[gdal-dev] Trouble reprojecting feature that crosses antimeridian
Robin Wilson
robin at rtwilson.com
Tue Mar 29 13:30:19 PDT 2022
Hi,
I’ve been running into problems creating STAC items for images that cross the antimeridian. The geometries for the images are coming out as spanning the width of the whole world (from -180 to +180 degrees). With the help of the author of the tool I was using to create the STAC items (rio-stac), I’ve narrowed it down to a simple test case of reprojecting geometries (which is what the tool is doing internally).
If you put the following GeoJSON for an antimeridian-crossing polygon in WGS 84 / UTM zone 1N in a file called test_32601.geojson:
```
{"type":"Polygon","coordinates":[[[377120,7577600],[418080,7577600],[418080,7618560],[377120,7618560],[377120,7577600]]]}
```
and then run the following:
```
ogr2ogr -f GeoJSON -s_srs epsg:32601 -t_srs epsg:4326 out_4326.geojson test_32601.geojson
```
The contents of the output file will be:
```
{ "type": "Polygon", "coordinates": [ [ [ -179.018099960087909, 68.666857319910392 ], [ -178.985579869598382, 68.299719485120988 ], [ -179.976982644969041, 68.284942315413858 ], [ 179.974309855567753, 68.651801088224246 ], [ 180.0, 68.652259945574556 ], [ 180.0, 68.652259945541758 ], [ 180.0, 68.652259944541754 ], [ -180.0, 68.652259944541754 ], [ -180.0, 68.652259945541758 ], [ -180.0, 68.652259945610126 ], [ -179.018099960087909, 68.666857319910392 ] ] ] }
```
In that output geometry there are longitudes of 180 and -180, so when plotted on a map it spans the whole width of the world.
The author of the rio-stac library did a PR to try and fix this problem (https://github.com/developmentseed/rio-stac/pull/30), but it doesn’t seem to have fixed it for this example, as the underlying GDAL code used by his library (through rasterio, I believe) is giving this result.
I find this result unexpected, but I have no knowledge of how GDAL deals with the antimeridian. Is this to be expected, or is this potentially a bug? If it isn’t a bug, is there any way around this?
Best regards,
Robin
Dr Robin Wilson
www.rtwilson.com
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