[OSM-talk] "scale" a ShapeFile in Y-direction?

Mon May 11 22:32:14 BST 2009

Hi. Your file world_boundaries_m.shp seems to be in the old-fashioned EPSG:3395 we discussed a few days ago.

This should produce the shapefile you are looking for (world_boundaries_900913.shp):

ogr2ogr -f "ESRI Shapefile" -s_srs epsg:3395 -t_srs "+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 +over" world_boundaries_900913.shp world_boundaries_m.shp

regards
Juan Lucas

________________________________

		Hello,

		thanks for taking a look at it.  The output is ~ 19000 lines, so i'll just
		show the top ~70 lines:

		Had to open data source read-only.
		INFO: Open of `world_boundaries_m.shp'
		      using driver `ESRI Shapefile' successful.

		Layer name: world_boundaries_m
		Geometry: Polygon
		Feature Count: 3807
		Extent: (-20037400.000000, -19929239.110000) - (20037400.000000,
		18375854.709643)
		Layer SRS WKT:
		PROJCS["Mercator",
		    GEOGCS["GCS_WGS_1984",
		        DATUM["WGS_1984",
		            SPHEROID["WGS_1984",6378137,298.257223563]],
		        PRIMEM["Greenwich",0],
		        UNIT["Degree",0.017453292519943295]],
		    PROJECTION["Mercator_1SP"],
		    PARAMETER["latitude_of_origin",0],
		    PARAMETER["central_meridian",0],
		    PARAMETER["scale_factor",1],
		    PARAMETER["false_easting",0],
		    PARAMETER["false_northing",0],
		    UNIT["Meter",1]]
		CAT: Real (16.0)
		FIPS_CNTRY: String (80.0)
		CNTRY_NAME: String (80.0)
		OGRFeature(world_boundaries_m):0
		  CAT (Real) =               15
		  FIPS_CNTRY (String) = AY
		  CNTRY_NAME (String) = Antarctica

		OGRFeature(world_boundaries_m):1
		  CAT (Real) =               15
		  FIPS_CNTRY (String) = AY
		  CNTRY_NAME (String) = Antarctica

		OGRFeature(world_boundaries_m):2
		  CAT (Real) =               15
		  FIPS_CNTRY (String) = AY
		  CNTRY_NAME (String) = Antarctica

		OGRFeature(world_boundaries_m):3
		  CAT (Real) =               15
		  FIPS_CNTRY (String) = AY
		  CNTRY_NAME (String) = Antarctica

		OGRFeature(world_boundaries_m):4
		  CAT (Real) =               15
		  FIPS_CNTRY (String) = AY
		  CNTRY_NAME (String) = Antarctica

		OGRFeature(world_boundaries_m):5
		  CAT (Real) =               15
		  FIPS_CNTRY (String) = AY
		  CNTRY_NAME (String) = Antarctica

		OGRFeature(world_boundaries_m):6
		  CAT (Real) =              174
		  FIPS_CNTRY (String) = NZ
		  CNTRY_NAME (String) = New Zealand

		OGRFeature(world_boundaries_m):7
		  CAT (Real) =              174
		  FIPS_CNTRY (String) = NZ
		  CNTRY_NAME (String) = New Zealand

		OGRFeature(world_boundaries_m):8
		  CAT (Real) =              174
		  FIPS_CNTRY (String) = NZ
		  CNTRY_NAME (String) = New Zealand

		It additionally tells me on stderr:
		ERROR 4: Unable to open world_boundaries_m.shp or world_boundaries_m.SHP.

		Thanks for any hints,
		Torsten.

		Am Montag, 11. Mai 2009 12:42:44 schrieb Juan Lucas Dominguez Rubio:
		> Hi:
		>
		> I'm curious about that shapefile that needs some stretching. Assuming its
		> name is filename.shp, try to type this:
		>
		> ogrinfo -geom=NO filename.shp filename
		>
		> what is the output?
		>
		> Regards,
		> Juan Lucas
		>
		>
		> ________________________________
		>
		>
		>
		>
		>               Hello Frederik,
		>
		>               thanks for your hint. Yes, i know about projections.  Actually, i
		> reprojected the rester images of "blue marble" from a form of WGS84 to
		> Mercaator with an own program.
		>
		>               But as i've heard it, world_boundaries_m is "defect".  But as an overlay
		>               to represent the boundaries it would be ok.  If that information was a
		>               misunderstanding and could be fixed with the right projection that would
		> be awesome.
		>
		>               If i use shoreline_300 instead, the projection is perfectly fine, but if
		> you try to render it _not_filled_ with a LineSymbolizer instead of a
		> PolygonSymbolizer, you get some disturbing "plates".  But the projection is
		> fine.
		>
		>               A ShapeFile contains the "source SRS" inside it, right?  When rendering
		>               world_boundaries_m and shoreline_300 i used the same "target SRS".
		>               But the result leads to different positions on the final map.
		>
		>               Does that mean that world_boundaries_m is defect?
		>
		>               Is there a way to "fix" it somehow?  Or would scaling be possible?
		>
		>
		>               Best regards,
		>               Torsten.
		>
		>               > Hi,
		>               >
		>               > Torsten Mohr wrote:
		>               > > I have a ShapeFile that seems to be incorrect, scaling it in
		>               > > Y-direction could make it fit the background.
		>               >
		>               > Do you have a basic understanding of coordinate projections? If not,
		>               > you'd be well advised to spend a few hours reading on the subject
		>               > (start with Wikipedia, take it from there).
		>               >
		>               > You need to find out which projection your shapefile is in, and then
		>               > set the correct one in your map file, and things are likely to work.
		>               > Simply stretching the data from the shapefile is very unlikely to yield
		>               > the desired results - you will probably find that the stretch factor
		>               > that makes Iceland and the Equator fit will still have France out of
		>               > place.
		>               >
		>               > Bye
		>               > Frederik
		>
		>               _______________________________________________
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		>               talk at openstreetmap.org
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