diff --git a/README.md b/README.md
index fa2a062..74b7eb6 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ Core modules:
     2. Crop ROI of point clouds.
     3. Project point clouds into a plane. 
 - `features`:
-    1. Edge points detection from point clouds.
+    1. Boundary points detection from point clouds.
 - `registration`:
     1. Corresponding matching with descriptors.
     2. 3D rigid transformation solver including SVD, RANSAC and [TEASERPP](https://github.com/MIT-SPARK/TEASER-plusplus).
@@ -89,10 +89,10 @@ pcd_plane = m3d.preprocessing.project_into_plane(pcd)
 ```
 
 ```python
-# edge points detection
-index = m3d.features.detect_edge_points(
+# boundary points detection
+index = m3d.features.detect_boundary_points(
     pcd, o3d.geometry.KDTreeSearchParamHybrid(0.02, 30))
-edges = pcd.select_by_index(index)
+boundary = pcd.select_by_index(index)
 ```
 
 ```python
diff --git a/examples/cpp/CMakeLists.txt b/examples/cpp/CMakeLists.txt
index 5084c2d..398dfcb 100644
--- a/examples/cpp/CMakeLists.txt
+++ b/examples/cpp/CMakeLists.txt
@@ -10,8 +10,8 @@ target_link_libraries(ppf_estimator PUBLIC misc3d::misc3d)
 add_executable(preprocessing preprocessing.cpp)
 target_link_libraries(preprocessing PUBLIC misc3d::misc3d)
 
-add_executable(ransac_and_edge ransac_and_edge.cpp)
-target_link_libraries(ransac_and_edge PUBLIC misc3d::misc3d)
+add_executable(ransac_and_boundary ransac_and_boundary.cpp)
+target_link_libraries(ransac_and_boundary PUBLIC misc3d::misc3d)
 
 add_executable(segmentation segmentation.cpp)
 target_link_libraries(segmentation PUBLIC misc3d::misc3d)
@@ -20,5 +20,5 @@ add_executable(transform_estimation transform_estimation.cpp)
 target_link_libraries(transform_estimation PUBLIC misc3d::misc3d)
 
 install(TARGETS farthest_point_sampling normal_estimation ppf_estimator 
-                preprocessing ransac_and_edge segmentation transform_estimation
+                preprocessing ransac_and_boundary segmentation transform_estimation
                 RUNTIME DESTINATION "${CMAKE_INSTALL_PREFIX}/misc3d/bin")
\ No newline at end of file
diff --git a/examples/cpp/ransac_and_edge.cpp b/examples/cpp/ransac_and_boundary.cpp
similarity index 83%
rename from examples/cpp/ransac_and_edge.cpp
rename to examples/cpp/ransac_and_boundary.cpp
index 41fa36b..0c73b4a 100644
--- a/examples/cpp/ransac_and_edge.cpp
+++ b/examples/cpp/ransac_and_boundary.cpp
@@ -2,7 +2,7 @@
 #include <memory>
 
 #include <misc3d/common/ransac.h>
-#include <misc3d/features/edge_detection.h>
+#include <misc3d/features/boundary_detection.h>
 #include <misc3d/utils.h>
 #include <misc3d/vis/vis_utils.h>
 #include <open3d/camera/PinholeCameraIntrinsic.h>
@@ -43,20 +43,20 @@ int main(int argc, char *argv[]) {
 
     auto pcd_plane = pcd_down->SelectByIndex(inliers);
     timer.Start();
-    auto indices = misc3d::features::DetectEdgePoints(
+    auto indices = misc3d::features::DetectBoundaryPoints(
         *pcd_plane, open3d::geometry::KDTreeSearchParamHybrid(0.02, 30));
-    std::cout << "Time cost for edge detection: " << timer.Stop() << std::endl;
+    std::cout << "Time cost for boundary detection: " << timer.Stop() << std::endl;
 
