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Opened 14 years ago

Closed 8 years ago

Last modified 7 years ago

#5399 closed defect (fixed)

Swissgrid CH1903 is off by up to 3 meters (does not use data set of local corrections )

Reported by: bastiK Owned by: team
Priority: normal Milestone: 17.03
Component: Core Version: latest
Keywords: projection swiss unit test ntv2 grid Cc: sbrunner, stoecker, simon04, wiktorn, Klumbumbus, sebastic

Description (last modified by Don-vip)

To calculate CH1903, 2 steps are required:

(1) WSG84 -> CH1903+ (using a formula)

(2) CH1903+ -> CH1903 (using a grid / triangulation file)

Step (1) if fully implemented. However step (2) is missing. It introduces corrections of up to 3 meters (plus false easting/northing of 2000000/1000000) and accounts for the historical deviations from the modern system.

To fix this, we could:

  • Use the "official" triangulation file and FINELTRA algorithm.
  • Use the NTv2 grid file provided by swisstopo. This is an approximation, but should be in general good enough for osm use.

Link:
http://www.swisstopo.admin.ch/internet/swisstopo/en/home/products/software/products/chenyx06.html

Attachments (4)

CHENyx06.bin.zip (319.8 KB ) - added by bastiK 14 years ago.
triagulation data (binary format)
reframeLib.jar (1.9 MB ) - added by Don-vip 8 years ago.
developper_manual.pdf (738.1 KB ) - added by Don-vip 8 years ago.
reframe.patch (4.7 KB ) - added by Don-vip 8 years ago.

Change History (37)

comment:1 by bastiK, 14 years ago

see also #5327

comment:2 by bastiK, 14 years ago

Cc: sbrunner added

by bastiK, 14 years ago

Attachment: CHENyx06.bin.zip added

triagulation data (binary format)

comment:3 by bastiK, 14 years ago

On the swisstopo website only NTv2 grid is available, but the link to the triangulation file is dead.

I sent an email to swisstopo and received the file in binary format. (The link is still not working.)

comment:4 by bastiK, 14 years ago

@sbrunner: Do you like to pursue this? I haven't found any documentation on the low-level format of the binary file.

comment:5 by sbrunner, 14 years ago

Hi,

Yes, I plan to see what is possible to do but not right now, (actually I'm working on better support of OSM file format in OpenLayers ;-) )

CU, Stéphane

comment:6 by bastiK, 14 years ago

Ok, if you are able to decipher the binary format, let me know!

Sebastian

comment:7 by Don-vip, 11 years ago

Ticket #8949 has been marked as a duplicate of this ticket.

comment:8 by Don-vip, 11 years ago

Description: modified (diff)
Keywords: swiss unit test added

comment:9 by Don-vip, 8 years ago

There is now a free official Java library on Swisstopo website: https://shop.swisstopo.admin.ch/fr/products/geo_software/DLL_info

by Don-vip, 8 years ago

Attachment: reframeLib.jar added

by Don-vip, 8 years ago

Attachment: developper_manual.pdf added

by Don-vip, 8 years ago

Attachment: reframe.patch added

comment:10 by Don-vip, 8 years ago

I started to play with the library (see attached jar, developer manual and not-working patch) but can't find the correct usage. bastiK can you please help me? :)

comment:11 by bastiK, 8 years ago

I think you should convert to military LV03 (EPSG:21781) and not the civil which is no longer in use.

comment:12 by bastiK, 8 years ago

They do have a download for the NTv2 grid file by now, so no extra code or library is needed. I couldn't find appropriate terms and on the current side, but this offer should still apply. This means The conditions are similar to those of the other grid files we distribute.

comment:13 by Don-vip, 8 years ago

Ah, even better. Do we need the two NTv2 grids or only one?

Concerning the license it seems OK, to be sure we can include it in the SVN as the URLs are not stable. Even if not strictly required, we can also apply the first licence for free geodata obligation:

To add a clearly visible source reference with the following wording whenever geodata are published or passed on: “Source: Swiss Federal Office of Topography” (Article 30, Geoinformation Ordinance);

comment:14 by bastiK, 8 years ago

The one labelled "NTv2 grid ETRF93/ETRS89 -> CH1903/LV95" should be enough to add full EPSG:21781 support. (I think CH1903/LV95 is a typo and they mean CH1903/LV03.)

