From bddd7e68eba3b85daf8f1ae8d4888acd83916c62 Mon Sep 17 00:00:00 2001
From: John Lambert <johnwl@stanford.edu>
Date: Wed, 10 Mar 2021 09:45:19 -0500
Subject: [PATCH] add const on Rot3

---
 gtsam/geometry/Similarity3.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gtsam/geometry/Similarity3.cpp b/gtsam/geometry/Similarity3.cpp
index ded917933..c76b8eb32 100644
--- a/gtsam/geometry/Similarity3.cpp
+++ b/gtsam/geometry/Similarity3.cpp
@@ -180,10 +180,11 @@ Similarity3 Similarity3::Align(const vector<Pose3Pair> &abPosePairs) {
   Point3Pairs abPointPairs;
   rotations.reserve(n);
   abPointPairs.reserve(n);
+  // note that frame "i" is the i'th object/camera/etc body frame
   Pose3 aTi, bTi;
   for (const Pose3Pair &abPair : abPosePairs) {
     std::tie(aTi, bTi) = abPair;
-    Rot3 aRb = aTi.rotation().compose(bTi.rotation().inverse());
+    const Rot3 aRb = aTi.rotation().compose(bTi.rotation().inverse());
     rotations.emplace_back(aRb);
     abPointPairs.emplace_back(aTi.translation(), bTi.translation());
   }