use update.. in FactorBase::link

src/factor/factor_base.cpp

@@ -252,14 +252,13 @@ void FactorBase::link(FeatureBasePtr _ftr_ptr)
         return;
     }
 
-    // copy measurement_ and measurement_sqrt_information_upper_
-    measurement_ = _ftr_ptr->getMeasurement();
-    measurement_sqrt_information_upper_ = _ftr_ptr->getMeasurementSquareRootInformationUpper();
-
     // link with feature
     _ftr_ptr->addFactor(shared_from_this());
     this->setFeature(_ftr_ptr);
 
+    // update measurement and info according to the feature
+    updateMeasurementAndSquareRootInformationUpper();
+
     // if frame, should be key
     if (getCapture() and getFrame())
         assert(getFrame()->isKey() && "Forbidden: linking a factor with a non-key frame.");