It works with the cs2cs tools, so there should be no problem in JOSM:

$ echo "601000.0 197500.0 555.0" | cs2cs +proj=somerc +lat_0=46.95240555555556 +lon_0=7.439583333333333 +x_0=600000 +y_0=200000 +ellps=bessel +nadgrids=./CHENYX06_etrs.gsb +to +proj=lonlat +datum=WGS84
7d27'6.35"E	46d55'42.94"N 555.000

How do you plan to make the file available to the user as its 3 MB?

comment:15 by Don-vip, 8 years ago

Cc: stoecker simon04 wiktorn Klumbumbus added

Good question. I think it would be worth to implement a NTV2 file management as official JOSM extension. If the default JOSM jar does not contain the required NTV2 files, the first time a user chooses a projection that requires ones, the grid is downloaded from JOSM server and stored in JOSM cache directory.

We could also still build a bigger jar file containing all grids for users who need JOSM to remain fully operational without Internet access.

@team: what you do think?

comment:16 by stoecker, 8 years ago

Sounds like a good idea and makes the JAR smaller.

comment:17 by Don-vip, 8 years ago

Keywords: ntv2 grid added
Milestone: 17.04
Priority: minornormal

OK. I will first try to implement this system with existing NTV2 grids through #14422 before adding the Swiss grid.

Last edited 8 years ago by Don-vip (previous) (diff)

comment:18 by bastiK, 8 years ago

+1

comment:19 by Don-vip, 8 years ago

I have sent an e-mail to SwissTopo to ask them clarifications about the redistribution/licence. I hope the grids will then be included into proj.4 as well.

comment:20 by sebastic, 8 years ago

Cc: sebastic added

comment:21 by bastiK, 8 years ago

Aren't they already? What is missing from proj.4 is the German BETA2007.gsb.

in reply to:  21 ; comment:22 by Don-vip, 8 years ago

Replying to bastiK:

Aren't they already?

No, see here.

What is missing from proj.4 is the German BETA2007.gsb.

Can you please create a ticket or even a PR? I'm not familiar with this one ;)

comment:23 by sebastic, 8 years ago

The PROJ.4 documentation lists most common national grids, see:

http://proj4.org/grids.html

comment:24 by Don-vip, 8 years ago

Milestone: 17.0417.03

#14422 was a lot easier than I thought :)

in reply to:  22 comment:25 by bastiK, 8 years ago

Replying to Don-vip:

Replying to bastiK:

Aren't they already?

No, see here.

What is missing from proj.4 is the German BETA2007.gsb.

Okay, I falsely assumed the content of the proj-data Debian package is the same as what is in the proj.4 repository. Apparently the debian maintainer add the Swiss grid file when the package is built.

Can you please create a ticket or even a PR? I'm not familiar with this one ;)

I've sent an email to the contact person of the German agency to clarify the usage terms.

comment:26 by Don-vip, 8 years ago

In 11660/josm:

see #5399 - Swissgrid: add NTv2 grid file provided by swisstopo

comment:27 by Don-vip, 8 years ago

ProjectionRefTest needs an update but I cannot do it :(

comment:28 by bastiK, 8 years ago

In 11661/josm:

see #5399 - update ProjectionRefTest

in reply to:  27 comment:29 by bastiK, 8 years ago

Replying to Don-vip:

ProjectionRefTest needs an update but I cannot do it :(

I hoped others would be able to update it too ...

comment:30 by Don-vip, 8 years ago

Resolution: fixed
Status: newclosed

Thanks! I tried but cs2cs always replied "* *" and I didn't understand why.

comment:31 by Don-vip, 8 years ago

Summary: Swissgrild CH1903 is off by up to 3 meters (does not use data set of local corrections )Swissgrid CH1903 is off by up to 3 meters (does not use data set of local corrections )

comment:32 by bastiK, 8 years ago

Maybe works now with changes from [11661] (try again next time...).

in reply to:  32 comment:33 by Don-vip, 7 years ago

Replying to bastiK:

Maybe works now with changes from [11661] (try again next time...).

I tried again in order to add ESRI projections (#15880) and it works!

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