Opened 8 years ago

Closed 8 years ago

Last modified 8 years ago

#12188 closed defect (fixed)

ProjectionRegressionTest failure after [9106]

Reported by: bastiK Owned by: team
Priority: normal Milestone: 15.12
Component: Core Version:
Keywords: Cc:

Description (last modified by bastiK)

After [9106], there is a considereable change for the projections "NAD27(76) / MTM" and "Monte Mario / Italy" with offsets of up to several hundred meters: test report

The reason for this is a missing datum in the definition and how this is handled by JOSM. Before r9106, we would implicitly add +towgs84=0,0,0, now we add +nadgrids=null. The first means that the ellipsoids are converted, but it is assumed they have the same center and orientation. The second skips datum conversion entirely and "casts" the lat/lon value.

I've changed this to mimic the behavior of the proj.4 software (unaware that we already have entries with unspecified datum).

Now is this change good or bad? I'm not sure, but I've tested toronto wms and it matches much better than before. Therefore, I keep it like this for now. If the previous version is preferred, it should be specified explicitly in the projection definition (add +towgs84=0,0,0).

Before (EPSG:2019):
(+proj=tmerc +lat_0=0 +lon_0=-79.5 +k=0.9999 +x_0=304800 +y_0=0 +ellps=clrk66 +units=m +bounds=-81.5,40,-77.5,60 +towgs84=0,0,0 +wmssrs=EPSG:2019)

(+proj=tmerc +lat_0=0 +lon_0=-79.5 +k=0.9999 +x_0=304800 +y_0=0 +ellps=clrk66 +units=m +bounds=-81.5,40,-77.5,60 +nadgrids=null +wmssrs=EPSG:2019)

Attachments (2)

toronto-towgs84.png (520.9 KB) - added by bastiK 8 years ago.
toronto-nadgrids.png (518.6 KB) - added by bastiK 8 years ago.

Download all attachments as: .zip

Change History (5)

Changed 8 years ago by bastiK

Attachment: toronto-towgs84.png added

Changed 8 years ago by bastiK

Attachment: toronto-nadgrids.png added

comment:1 Changed 8 years ago by bastiK

Description: modified (diff)

comment:2 Changed 8 years ago by bastiK

Resolution: fixed
Status: newclosed

In 9111/josm:

fixed #12188 - ProjectionRegressionTest failure after [9106]

comment:3 Changed 8 years ago by Don-vip

Milestone: 15.12

Modify Ticket

Change Properties
Set your email in Preferences
as closed The owner will remain team.
as The resolution will be set.
The resolution will be deleted.

Add Comment

E-mail address and name can be saved in the Preferences.

Note: See TracTickets for help on using tickets.