: 09/04/2010 08:09:20
Messages: 8
Offline

Hello Marc,
It seems that srtm3 does not return correct values for coordinates which have elevations below MSL. E.g. Lelystad Airport in the Netherlands(http://ws.geonames.org/srtm3XML?lat=52.46&lng=5.53) returns 251, but should be approx. -4m (-13feet)
Could you please reply what is wrong, or what I'm doing wrong.
Thank you very much,
Joop
marc



Joined: 08/12/2005 07:39:47
Messages: 4412
Offline

Hi Joop

This seems to be wrong indeed. I don't know what is wrong, it could be that the srtm data production process has issues with this area.

Best Regards

Marc

[WWW]
jooppeek



Joined: 09/04/2010 08:09:20
Messages: 8
Offline

Hello Marc,
It is still not working for below MSL coordinates. Is there anyone you or I could address?
Best regards,
Joop
marc



Joined: 08/12/2005 07:39:47
Messages: 4412
Offline

Well, there is no fast solution. The data is from NASA with improvements made by CGIAR:
http://geonames.wordpress.com/2012/02/20/improved-srtm-digital-elevation-data/

Building new satellites, sending them to orbit etc will take some time ...


Best Regards

Marc

[WWW]
jooppeek



Joined: 09/04/2010 08:09:20
Messages: 8
Offline

Hello Marc,
I cannot open the link you posted.

It's strange that the service now returns incorrect below MSL altitudes, because I used it quite extensively a couple of years ago (2009/2010) and then it worked perfectly.

Well, I'm using it not very extensively for the Netherlands anymore, so I'll survive
Thanks for your effort and replies.

Regards,
Joop
jooppeek



Joined: 09/04/2010 08:09:20
Messages: 8
Offline

Hello Marc,
In previous mail I said that your link wasn't working. Disregard this remark. There was something wrong with my internet connection, and the link is ok.
Regards,
Joop
marc



Joined: 08/12/2005 07:39:47
Messages: 4412
Offline

You are right. The previous srtm data version has negative elevation at this position

http://api.geonames.org/srtm3XML?lat=52.46&lng=5.53&source=srtm3&username=demo

It looks like an error in the improved version.

Best Regards

Marc

[WWW]
marc



Joined: 08/12/2005 07:39:47
Messages: 4412
Offline

Update:

It turned out to be an error in the processing of the raw data. The error has been fixed, the data reprocessed and redeployed to all servers.

Best Regards

Marc

[WWW]
 
Forum Index -> General
Go to:   
Powered by JForum 2.1.5 © JForum Team