locationtech · bjornharrtell · May 3, 2021 · May 4, 2021 · May 4, 2021 · Aug 19, 2021
diff --git a/modules/core/src/main/java/org/locationtech/jts/algorithm/RobustLineIntersector.java b/modules/core/src/main/java/org/locationtech/jts/algorithm/RobustLineIntersector.java
@@ -16,6 +16,7 @@
  */
 import org.locationtech.jts.geom.Coordinate;
 import org.locationtech.jts.geom.Envelope;
+import org.locationtech.jts.geom.ZInterpolating;
 
 /**
  * A robust version of {@link LineIntersector}.
@@ -25,7 +26,6 @@
 public class RobustLineIntersector
     extends LineIntersector
 {
-
   public RobustLineIntersector() {
   }
 
@@ -414,6 +414,8 @@ private static double zGetOrInterpolate(Coordinate p, Coordinate p1, Coordinate
    * @return the interpolated Z value (may be NaN)
    */
   private static double zInterpolate(Coordinate p, Coordinate p1, Coordinate p2) {
+    if (!ZInterpolating.getZInterpolating())
+      return Double.NaN;
     double p1z = p1.getZ();
     double p2z = p2.getZ();
     if (Double.isNaN(p1z)) {

diff --git a/modules/core/src/main/java/org/locationtech/jts/geom/ZInterpolating.java b/modules/core/src/main/java/org/locationtech/jts/geom/ZInterpolating.java
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2016 Vivid Solutions.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * and Eclipse Distribution License v. 1.0 which accompanies this distribution.
+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
+ * and the Eclipse Distribution License is available at
+ *
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ */
+package org.locationtech.jts.geom;
+
+/**
+ * Internal class which encapsulates the runtime switch to Z-interpolate when applicable.
+ * <p>
+ * <ul>
+ * <li><code>jts.zinterpolating=false</code> - (default) do not Z-interpolate
+ * <li><code>jts.zinterpolating=true</code> - Z-interpolate
+ * </ul>
+ * 
+ * @author bjornharrtell
+ *
+ */
+public class ZInterpolating {
+    public static String ZINTERPOLATING_PROPERTY_NAME = "jts.zinterpolating";
+    public static String ZINTERPOLATING_PROPERTY_VALUE_TRUE = "true";
+    public static String ZINTERPOLATING_PROPERTY_VALUE_FALSE = "false";
+    public static boolean ZINTERPOLATING_DEFAULT = true;
+    private static boolean isZInterpolating = ZINTERPOLATING_DEFAULT;
+
+    static {
+        setZInterpolatingImpl(System.getProperty(ZINTERPOLATING_PROPERTY_NAME));
+    }
+
+    public static boolean getZInterpolating() {
+        return isZInterpolating;
+    }
+
+    public static void setZInterpolating(boolean zInterpolating) {
+        isZInterpolating = zInterpolating;
+    }
+
+    private static void setZInterpolatingImpl(String isZInterpolatingCode) {
+        if (isZInterpolatingCode == null)
+            return;
+            isZInterpolating = ZINTERPOLATING_DEFAULT;
+        if (ZINTERPOLATING_PROPERTY_VALUE_TRUE.equalsIgnoreCase(isZInterpolatingCode))
+            isZInterpolating = true;
+    }
+}
diff --git a/modules/core/src/main/java/org/locationtech/jts/operation/overlayng/ElevationModel.java b/modules/core/src/main/java/org/locationtech/jts/operation/overlayng/ElevationModel.java
@@ -16,6 +16,7 @@
 import org.locationtech.jts.geom.CoordinateSequenceFilter;
 import org.locationtech.jts.geom.Envelope;
 import org.locationtech.jts.geom.Geometry;
+import org.locationtech.jts.geom.ZInterpolating;
 import org.locationtech.jts.math.MathUtil;
 
 /**
@@ -192,6 +193,10 @@ public double getZ(double x, double y) {
    * @param geom the geometry to populate Z values for
    */
   public void populateZ(Geometry geom) {
+    // short-circuit if ZInterpolation is globally turned off
+    if (!ZInterpolating.getZInterpolating())
+      return;
+
     // short-circuit if no Zs are present in model
     if (! hasZValue)
       return;

diff --git a/modules/core/src/main/java/org/locationtech/jts/operation/overlayng/OverlayNG.java b/modules/core/src/main/java/org/locationtech/jts/operation/overlayng/OverlayNG.java
@@ -486,7 +486,7 @@ else if (! inputGeom.isSingle() &&  inputGeom.hasPoints()) {
       result = computeEdgeOverlay();
     }
     /**
-     * This is a no-op if the elevation model was not computed due to Z not present
+     * This is a no-op if the elevation model was not computed due to Z not present or if Z interpolation is turned off
      */
     elevModel.populateZ(result);
     return result;