PDOK-14231

Als OZON wil ik uitgefilterde geometrieën geaggregeerd kunnen weergeven (POC)

go.mod

@@ -9,6 +9,8 @@ require (
 	github.com/urfave/cli/v2 v2.8.1
 )
 
+require github.com/twpayne/go-geom v1.4.1
+
 require (
 	github.com/gdey/errors v0.0.0-20190426172550-8ebd5bc891fb // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect

go.sum

@@ -1,34 +1,91 @@
+github.com/Azure/go-ansiterm v0.0.0-20170929234023-d6e3b3328b78/go.mod h1:LmzpDX56iTiv29bbRTIsUNlaFfuhWRQBWjQdVyAevI8=
+github.com/DATA-DOG/go-sqlmock v1.3.2/go.mod h1:f/Ixk793poVmq4qj/V1dPUg2JEAKC73Q5eFN3EC/SaM=
+github.com/Masterminds/goutils v1.1.0/go.mod h1:8cTjp+g8YejhMuvIA5y2vz3BpJxksy863GQaJW2MFNU=
+github.com/Masterminds/semver v1.5.0/go.mod h1:MB6lktGJrhw8PrUyiEoblNEGEQ+RzHPF078ddwwvV3Y=
+github.com/Masterminds/sprig v2.22.0+incompatible/go.mod h1:y6hNFY5UBTIWBxnzTeuNhlNS5hqE0NB0E6fgfo2Br3o=
+github.com/Microsoft/go-winio v0.4.14/go.mod h1:qXqCSQ3Xa7+6tgxaGTIe4Kpcdsi+P8jBhyzoq1bpyYA=
+github.com/Nvveen/Gotty v0.0.0-20120604004816-cd527374f1e5/go.mod h1:lmUJ/7eu/Q8D7ML55dXQrVaamCz2vxCfdQBasLZfHKk=
 github.com/arolek/p v0.0.0-20191103215535-df3c295ed582/go.mod h1:JPNItmi3yb44Q5QWM+Kh5n9oeRhfcJzPNS90mbLo25U=
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+github.com/mitchellh/copystructure v1.0.0/go.mod h1:SNtv71yrdKgLRyLFxmLdkAbkKEFWgYaq1OVrnRcwhnw=
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+github.com/opencontainers/runc v1.0.0-rc9/go.mod h1:qT5XzbpPznkRYVz/mWwUaVBUv2rmF59PVA73FjuZG0U=
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 github.com/pborman/uuid v1.2.0/go.mod h1:X/NO0urCmaxf9VXbdlT7C2Yzkj2IKimNn4k+gtPdI/k=
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 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
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+github.com/twpayne/go-polyline v1.0.0/go.mod h1:ICh24bcLYBX8CknfvNPKqoTbe+eg+MX1NPyJmSBo7pU=
+github.com/twpayne/go-waypoint v0.0.0-20200706203930-b263a7f6e4e8/go.mod h1:qj5pHncxKhu9gxtZEYWypA/z097sxhFlbTyOyt9gcnU=
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 github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673/go.mod h1:N3UwUGtsrSj3ccvlPHLoLsHnpR27oXr4ZE984MbSER8=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
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 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
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 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
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+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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+gopkg.in/yaml.v2 v2.2.7/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
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pkg/gpkg/gpkg.go

@@ -28,6 +28,10 @@ func (f *featureGPKG) UpdateGeometry(geometry geom.Geometry) {
 	f.geometry = geometry
 }
 
+func (f *featureGPKG) IsReduced(isReduced bool) {
+	f.columns = append(f.columns, isReduced)
+}
+
 type column struct {
 	cid       int
 	name      string
@@ -323,6 +327,10 @@ func (t Table) selectSQL() string {
 // build the INSERT statement based on the table and columns
 func (t Table) insertSQL() string {
 	var csql, vsql []string
+	t.columns = append(t.columns, column{
+		name:  "isReduced",
+		ctype: "BOOLEAN",
+	})
 	for _, c := range t.columns {
 		if c.name != t.gcolumn {
 			csql = append(csql, c.name)
@@ -374,6 +382,10 @@ func getTableColumns(h *gpkg.Handle, table string) []column {
 
