diff --git a/src/estimator.cpp b/src/estimator.cpp
index 4836251..2ba20dd 100644
--- a/src/estimator.cpp
+++ b/src/estimator.cpp
@@ -34,6 +34,9 @@ class Callback {
           indices.push_back(i);
 
         // v = eg_1 ^ eg_2 is the plan normal
+        //TODO !!! eg_3 is also the plan normal :-)
+        // the code hereunder should work :
+        // Eigen::Vector3f v = eg.col(2);
         Eigen::Vector3f v = eg.col(0).cross(eg.col(1));
         // norm(v) == 1
         v.normalize();