rpc 参数求解

pkg/dem/dem.go

@@ -38,7 +38,7 @@ func (d *Dem1Km) Load() error {
 
 	structure := band.Structure()
 
-	for y := 1; y <= structure.SizeY; y++ {
+	for y := 0; y < structure.SizeY; y++ {
 		scanline := make([]float32, structure.SizeX)
 		err = band.Read(0, y, scanline, structure.SizeX, 1)
 		if err != nil {
@@ -68,3 +68,34 @@ func (d *Dem1Km) Elevation(lng, lat float64) float32 {
 	return d.LT[h][w]
 
 }
+
+func (d *Dem1Km) MinMaxElevationInRect(lng1, lat1, lng2, lat2 float64) (float64, float64) {
+	minElev := math.MaxFloat32
+	maxElev := -math.MaxFloat32
+
+	lng1 = math.Abs(lng1 + 180.0)
+	lat1 = math.Abs(lat1 - 90.0)
+	w1 := int(lng1 / float64(d.wUnit))
+	h1 := int(lat1 / float64(d.hUnit))
+
+	lng2 = math.Abs(lng2 + 180.0)
+	lat2 = math.Abs(lat2 - 90.0)
+	w2 := int(lng2 / float64(d.wUnit))
+	h2 := int(lat2 / float64(d.hUnit))
+
+	if w1 > d.width-1 || h1 > d.height-1 || w2 > d.width-1 || h2 > d.height-1 {
+		return 0.0, 0.0
+	}
+
+	for w := w1; w <= w2; w++ {
+		for h := h1; h <= h2; h++ {
+			if d.LT[h][w] < float32(minElev) {
+				minElev = float64(d.LT[h][w])
+			}
+			if d.LT[h][w] > float32(maxElev) {
+				maxElev = float64(d.LT[h][w])
+			}
+		}
+	}
+	return minElev, maxElev
+}

pkg/dem/dem_test.go

@@ -0,0 +1,23 @@
+package dem_test
+
+import (
+	"testing"
+
+	"github.com/airbusgeo/godal"
+	"starwiz.cn/sjy01/image-proc/pkg/dem"
+)
+
+func init() {
+	godal.RegisterAll()
+}
+
+func TestDem(t *testing.T) {
+	t.Log("TestDem")
+	d := dem.NewDem1Km("../../dem/gdlebm.tif")
+	// 珠穆朗玛 经纬度：27°59′17″ N ；86°55′31″ E
+	elv := d.Elevation(86+55.0/60.0+31.0/3600.0, 27+59.0/60.0+17.0/3600.0)
+	t.Log("elv:", elv)
+	if elv < 8000 {
+		t.Fail()
+	}
+}