-    auto pcd_edges = pcd_plane->SelectByIndex(indices);
+    auto boundary = pcd_plane->SelectByIndex(indices);
 
     auto vis = std::make_shared<open3d::visualization::Visualizer>();
-    vis->CreateVisualizerWindow("Ransac and edge detection", 1920, 1200);
+    vis->CreateVisualizerWindow("Ransac and boundary detection", 1920, 1200);
     misc3d::vis::DrawGeometry3D(vis, pcd_down, {0.5, 0.5, 0.5});
     misc3d::vis::DrawGeometry3D(vis, pcd_plane);
     auto bbox = std::make_shared<open3d::geometry::OrientedBoundingBox>(
         pcd_plane->GetOrientedBoundingBox());
     misc3d::vis::DrawGeometry3D(vis, bbox, {0, 1, 0});
-    misc3d::vis::DrawGeometry3D(vis, pcd_edges, {1, 0, 0});
+    misc3d::vis::DrawGeometry3D(vis, boundary, {1, 0, 0});
     vis->Run();
 
     return 0;
diff --git a/examples/python/ransac_and_edge.py b/examples/python/ransac_and_boundary.py
similarity index 82%
rename from examples/python/ransac_and_edge.py
rename to examples/python/ransac_and_boundary.py
index de9acb9..b414bca 100644
--- a/examples/python/ransac_and_edge.py
+++ b/examples/python/ransac_and_boundary.py
@@ -9,7 +9,7 @@
 
 
 vis = o3d.visualization.Visualizer()
-vis.create_window("Segmentation", 1920, 1200)
+vis.create_window("Ransac and Bounary Detection", 1920, 1200)
 
 depth = o3d.io.read_image('../data/indoor/depth/depth_0.png')
 color = o3d.io.read_image('../data/indoor/color/color_0.png')
@@ -33,17 +33,17 @@
 plane = pcd.select_by_index(index)
 
 t1 = time.time()
-index = m3d.features.detect_edge_points(
+index = m3d.features.detect_boundary_points(
     plane, o3d.geometry.KDTreeSearchParamHybrid(0.02, 30))
-print('Edges detection time: %.3f' % (time.time() - t1))
+print('Boundary detection time: %.3f' % (time.time() - t1))
 
-edges = plane.select_by_index(index)
+boundary = plane.select_by_index(index)
 
 # scene points painted with gray
 bbox = plane.get_oriented_bounding_box()
 m3d.vis.draw_geometry3d(vis, pcd, color=(0.5, 0.5, 0.5))
 m3d.vis.draw_geometry3d(vis, bbox, color=(0, 1, 0))
 m3d.vis.draw_geometry3d(vis, plane)
-m3d.vis.draw_geometry3d(vis, edges, color=(1, 0, 0), size=5)
+m3d.vis.draw_geometry3d(vis, boundary, color=(1, 0, 0), size=5)
 
 vis.run()
diff --git a/include/misc3d/common/knn.h b/include/misc3d/common/knn.h
index 3527de2..aa15df8 100644
--- a/include/misc3d/common/knn.h
+++ b/include/misc3d/common/knn.h
@@ -13,6 +13,14 @@ namespace misc3d {
 
 namespace common {
 
+/**
+ * @brief This is a K nearest neighbor search class based on annoy.
+ * It is recommanded to use this class instead of the KDTreeFlann class when the
+ * feature dimension is large, eg. for descriptor-based feature matching usage
+ * As for point cloud based nearest neighbor search, the KDTreeFlann class is
+ * more suitable.
+ *
+ */
 class KNearestSearch {
 public:
     KNearestSearch();
@@ -21,8 +29,7 @@ class KNearestSearch {
 
     KNearestSearch(const Eigen::MatrixXd &data, int n_trees = 4);
 
-    KNearestSearch(const open3d::geometry::Geometry &geometry,
-                   int n_trees = 4);
+    KNearestSearch(const open3d::geometry::Geometry &geometry, int n_trees = 4);
 
     KNearestSearch(const open3d::pipelines::registration::Feature &feature,
                    int n_trees = 4);
diff --git a/include/misc3d/features/edge_detection.h b/include/misc3d/features/boundary_detection.h
similarity index 86%
rename from include/misc3d/features/edge_detection.h
rename to include/misc3d/features/boundary_detection.h
index dbcc39d..3a6f417 100644
--- a/include/misc3d/features/edge_detection.h
+++ b/include/misc3d/features/boundary_detection.h
@@ -12,14 +12,14 @@ namespace misc3d {
 namespace features {
 
 /**
- * @brief Detect edges from point clouds
+ * @brief Detect boundary from point clouds
  *
  * @param pc
  * @param param nearest neighbor search parameter
  * @param angle_threshold angle threshold to decide if a point is a boundary point
  * @return std::vector<size_t>
  */
-std::vector<size_t> DetectEdgePoints(
+std::vector<size_t> DetectBoundaryPoints(
     const open3d::geometry::PointCloud& pc,
     const open3d::geometry::KDTreeSearchParam& param, double angle_threshold = 90.0);
 
diff --git a/python/py_features.cpp b/python/py_features.cpp
index 7f502b3..f0a4d04 100644
--- a/python/py_features.cpp
+++ b/python/py_features.cpp
@@ -1,6 +1,6 @@
 #include <py_misc3d.h>
 
