20 km shift with SRID 32188

[kaligrafy]

Hi!

I tried to convert a lat/lon geographic geometry to MTM8 (SRID 32188) and I get a 20km shift (almost 20000 meters too high) for the y, but the x is correct.

If I use directly the postgis function ST_Transform, there is no shift.

Here is the rgeo command I use to transform (the one that shifts 20km):
RGeo::Feature.cast(geometry_attribute, :factory => RGeo::Cartesian.factory(:srs_database => RGeo::CoordSys::SRSDatabase::ActiveRecordTable.new, :srid => 32188), :project => true)

Thanks for any cue!

[kaligrafy]

I think the problem comes from the projection. If I project srid 4326 on itself:

RGeo::Feature.cast(geometry_attribute, :factory => RGeo::Cartesian.factory(:srs_database => RGeo::CoordSys::SRSDatabase::ActiveRecordTable.new, :srid => 4326), :project => true)

I get the same shift (0.2 degrees north)

Is it possible that there is a bug that first projects the geographic (that should not happen) and than project to geometry? Or maybe the factory isn't right...

[kaligrafy]

For testing:

SELECT ST_AsText(ST_Transform(ST_GeomFromText('POINT(-73.700666 45.528719)',4326), 32188))
RESULT => POINT(289125.877396516 5043219.80782975)

wgs84_factory = RGeo::Geographic.spherical_factory(:srid => 4326)
RGeo::Feature.cast(wgs84_factory.point(-73.700666, 45.528719), :factory => RGeo::Cartesian.factory(:srs_database => RGeo::CoordSys::SRSDatabase::ActiveRecordTable.new, :srid => 32188), :project => true)
RESULT => RGeo::Geos::CAPIPointImpl:0x3ff7fea7bcb0 "POINT (289179.3064137901 5064562.79613934)"

There is also a small shift with x. But the y shift is huge!!!
Comparison:
X: 289179 vs 289126
Y: 5064563 vs 5043220 (that's 21 km!!!)

[patrickespake]

+1
I have the same problem.

Any solution?

[ddd1600]

You do things a different way than I do, but if I wanted to convert geographic coordinates into (what are presumably) geometric coordinates, I'd do this:

lat, lng = -73.700666, 45.528719
srid = new_crs_srid = 32188
proj4 = new_crs_proj4 = "+proj=tmerc +lat_0=0 +lon_0=-73.5 +k=0.9999 +x_0=304800 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs " ##obtained from spatialreference.org
f = new_crs_factory = RGeo::Geographic.projected_factory(:projection_proj4 => proj4, :projection_srid => srid)
geom_shape_32188 = f.parse_wkt("POINT (#{lng} #{lat})").projection
#=> #<RGeo::Geos::CAPIPointImpl:0x3fe49ee7c404 "POINT (289125.8773965159 5043219.807829753)"> 

Is that correct now? (checking, yes, it is. hehe you're welcome)

[patrickespake]

I tried it, but don't work for me:

[5] pry(main)> geom_shape_32188 = f.parse_wkt("POINT (#{lng} #{lat})").projection
ArgumentError: wrong number of arguments (0 for 2+)
from /Users/patrickespake/.rvm/gems/ruby-2.1.1@quality-maps/gems/rgeo-0.3.20/lib/rgeo/geos/capi_factory.rb:352:in `point'

[kaligrafy]

lat and lon are reversed...

[keithdoggett]

I tried @ddd1600's solution (while flipping lat/lon) and it worked. This issue is very old and a lot has changed in the library since then, so I'm going to close but if this still isnt' working, please open a new issue.