Georeference/projection of .map file format (GDAL/OGR)

[alex81]

Hello,
I am trying to process a WAsP .map vector file (elevation or roughness file) with GDAL/OGR using the Python bindings. The import itself works, and I have access to all layer/features/fields. But what is missing, is the spatial reference of the layer (the OGR method GetSpatialRef() returns None).


Looking at the header of the .map file, it seems that the available projection information cannot be processed by the OGR driver:


+File1.map, UTM ED50: 30
0.0 1.0 0.0 1.0
1.0 0.0 1.0 0.0
1.0 0.0
0.0486 0.0005 4
493311.25 4734138.94
...


My question is: Does the first line of the header string follow any formatting standard (It is not PROJ4 format)? The string format seems to change from file to file, as seen here for 4 additional files:


+File2.map, 3: 30: 10: 0, UTM (north)-WGS84 Zone: 30, optimized
+File3.map, 5: : 13, British TM-OSGB36/Airy (GB/IE)
+File4.map, 3: 35: 2, UTM (north)-ED50 (Europe) Zone: 35, optimized | | WME v.10.1.0.320
+File5.map, 60: 34: 10: 0, UTM (south)-WGS84 Zone: 34, optimized


The information blocks seem to be comma-separated, with the 2nd block containing a tuple of 4 indices (a:b:c:d), which might stand for a coodinate system description (but it does not always appear, see File1.map). Are the tables describing these indices available?

The WAsP user manual does not provide any additional info on the first header line, unfortunately.


Thank you for your help.

Alex

[Niels Gylling Mortensen]

Dear Alex,
Hmm, I don't know exactly what format and rules are applied in the first line of the map file. I will forward your questions to the programmer of the feature.

Best regards,
Niels
WAsP Support

[Ole Rathmann]

Dear Alex,
I can give you an answer re. the Geo-referencing format used by the WAsP applications: WAsP Map Editor and WAsP itself. Your examples File2.map .. File5.map have apparently not been produced by these applications.

When saved by the Map Editor the header-line looks like this:
+Waspdale10 - webs-test | UTM-N Z31 WGS-8|WME ver. 11.22.1.29
So here "block2", between the first and the second bar-character, contains the projection specification: the projection type, the zone specification (if a zone is needed) and the datum-specifcation; here WGS-8 is the code for "WGS 84".
Block 3 has nothing to do with the geo-reference: it specifies the version of the Map Editor that produced the map file.

When exported by WAsP itself the header-line looks like this (one long line):
+ 'Canela' (WAsP export) 'Canela Terrain' | UTM-S Zone 19 (WGS 1984 datum)

Again, block 2 specifies the projection; the datum is here specified in parenthesis after the zone specification.

Hope this explanation is helpful.