-#include <misc3d/features/edge_detection.h>
+#include <misc3d/features/boundary_detection.h>
 #include <misc3d/utils.h>
 
 namespace misc3d {
@@ -9,11 +9,11 @@ namespace features {
 
 void pybind_features(py::module& m) {
     m.def(
-        "detect_edge_points",
+        "detect_boundary_points",
         [](const PointCloudPtr& pc,
            const open3d::geometry::KDTreeSearchParam& param,
            double angle_threshold) {
-            return DetectEdgePoints(*pc, param, angle_threshold);
+            return DetectBoundaryPoints(*pc, param, angle_threshold);
         },
         py::arg("pc"),
         py::arg("param") = open3d::geometry::KDTreeSearchParamHybrid(0.01, 30),
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 6c8ffa4..97512b0 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -5,7 +5,7 @@ set(SRCS utils.cpp
          filter.cpp
          normal_estimation.cpp
          proximity_extraction.cpp
-         edge_detection.cpp
+         boundary_detection.cpp
          transform_estimation.cpp
          correspondence_matching.cpp
          ppf_estimation.cpp
diff --git a/src/edge_detection.cpp b/src/boundary_detection.cpp
similarity index 89%
rename from src/edge_detection.cpp
rename to src/boundary_detection.cpp
index 8f47b2c..55dcb6a 100644
--- a/src/edge_detection.cpp
+++ b/src/boundary_detection.cpp
@@ -1,4 +1,4 @@
-#include <misc3d/features/edge_detection.h>
+#include <misc3d/features/boundary_detection.h>
 #include <misc3d/logging.h>
 
 namespace misc3d {
@@ -59,14 +59,14 @@ bool IsBoundaryPoint(const open3d::geometry::PointCloud& pc,
         return false;
 }
 
-std::vector<size_t> DetectEdgePoints(
+std::vector<size_t> DetectBoundaryPoints(
     const open3d::geometry::PointCloud& pc,
     const open3d::geometry::KDTreeSearchParam& param, double angle_threshold) {
-    std::vector<size_t> edge_indices;
+    std::vector<size_t> boundary_indices;
     if (!pc.HasPoints()) {
         misc3d::LogError("No PointCloud data.");
         
-        return edge_indices;
+        return boundary_indices;
     }
 
     open3d::geometry::PointCloud pc_(pc);
@@ -94,14 +94,14 @@ std::vector<size_t> DetectEdgePoints(
         if (IsBoundaryPoint(pc_, pc_.points_[idx], ret_indices, u, v,
                             angle_threshold)) {
 #pragma omp critical
-            { edge_indices.push_back(idx); }
+            { boundary_indices.push_back(idx); }
         }
     }
 
-    misc3d::LogInfo("Found {} edge points from {} input points.",
-                             edge_indices.size(), num);
+    misc3d::LogInfo("Found {} boundary points from {} input points.",
+                             boundary_indices.size(), num);
 
-    return edge_indices;
+    return boundary_indices;
 }
 
 }  // namespace features
diff --git a/src/ppf_estimation.cpp b/src/ppf_estimation.cpp
index 9ab48d1..40c2f7c 100644
--- a/src/ppf_estimation.cpp
+++ b/src/ppf_estimation.cpp
@@ -11,7 +11,7 @@
 #include <stack>
 #include <unordered_map>
 
-#include <misc3d/features/edge_detection.h>
+#include <misc3d/features/boundary_detection.h>
 #include <misc3d/logging.h>
 #include <misc3d/pose_estimation/data_structure.h>
 #include <misc3d/pose_estimation/ppf_estimation.h>
@@ -1148,7 +1148,7 @@ void PPFEstimator::Impl::CalcModelNormalAndSampling(
 void PPFEstimator::Impl::ExtractEdges(const open3d::geometry::PointCloud &pc,
                                       double radius,
                                       std::vector<size_t> &edge_ind) {
-    edge_ind = features::DetectEdgePoints(
+    edge_ind = features::DetectBoundaryPoints(
         pc, open3d::geometry::KDTreeSearchParamHybrid(
                 radius, config_.edge_param_.pts_num));
 }