Use abc terminology

gtsam/sfm/TransferFactor.h

@@ -26,59 +26,56 @@ namespace gtsam {
  * Binary factor in the context of Structure from Motion (SfM).
  * It is used to transfer points between different views based on the
  * fundamental matrices between these views. The factor computes the error
- * between the transferred points `pi` and `pj`, and the actual point `pk` in
+ * between the transferred points `pa` and `pb`, and the actual point `pc` in
  * the target view. Jacobians are done using numerical differentiation.
  */
 template <typename F>
 class TransferFactor : public NoiseModelFactorN<F, F> {
   EdgeKey key1_, key2_;  ///< the two EdgeKeys
-  Point2 pi, pj, pk;     ///< The points in the three views
+  Point2 pa, pb, pc;     ///< The points in the three views
 
  public:
   /**
    * @brief Constructor for the TransferFactor class.
    *
    * Uses EdgeKeys to determine how to use the two fundamental matrix unknowns
-   * F1 and F2, to transfer points pi and pj to the third view, and minimize the
-   * difference with pk.
+   * F1 and F2, to transfer points pa and pb to the third view, and minimize the
+   * difference with pc.
    *
    * The edge keys must represent valid edges for the transfer operation,
    * specifically one of the following configurations:
-   * - (i, k) and (j, k)
-   * - (i, k) and (k, j)
-   * - (k, i) and (j, k)
-   * - (k, i) and (k, j)
+   * - (a, c) and (b, c)
+   * - (a, c) and (c, b)
+   * - (c, a) and (b, c)
+   * - (c, a) and (c, b)
    *
-   * @param key1 First EdgeKey specifying F1: (i, k) or (k, i).
-   * @param key2 Second EdgeKey specifying F2: (j, k) or (k, j).
-   * @param pi The point in the first view (i).
-   * @param pj The point in the second view (j).
-   * @param pk The point in the third (and transfer target) view (k).
+   * @param key1 First EdgeKey specifying F1: (a, c) or (c, a).
+   * @param key2 Second EdgeKey specifying F2: (b, c) or (c, b).
+   * @param pa The point in the first view (a).
+   * @param pb The point in the second view (b).
+   * @param pc The point in the third (and transfer target) view (c).
    * @param model An optional SharedNoiseModel that defines the noise model
    *              for this factor. Defaults to nullptr.
    */
-  TransferFactor(EdgeKey key1, EdgeKey key2, const Point2& pi, const Point2& pj,
-                 const Point2& pk, const SharedNoiseModel& model = nullptr)
+  TransferFactor(EdgeKey key1, EdgeKey key2, const Point2& pa, const Point2& pb,
+                 const Point2& pc, const SharedNoiseModel& model = nullptr)
       : NoiseModelFactorN<F, F>(model, key1, key2),
         key1_(key1),
         key2_(key2),
-        pi(pi),
-        pj(pj),
-        pk(pk) {}
+        pa(pa),
+        pb(pb),
+        pc(pc) {}
 
   // Create Matrix3 objects based on EdgeKey configurations
-  static std::pair<Matrix3, Matrix3> getMatrices(const EdgeKey& key1,
-                                                 const F& F1,
-                                                 const EdgeKey& key2,
-                                                 const F& F2) {
-    // Fill Fki and Fkj based on EdgeKey configurations
-    if (key1.i() == key2.i()) {
+  std::pair<Matrix3, Matrix3> getMatrices(const F& F1, const F& F2) const {
+    // Fill Fca and Fcb based on EdgeKey configurations
+    if (key1_.i() == key2_.i()) {
       return {F1.matrix(), F2.matrix()};
-    } else if (key1.i() == key2.j()) {
+    } else if (key1_.i() == key2_.j()) {
       return {F1.matrix(), F2.matrix().transpose()};
-    } else if (key1.j() == key2.i()) {
+    } else if (key1_.j() == key2_.i()) {
       return {F1.matrix().transpose(), F2.matrix()};
-    } else if (key1.j() == key2.j()) {
+    } else if (key1_.j() == key2_.j()) {
       return {F1.matrix().transpose(), F2.matrix().transpose()};
     } else {
       throw std::runtime_error(
@@ -91,13 +88,13 @@ class TransferFactor : public NoiseModelFactorN<F, F> {
                        OptionalMatrixType H1 = nullptr,
                        OptionalMatrixType H2 = nullptr) const override {
     std::function<Point2(F, F)> transfer = [&](const F& F1, const F& F2) {
-      auto [Fki, Fkj] = getMatrices(key1_, F1, key2_, F2);
-      return Transfer(Fki, pi, Fkj, pj);
+      auto [Fca, Fcb] = getMatrices(F1, F2);
+      return Transfer(Fca, pa, Fcb, pb);
     };
     if (H1) *H1 = numericalDerivative21<Point2, F, F>(transfer, F1, F2);
     if (H2) *H2 = numericalDerivative22<Point2, F, F>(transfer, F1, F2);
-    return transfer(F1, F2) - pk;
+    return transfer(F1, F2) - pc;
   }
 };
 
-}  // namespace gtsam
+}  // namespace gtsam

gtsam/sfm/tests/testTransferFactor.cpp

@@ -71,7 +71,7 @@ TEST(TransferFactor, Jacobians) {
       factor2{key20, key12, p[0], p[1], p[2]};
 
   // Check that getMatrices is correct
-  auto [Fki, Fkj] = factor2.getMatrices(key20, triplet.Fca, key12, triplet.Fbc);
+  auto [Fki, Fkj] = factor2.getMatrices(triplet.Fca, triplet.Fbc);
   EXPECT(assert_equal<Matrix3>(triplet.Fca.matrix(), Fki));
   EXPECT(assert_equal<Matrix3>(triplet.Fbc.matrix().transpose(), Fkj));