#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 )
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)
Change History (37)
comment:1 Changed 12 years ago by
comment:2 Changed 12 years ago by
Cc: | sbrunner added |
---|
comment:3 Changed 12 years ago by
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 Changed 12 years ago by
@sbrunner: Do you like to pursue this? I haven't found any documentation on the low-level format of the binary file.
comment:5 Changed 12 years ago by
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 Changed 12 years ago by
Ok, if you are able to decipher the binary format, let me know!
Sebastian
comment:8 Changed 10 years ago by
Description: | modified (diff) |
---|---|
Keywords: | swiss unit test added |
comment:9 Changed 6 years ago by
There is now a free official Java library on Swisstopo website: https://shop.swisstopo.admin.ch/fr/products/geo_software/DLL_info
Changed 6 years ago by
Attachment: | reframeLib.jar added |
---|
Changed 6 years ago by
Attachment: | developper_manual.pdf added |
---|
Changed 6 years ago by
Attachment: | reframe.patch added |
---|
comment:10 Changed 6 years ago by
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 Changed 6 years ago by
I think you should convert to military LV03 (EPSG:21781) and not the civil which is no longer in use.
comment:12 Changed 6 years ago by
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 Changed 6 years ago by
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 Changed 6 years ago by
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 Changed 6 years ago by
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:17 Changed 6 years ago by
Keywords: | ntv2 grid added |
---|---|
Milestone: | → 17.04 |
Priority: | minor → normal |
OK. I will first try to implement this system with existing NTV2 grids through #14422 before adding the Swiss grid.
comment:19 Changed 6 years ago by
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 Changed 6 years ago by
Cc: | sebastic added |
---|
comment:21 follow-up: 22 Changed 6 years ago by
Aren't they already? What is missing from proj.4 is the German BETA2007.gsb.
comment:22 follow-up: 25 Changed 6 years ago by
comment:24 Changed 6 years ago by
Milestone: | 17.04 → 17.03 |
---|
#14422 was a lot easier than I thought :)
comment:25 Changed 6 years ago by
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:27 follow-up: 29 Changed 6 years ago by
ProjectionRefTest
needs an update but I cannot do it :(
comment:29 Changed 6 years ago by
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 Changed 6 years ago by
Resolution: | → fixed |
---|---|
Status: | new → closed |
Thanks! I tried but cs2cs
always replied "* *" and I didn't understand why.
comment:31 Changed 6 years ago by
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 follow-up: 33 Changed 6 years ago by
Maybe works now with changes from [11661] (try again next time...).
see also #5327