--- a/pkg/octree/tree.go	Mon Oct 14 13:18:15 2019 +0200
+++ b/pkg/octree/tree.go	Mon Oct 14 14:58:04 2019 +0200
@@ -312,51 +312,3 @@
 		}
 	}
 }
-
-func (ot *Tree) Diff(other *Tree) PointMap {
-
-	firstVs, secondVs := ot.Vertices(), other.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 := ot.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
-}