Opened 13 years ago
Closed 13 years ago
#4115 closed defect (fixed)
Conversion of "Popular Visualisation CRS" projection in MapInfo tab file is faulty
Reported by: | stevemargetts | Owned by: | warmerdam |
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Priority: | normal | Milestone: | 1.9.0 |
Component: | OGR_SRS | Version: | unspecified |
Severity: | normal | Keywords: | mitab Popular Visualisation CRS, MapInfo, Virtual Earth |
Cc: | Daniel Morissette |
Description
MapInfo 10.5 allows the user to draw polygons on top of background images provided by Virtual Earth. If you do this, the resulting polygons have the "Popular Visualisation CRS" projection (EPSG: 3857).
When read by OGR, this projection is not converted correctly, resulting in a significant shift in the polygons. It appears that the spheroid definition is not set correctly, as it ends up being set to SPHEROID["unknown",6378137,298.257223563], instead of SPHEROID["Popular Visualisation Sphere",6378137,0]
The attached file should display this issue
Attachments (2)
Change History (5)
by , 13 years ago
Attachment: | Problem regions.zip added |
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comment:1 by , 13 years ago
Cc: | added |
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Keywords: | mitab added |
Status: | new → assigned |
Steve,
It seems this file has spheroid 54 while the highest we have a definition for is 51, and it has datum 157 while the highest we have is 152. Do you happen to know of a datum and/or ellipse definition table we could use to extend the mapinfo driver code?
If it is convenient I would also be pleased to have the same file translated to mif format with mapinfo.
comment:2 by , 13 years ago
Thanks for the prompt response. I've uploaded a MIF export of the same data; the projection string is "CoordSys Earth Projection 10, 157, "m", 0 Bounds (-40075016.6856, -20037508.343) (40075016.6856, 20037508.343)"
I'm afraid don't know the datum definition, but my guess would be that it's a mercator projection based on a sphere, as used by Virtual Earth (i.e., a radius of 6378137m with no flattening).
If it helps, the corresponding proj4 projection string seems to be "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs"
comment:3 by , 13 years ago
Milestone: | → 1.9.0 |
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Resolution: | → fixed |
Status: | assigned → closed |
I have somewhat blindly implemented support for reading, but not writing google mercator based on these examples (r22524). Also upstreamed into mitab cvs.
MapInfo tab file showing the problem