Use smaller range for U-turn angles in map-matching

Author: oxidase

CHANGELOG.md

@@ -1,3 +1,8 @@
+# 5.16.2
+  - Changes from 5.16.1:
+    - Bugfixes:
+      - FIXED #4920: Use smaller range for U-turn angles in map-matching [#4920](https://github.com/Project-OSRM/osrm-backend/pull/4920)
+
 # 5.16.1
   - Changes from 5.16.0:
     - Bugfixes

features/step_definitions/matching.js

@@ -74,7 +74,7 @@ module.exports = function () {
 
                         if (headers.has('turns')) {
                             if (json.matchings.length != 1) throw new Error('*** Checking turns only supported for matchings with one subtrace');
-                            turns = this.turnList(json.matchings[0].instructions);
+                            turns = this.turnList(json.matchings[0]);
                         }
 
                         if (headers.has('route')) {

features/testbot/matching.feature

@@ -684,3 +684,34 @@ Feature: Basic Map Matching
         When I match I should get
           | trace | geometry                                      | code |
           | bgkj  | 1.000135,1,1.000135,0.99964,1.000387,0.999137 | Ok   |
+
+
+    @match @testbot
+    Scenario: Regression test - waypoints trimming too much geometry
+        Given the profile "testbot"
+        Given a grid size of 10 meters
+        Given the query options
+          | geometries | geojson |
+        Given the node map
+          """
+                e
+                ;
+                ;
+          a-----b-----c
+                ;
+                ;
+                d
+          """
+        And the ways
+          | nodes |
+          | abc   |
+          | bde   |
+        Given the query options
+          | waypoints | 0;2  |
+          | overview  | full |
+          | steps     | true |
+        When I match I should get
+          | trace | geometry                                   | turns                    | code |
+          | abc   | 1,0.99973,1.00027,0.99973,1.000539,0.99973 | depart,arrive            | Ok   |
+          | abd   | 1,0.99973,1.00027,0.99973,1.00027,0.999461 | depart,turn right,arrive | Ok   |
+          | abe   | 1,0.99973,1.00027,0.99973,1.00027,1        | depart,turn left,arrive  | Ok   |

include/engine/guidance/assemble_geometry.hpp

@@ -80,7 +80,9 @@ inline LegGeometry assembleGeometry(const datafacade::BaseDataFacade &facade,
         prev_coordinate = coordinate;
 
         const auto osm_node_id = facade.GetOSMNodeIDOfNode(path_point.turn_via_node);
-        if (osm_node_id != geometry.osm_node_ids.back())
+
+        if (osm_node_id != geometry.osm_node_ids.back() ||
+            path_point.turn_instruction.type != osrm::guidance::TurnType::NoTurn)
         {
             geometry.annotations.emplace_back(LegGeometry::Annotation{
                 current_distance,

src/engine/plugins/match.cpp

@@ -44,7 +44,7 @@ void filterCandidates(const std::vector<util::Coordinate> &coordinates,
                                                            coordinates[current_coordinate + 1]);
 
             // sharp turns indicate a possible uturn
-            if (turn_angle <= 90.0 || turn_angle >= 270.0)
+            if (turn_angle <= 45.0 || turn_angle >= 315.0)
             {
                 allow_uturn = true;
             }