Add CRS to geojson output

[brunosan]

Add the CRS info to the geojson output.

Currently the workaround is this:

mercantile shapes - --x-json-seq  --mercator | \
sed -E 's/\}$/,"crs": \{"type": "EPSG","properties": \{"code": 3857 \}\}\}/g'

cc @hrwgc

[sgillies]

Is there a need for CRS? According to the last paragraph under "DESCRIPTION" in http://www.gdal.org/gdalwarp.html a Mercator GeoJSON with no CRS should be fine when the warp destination is Mercator.

The GeoJSON authors are recommending against the old GeoJSON objects in the latest draft submitted to the IETF: http://tools.ietf.org/html/draft-butler-geojson-04. I'm uncomfortable with having mercantile write the old style CRS objects.

[hrwgc]

@sgillies without CRS, gdalwarp assumes geojson cut line to be in WGS84, it appears from our testing yesterday.

Sent from my iPhone

On Aug 21, 2014, at 9:13 AM, Sean Gillies notifications@github.com wrote:

Is there a need for CRS? According to the last paragraph under "DESCRIPTION" in http://www.gdal.org/gdalwarp.html a Mercator GeoJSON with no CRS should be fine when the warp destination is Mercator.

The GeoJSON authors are recommending against the old GeoJSON objects in the latest draft submitted to the IETF: http://tools.ietf.org/html/draft-butler-geojson-04. I'm uncomfortable with having mercantile write the old style CRS objects.

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[sgillies]

Dammit, gdalwarp. I'm looking into it now. Meanwhile, here's the workaround using ogr2ogr to make an EPSG:3857 shapefile.

$ mercantile shapes "[106, 193, 9]" --mercator | ogr2ogr -f "ESRI Shapefile" -a_srs EPSG:3857 /tmp/mersh.shp /vsistdin/

I should update Fiona's fio script to allow the same kind of thing.

[sgillies]

See #16 (comment). Right now the workaround is to pipe CRS-less GeoJSON through ogr2ogr using /vsistdin/ and /vsistdout/.

mercantile shapes "[72, 109, 8]" --mercator \
| ogr2ogr /vsistdout/ /vsistdin/ -f GeoJSON -a_srs EPSG:3857 \
| gdalwarp ~/code/rasterio/rasterio/tests/data/RGB.byte.tif /tmp/72_109_8.tif -crop_to_cutline -cutline /vsistdin/ -t_srs EPSG:3857

[sgillies]

Fixed in Mercator 0.4 (coming soon). See #16 (comment)