--- a/python/prediction.py	Tue Jul 23 05:05:06 2013 -0400
+++ b/python/prediction.py	Wed Jul 24 12:48:12 2013 -0400
@@ -313,8 +313,8 @@
     '''Prediction parameters of prediction at constant velocity
     using direct computation of the intersecting point'''
     
-    def __init__(self, maxSpeed):
-        PredictionParameters.__init__(self, 'constant velocity (direct computation)', maxSpeed)
+    def __init__(self):
+        PredictionParameters.__init__(self, 'constant velocity (direct computation)', None)
 
     def computeCrossingsCollisionsAtInstant(self, currentInstant, obj1, obj2, collisionDistanceThreshold, timeHorizon, computeCZ = False, debug = False):
         collisionPoints = []
@@ -341,10 +341,10 @@
                     timeInterval1 = moving.TimeInterval(max(0,dist1-halfCollisionDistanceThreshold)/s1, (dist1+halfCollisionDistanceThreshold)/s1)
                     timeInterval2 = moving.TimeInterval(max(0,dist2-halfCollisionDistanceThreshold)/s2, (dist2+halfCollisionDistanceThreshold)/s2)
                     collisionTimeInterval = moving.TimeInterval.intersection(timeInterval1, timeInterval2)
-                    if not collisionTimeInterval.empty():
+                    if computeCZ and collisionTimeInterval.empty():
+                        crossingZones = [SafetyPoint(intersection, 1., timeInterval1.distance(timeInterval2))]
+                    else:
                         collisionPoints = [SafetyPoint(intersection, 1., collisionTimeInterval.center())]
-                    else:
-                        crossingZones = [SafetyPoint(intersection, 1., timeInterval1.distance(timeInterval2))]
     
         if debug and intersection!= None:
             from matplotlib.pyplot import plot, figure, axis, title