Address the comments.

cartographer/internal/mapping/global_trajectory_builder.cc

@@ -48,7 +48,7 @@ class GlobalTrajectoryBuilder : public mapping::TrajectoryBuilderInterface {
       const std::string& sensor_id,
       const sensor::TimedPointCloudData& timed_point_cloud_data) override {
     CHECK(local_trajectory_builder_)
-        << "Cannot add TimedPointCloudData without a LocalTrajectoryBuilder2D.";
+        << "Cannot add TimedPointCloudData without a LocalTrajectoryBuilder.";
     std::unique_ptr<typename LocalTrajectoryBuilder::MatchingResult>
         matching_result = local_trajectory_builder_->AddRangeData(
             timed_point_cloud_data.time,

cartographer/mapping/scan_matching/real_time_correlative_scan_matcher.cc

@@ -0,0 +1,26 @@
+#include "cartographer/mapping/scan_matching/real_time_correlative_scan_matcher.h"
+
+namespace cartographer {
+namespace mapping {
+namespace scan_matching {
+
+proto::RealTimeCorrelativeScanMatcherOptions
+CreateRealTimeCorrelativeScanMatcherOptions(
+    common::LuaParameterDictionary* const parameter_dictionary) {
+  proto::RealTimeCorrelativeScanMatcherOptions options;
+  options.set_linear_search_window(
+      parameter_dictionary->GetDouble("linear_search_window"));
+  options.set_angular_search_window(
+      parameter_dictionary->GetDouble("angular_search_window"));
+  options.set_translation_delta_cost_weight(
+      parameter_dictionary->GetDouble("translation_delta_cost_weight"));
+  options.set_rotation_delta_cost_weight(
+      parameter_dictionary->GetDouble("rotation_delta_cost_weight"));
+  CHECK_GE(options.translation_delta_cost_weight(), 0.);
+  CHECK_GE(options.rotation_delta_cost_weight(), 0.);
+  return options;
+}
+
+}  // namespace scan_matching
+}  // namespace mapping
+}  // namespace cartographer

cartographer/mapping/scan_matching/real_time_correlative_scan_matcher.h

@@ -0,0 +1,36 @@
+
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef CARTOGRAPHER_MAPPING_SCAN_MATCHING_REAL_TIME_CORRELATIVE_SCAN_MATCHER_H_
+#define CARTOGRAPHER_MAPPING_SCAN_MATCHING_REAL_TIME_CORRELATIVE_SCAN_MATCHER_H_
+
+#include "cartographer/common/lua_parameter_dictionary.h"
+#include "cartographer/mapping/scan_matching/proto/real_time_correlative_scan_matcher_options.pb.h"
+
+namespace cartographer {
+namespace mapping {
+namespace scan_matching {
+
+proto::RealTimeCorrelativeScanMatcherOptions
+CreateRealTimeCorrelativeScanMatcherOptions(
+    common::LuaParameterDictionary* const parameter_dictionary);
+
+}  // namespace scan_matching
+}  // namespace mapping
+}  // namespace cartographer
+
+#endif  // CARTOGRAPHER_MAPPING_SCAN_MATCHING_REAL_TIME_CORRELATIVE_SCAN_MATCHER_H_

cartographer/mapping/trajectory_builder_interface.h

@@ -107,7 +107,7 @@ class TrajectoryBuilderInterface {
                              const sensor::LandmarkData& landmark_data) = 0;
   // Allows to directly add local SLAM results to the 'PoseGraph'. Note that it
   // is invalid to add local SLAM results for a trajectory that has a
-  // 'LocalTrajectoryBuilder2D'.
+  // 'LocalTrajectoryBuilder2D/3D'.
   virtual void AddLocalSlamResultData(
       std::unique_ptr<mapping::LocalSlamResultData> local_slam_result_data) = 0;
 };

cartographer/mapping_2d/scan_matching/real_time_correlative_scan_matcher_2d.cc

@@ -33,23 +33,6 @@ namespace cartographer {
 namespace mapping {
 namespace scan_matching {
 
-proto::RealTimeCorrelativeScanMatcherOptions
-CreateRealTimeCorrelativeScanMatcherOptions(
-    common::LuaParameterDictionary* const parameter_dictionary) {
-  proto::RealTimeCorrelativeScanMatcherOptions options;
-  options.set_linear_search_window(
-      parameter_dictionary->GetDouble("linear_search_window"));
-  options.set_angular_search_window(
-      parameter_dictionary->GetDouble("angular_search_window"));
-  options.set_translation_delta_cost_weight(
-      parameter_dictionary->GetDouble("translation_delta_cost_weight"));
-  options.set_rotation_delta_cost_weight(
-      parameter_dictionary->GetDouble("rotation_delta_cost_weight"));
-  CHECK_GE(options.translation_delta_cost_weight(), 0.);
-  CHECK_GE(options.rotation_delta_cost_weight(), 0.);
-  return options;
-}
-
 RealTimeCorrelativeScanMatcher2D::RealTimeCorrelativeScanMatcher2D(
     const proto::RealTimeCorrelativeScanMatcherOptions& options)
     : options_(options) {}

cartographer/mapping_2d/scan_matching/real_time_correlative_scan_matcher_2d.h

@@ -42,17 +42,14 @@
 
 #include "Eigen/Core"
 #include "cartographer/mapping/scan_matching/proto/real_time_correlative_scan_matcher_options.pb.h"
+#include "cartographer/mapping/scan_matching/real_time_correlative_scan_matcher.h"
 #include "cartographer/mapping_2d/probability_grid.h"
 #include "cartographer/mapping_2d/scan_matching/correlative_scan_matcher_2d.h"
 
 namespace cartographer {
 namespace mapping {
 namespace scan_matching {
 
-proto::RealTimeCorrelativeScanMatcherOptions
-CreateRealTimeCorrelativeScanMatcherOptions(
-    common::LuaParameterDictionary* const parameter_dictionary);
-
 // An implementation of "Real-Time Correlative Scan Matching" by Olson.
 class RealTimeCorrelativeScanMatcher2D {
  public:

cartographer/mapping_2d/scan_matching/translation_delta_cost_functor_2d.h

@@ -43,7 +43,7 @@ class TranslationDeltaCostFunctor2D {
   }
 
  private:
-  // Constructs a new TranslationDeltaCostFunctor from the given
+  // Constructs a new TranslationDeltaCostFunctor2D from the given
   // 'target_translation' (x, y).
   explicit TranslationDeltaCostFunctor2D(
       const double scaling_factor, const Eigen::Vector2d& target_translation)

cartographer/mapping_3d/local_trajectory_builder_options_3d.cc

@@ -17,7 +17,7 @@
 #include "cartographer/mapping_3d/local_trajectory_builder_options_3d.h"
 
 #include "cartographer/internal/mapping/motion_filter.h"
-#include "cartographer/mapping_2d/scan_matching/real_time_correlative_scan_matcher_2d.h"
+#include "cartographer/mapping/scan_matching/real_time_correlative_scan_matcher.h"
 #include "cartographer/mapping_3d/scan_matching/ceres_scan_matcher.h"
 #include "cartographer/mapping_3d/submap_3d.h"
 #include "cartographer/sensor/voxel_filter.h"