Reproject: Enhance performance of multiple reprojections.

geofurlong · Jun 8, 2024 · cc7a32e · cc7a32e
1 parent eaff1cb
commit cc7a32e
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Showing 3 changed files with 8 additions and 9 deletions.
diff --git a/cmd/builder/precompute.go b/cmd/builder/precompute.go
@@ -24,7 +24,7 @@ func precompute(cfg GeofurlongConfig, resolution int) { //
  geocode.Check(err)
 
  // Set up projection conversion from OSGB planar (EPSG:27700) to geographic longitude / latitude (EPSG:4326).
- pj := geocode.OSGBtoLongLat()
+ pj := geocode.OSGBToLonLat()
 
  file, err := os.Create(fmt.Sprintf("%s/geofurlong_precomputed_%.4dy.csv", cfg["precompute_dir"], resolution))
  geocode.Check(err)

diff --git a/pkg/geocode/reproject.go b/pkg/geocode/reproject.go
@@ -15,8 +15,8 @@ const (
  GeographicCRS = "EPSG:4326"
 )
 
-// OSGBtoLongLat returns a pointer to the transformer from projected OSGB36 (EPSG:27700) to geographic Longitude / Latitude (EPSG:4326).
-func OSGBtoLongLat() *proj.PJ {
+// OSGBToLonLat returns a pointer to the transformer from projected OSGB36 (EPSG:27700) to geographic Longitude / Latitude (EPSG:4326).
+func OSGBToLonLat() *proj.PJ {
  pj, err := proj.NewCRSToCRS(ProjectedCRS, GeographicCRS, nil)
  Check(err)
 
@@ -33,10 +33,8 @@ func Reproject(point orb.Point, pj *proj.PJ) orb.Point {
 }
 
 // ReprojectMulti takes a slice of projected Easting / Northing points and returns the corresponding Longitude / Latitude points slice.
-func ReprojectMulti(points []orb.Point) []orb.Point {
+func ReprojectMulti(points []orb.Point, pj *proj.PJ) []orb.Point {
  latLons := make([]orb.Point, len(points))
- pj, err := proj.NewCRSToCRS(ProjectedCRS, GeographicCRS, nil)
- Check(err)
 
  for i, point := range points {
  latLon, err := pj.Forward(proj.Coord{point.X(), point.Y()})

diff --git a/pkg/geocode/reproject_test.go b/pkg/geocode/reproject_test.go
@@ -17,7 +17,7 @@ func TestReproject(t *testing.T) {
  planarPoints = append(planarPoints, orb.Point{float64(testPlace.easting), float64(testPlace.northing)})
  }
 
- geoPoints := ReprojectMulti(planarPoints)
+ geoPoints := ReprojectMulti(planarPoints, OSGBToLonLat())
  for i, testPlace := range testPlaces {
  deltaX := geoPoints[i].Point().X() - testPlace.lonLat.X()
  deltaY := geoPoints[i].Point().Y() - testPlace.lonLat.Y()
@@ -28,9 +28,9 @@ func TestReproject(t *testing.T) {
  }
  }
 
- pj := OSGBtoLongLat()
+ pjToGeo := OSGBToLonLat()
  for _, testPlace := range testPlaces {
- geoPoint := Reproject(orb.Point{float64(testPlace.easting), float64(testPlace.northing)}, pj)
+ geoPoint := Reproject(orb.Point{float64(testPlace.easting), float64(testPlace.northing)}, pjToGeo)
  deltaX := geoPoint.X() - testPlace.lonLat.X()
  deltaY := geoPoint.Y() - testPlace.lonLat.Y()
 
@@ -39,4 +39,5 @@ func TestReproject(t *testing.T) {
  t.Fail()
  }
  }
+
 }