message: Add check that squared distance-threshold value is non-negative.
diff: @@ -296,6 +296,8 @@ public:
  */
  void setSquaredDistanceThreshold(double sqThreshold)
  {
  + SLIC_ERROR_IF(sqThreshold < 0.0,
  + "Squared distance-threshold must be non-negative.");
  m_sqDistanceThreshold = sqThreshold;
  }
  