 // buildTable creates a given destination table with the necessary gpkg_ information
 func buildTable(h *gpkg.Handle, t Table) error {
+	t.columns = append(t.columns, column{
+		name:  "isReduced",
+		ctype: "BOOLEAN",
+	})
 	query := t.createSQL()
 	_, err := h.Exec(query)
 	if err != nil {
@@ -385,8 +397,9 @@ func buildTable(h *gpkg.Handle, t Table) error {
 		ShortName:     t.Name,
 		Description:   t.Name,
 		GeometryField: t.gcolumn,
-		GeometryType:  t.gtype,
-		SRS:           int32(t.srs.ID),
+		// as sieved geometry is reduced to a POINT, it is necessary to allow multiple geometry types
+		GeometryType: gpkg.Geometry,
+		SRS:          int32(t.srs.ID),
 		//
 		Z: gpkg.Prohibited,
 		M: gpkg.Prohibited,

pkg/interface.go

@@ -6,6 +6,7 @@ type Feature interface {
 	Columns() []interface{}
 	Geometry() geom.Geometry
 	UpdateGeometry(geom.Geometry)
+	IsReduced(bool)
 }
 
 type Source interface {

pkg/sieve.go

@@ -1,6 +1,8 @@
 package pkg
 
 import (
+	geometry "github.com/twpayne/go-geom"
+	"github.com/twpayne/go-geom/xy"
 	"log"
 	"math"
 
@@ -27,25 +29,28 @@ func sieveFeatures(preSieve chan Feature, postSieve chan Feature, resolution flo
 			preSieveCount++
 			switch feature.Geometry().(type) {
 			case geom.Polygon:
-				var p geom.Polygon
-				p = feature.Geometry().(geom.Polygon)
-				if p := polygonSieve(p, resolution); p != nil {
-					feature.UpdateGeometry(p)
+				p := feature.Geometry().(geom.Polygon)
+				sievedPolygon, isReduced := polygonSieve(p, resolution)
+				feature.UpdateGeometry(sievedPolygon)
+				feature.IsReduced(isReduced)
+				if !isReduced {
 					postSieveCount++
-					postSieve <- feature
 				}
+				postSieve <- feature
 			case geom.MultiPolygon:
-				var mp geom.MultiPolygon
-				mp = feature.Geometry().(geom.MultiPolygon)
-				if mp := multiPolygonSieve(mp, resolution); mp != nil {
-					feature.UpdateGeometry(mp)
-					multiPolygonCount++
+				mp := feature.Geometry().(geom.MultiPolygon)
+				mp, isReduced := multiPolygonSieve(mp, resolution)
+				feature.UpdateGeometry(mp)
+				feature.IsReduced(isReduced)
+				multiPolygonCount++
+				if !isReduced {
 					postSieveCount++
-					postSieve <- feature
 				}
+				postSieve <- feature
 			default:
 				postSieveCount++
 				nonPolygonCount++
+				feature.IsReduced(false)
 				postSieve <- feature
 			}
 		}
@@ -57,7 +62,7 @@ func sieveFeatures(preSieve chan Feature, postSieve chan Feature, resolution flo
 	if preSieveCount != nonPolygonCount {
 		log.Printf("     multipolygons: %d", multiPolygonCount)
 	}
-	log.Printf("              kept: %d", postSieveCount)
+	log.Printf("       not reduced: %d", postSieveCount)
 }
 
 // writeFeatures collects the processed features by the sieveFeatures and
@@ -69,19 +74,54 @@ func writeFeaturesToTarget(postSieve chan Feature, kill chan bool, target Target
 	kill <- true
 }
 
