--- a/pkg/octree/strtree.go	Sat Oct 19 23:07:59 2019 +0200
+++ b/pkg/octree/strtree.go	Mon Oct 21 02:01:56 2019 +0200
@@ -484,51 +484,3 @@
 	}
 	return int32(-(pos + 1))
 }
-
-func (s *STRTree) Diff(other *STRTree) PointMap {
-
-	firstVs, secondVs := s.tin.Vertices, other.tin.Vertices
-
-	result := make(PointMap, len(firstVs)+len(secondVs))
-
-	sliceWork(
-		firstVs,
-		result,
-		func(slice []Vertex, turn func([]Vertex) []Vertex) {
-			p := turn(nil)
-			for i := range slice {
-				v := &slice[i]
-				if z, found := other.Value(v.X, v.Y); found {
-					p = append(p, Vertex{v.X, v.Y, v.Z - z})
-					if len(p) == cap(p) {
-						p = turn(p)
-					}
-				}
-			}
-			if len(p) > 0 {
-				turn(p)
-			}
-		})
-
-	sliceWork(
-		secondVs,
-		result,
-		func(
-			slice []Vertex, turn func([]Vertex) []Vertex) {
-			p := turn(nil)
-			for i := range slice {
-				v := &slice[i]
-				if z, found := s.Value(v.X, v.Y); found {
-					p = append(p, Vertex{v.X, v.Y, z - v.Z})
-					if len(p) == cap(p) {
-						p = turn(p)
-					}
-				}
-			}
-			if len(p) > 0 {
-				turn(p)
-			}
-		})
-
-	return result
-}