You can build a custom mercator projection centered approximately on the center of the swath. For example, use for swath 25: +proj=merc +lon_0=-140 +k=1 +x_0=0 +y_0=0 +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs In this projection, the swath is not broken by the dateline. You can create the polygon from the line. [![enter image description here][1]][1] Then create a cut polygon between -179.95°E and 179.9°E in EPSG:4326: Nr;WKT 1;POLYGON ((-179.95 89, 179.95 89, 179.95 -89, -179.95 -89, -179.95 89)) Reproject it to your custom CRS too, and subtract it from the swath polygon. After reprojecting back to EPSG:4326, the swath is correctly divided by the dateline: [![enter image description here][2]][2] Continue with all swaths that cross the dateline. [1]: https://i.sstatic.net/xfRQr.png [2]: https://i.sstatic.net/mY3El.png