diff --git a/source/engine/viewer/viewermodel.js b/source/engine/viewer/viewermodel.js
index 4c951ba..b8454cf 100644
--- a/source/engine/viewer/viewermodel.js
+++ b/source/engine/viewer/viewermodel.js
@@ -121,6 +121,7 @@ export class ViewerMainModel
         this.edgeSettings = new EdgeSettings (false, new RGBColor (0, 0, 0), 1);
         this.hasLines = false;
         this.hasPolygonOffset = false;
+        this.fullBoundingBox = null;
     }
 
     SetMainObject (mainObject)
@@ -128,6 +129,7 @@ export class ViewerMainModel
         this.mainModel.SetRootObject (mainObject);
         this.hasLines = false;
         this.hasPolygonOffset = false;
+        this.fullBoundingBox = null;
 
         this.EnumerateLines ((line) => {
             this.hasLines = true;
@@ -192,6 +194,17 @@ export class ViewerMainModel
         this.UpdatePolygonOffset ();
     }
 
+    GetFullBoundingBox ()
+    {
+        if (this.fullBoundingBox !== null) {
+            return this.fullBoundingBox;
+        }
+        this.fullBoundingBox = this.GetBoundingBox (() => {
+            return true;
+        });
+        return this.fullBoundingBox;
+    }
+
     GetBoundingBox (needToProcess)
     {
         let hasMesh = false;
@@ -292,6 +305,18 @@ export class ViewerMainModel
 
     GetMeshIntersectionUnderMouse (mouseCoords, camera, width, height)
     {
+        function CalculateLineThreshold (mousePos, camera, boundingBoxCenter)
+        {
+            let thresholdInScreenCoordinates = 15.0;
+            let frustumRange = camera.far - camera.near;
+            let cameraDistanceFromCenter = boundingBoxCenter.distanceTo (camera.position);
+            let distanceInFrustumRatio = cameraDistanceFromCenter / frustumRange;
+            let zValue = -1.0 + 2.0 * distanceInFrustumRatio;
+            let referencePoint1 = new THREE.Vector3 (mousePos.x, mousePos.y, zValue).unproject (camera);
+            let referencePoint2 = new THREE.Vector3 (mousePos.x + thresholdInScreenCoordinates, mousePos.y, zValue).unproject (camera);
+            return referencePoint1.distanceTo (referencePoint2);
+        }
+
         if (this.mainModel.IsEmpty ()) {
             return null;
         }
@@ -300,17 +325,20 @@ export class ViewerMainModel
             return null;
         }
 
-        let raycaster = new THREE.Raycaster ();
-        if (this.hasLines) {
-            let boundingSphere = this.GetBoundingSphere (() => {
-                return true;
-            });
-            raycaster.params.Line.threshold = boundingSphere.radius / 100.0;
-        }
-
         let mousePos = new THREE.Vector2 ();
         mousePos.x = (mouseCoords.x / width) * 2 - 1;
         mousePos.y = -(mouseCoords.y / height) * 2 + 1;
+
+        let raycaster = new THREE.Raycaster ();
+        if (this.hasLines) {
+            let boundingBox = this.GetFullBoundingBox ();
+            if (boundingBox !== null) {
+                let boundingBoxCenter = new THREE.Vector3 (0.0, 0.0, 0.0);
+                boundingBox.getCenter (boundingBoxCenter);
+                raycaster.params.Line.threshold = CalculateLineThreshold (mousePos, camera, boundingBoxCenter);
+            }
+        }
+
         raycaster.setFromCamera (mousePos, camera);
         let iSectObjects = raycaster.intersectObject (this.mainModel.GetRootObject (), true);
         for (let i = 0; i < iSectObjects.length; i++) {