+// getMultiPolygonCentroid returns Point with the centroid value of a multiPolygon
+func getMultiPolygonCentroid(mp geom.MultiPolygon) geom.Point {
+	var multiPolygonCoords [][][]geometry.Coord
+	for _, p := range mp {
+		multiPolygonCoords = append(multiPolygonCoords, getPolygonCoords(p))
+	}
+	if len(multiPolygonCoords) != 0 {
+		centroidCoord, err := xy.Centroid(geometry.NewMultiPolygon(geometry.XY).MustSetCoords(multiPolygonCoords))
+		if err != nil {
+			panic(err)
+		}
+		return [2]float64{centroidCoord[0], centroidCoord[1]}
+	} else {
+		return [2]float64{0, 0}
+	}
+}
+
+// getPolygonCentroid returns Point with the centroid value of a polygon
+func getPolygonCentroid(p geom.Polygon) geom.Point {
+	polygonCoords := getPolygonCoords(p)
+	if polygonCoords != nil {
+		centroidCoord, err := xy.Centroid(geometry.NewPolygon(geometry.XY).MustSetCoords(polygonCoords))
+		if err != nil {
+			panic(err)
+		}
+		return [2]float64{centroidCoord[0], centroidCoord[1]}
+	} else {
+		return [2]float64{0, 0}
+	}
+}
+
 // multiPolygonSieve will split it self into the separated polygons that will be sieved before building a new MULTIPOLYGON
-func multiPolygonSieve(mp geom.MultiPolygon, resolution float64) geom.MultiPolygon {
+func multiPolygonSieve(mp geom.MultiPolygon, resolution float64) (geom.MultiPolygon, bool) {
 	var sievedMultiPolygon geom.MultiPolygon
+	var isReduced bool
 	for _, p := range mp {
-		if sievedPolygon := polygonSieve(p, resolution); sievedPolygon != nil {
+		if sievedPolygon, b := polygonSieve(p, resolution); b == false {
 			sievedMultiPolygon = append(sievedMultiPolygon, sievedPolygon)
+		} else {
+			isReduced = true
+			sievedMultiPolygon = append(sievedMultiPolygon, [][][2]float64{{getPolygonCentroid(p)}})
 		}
 	}
-	return sievedMultiPolygon
+	return sievedMultiPolygon, isReduced
 }
 
 // polygonSieve will sieve a given POLYGON
-func polygonSieve(p geom.Polygon, resolution float64) geom.Polygon {
+func polygonSieve(p geom.Polygon, resolution float64) (geom.Polygon, bool) {
 	minArea := resolution * resolution
 	if area(p) > minArea {
 		if len(p) > 1 {
@@ -92,11 +132,15 @@ func polygonSieve(p geom.Polygon, resolution float64) geom.Polygon {
 					sievedPolygon = append(sievedPolygon, interior)
 				}
 			}
-			return sievedPolygon
+			return sievedPolygon, false
 		}
-		return p
+		return p, false
+	}
+	if p == nil {
+		return nil, false
+	} else {
+		return [][][2]float64{{getPolygonCentroid(p)}}, true
 	}
-	return nil
 }
 
 // calculate the area of a polygon
@@ -145,3 +189,24 @@ func Sieve(source Source, target Target, resolution float64) {
 	}
 	close(kill)
 }
+
+func getPolygonCoords(p geom.Polygon) [][]geometry.Coord {
+	var multiXyCoordinates [][]geometry.Coord
+	if p == nil {
+		return nil
+	}
+	for _, polygon := range p {
+		var xyCoordinates []geometry.Coord
+		if len(polygon) != 0 {
+			for _, point := range polygon {
+				xyCoordinates = append(xyCoordinates, makeCoord(point))
+			}
+			multiXyCoordinates = append(multiXyCoordinates, xyCoordinates)
+		}
+	}
+	return multiXyCoordinates
+}
+
+func makeCoord(point [2]float64) geometry.Coord {
+	return geometry.Coord{point[0], point[1]}
+}