[Positioner] New option filter.cp-reset-distance

The new option positioning.filter.cp-reset-distance allows to disable
the filter when the unfiltered location of the mobile terminal is found
to be close enough to a capture point.

owlps-positioner/cfg/owlps-positioner.conf

@@ -257,6 +257,16 @@ mobile-csv-file = /usr/local/etc/owlps/mobiles.csv
 # This option also controls the activation of the filter (0 = disabled).
 #max-speed = 0
 
+# With this option set to a positive number, the filtering is temporary
+# disabled when the mobile terminal is found to be close enough to a
+# capture point. This option determines this "close enough" distance, in
+# metres.
+# This is useful in deployments where the system is much more accurate
+# when the mobile is close to a capture point, such as underground
+# mining tunnels; in such environments, 15 m appears to be a reasonable
+# value to start experimenting.
+#cp-reset-distance = 0
+
 [output]
 # The following options are related to the output of the results.
 

owlps-positioner/positioning.cc

@@ -194,34 +194,63 @@ void Positioning::loop()
  */
 void Positioning::filter(const Request &request, Result &result)
 {
-  // Don't apply filter if filtering is disabled
+  /* Don't apply filter if filtering is disabled */
   float max_speed =
     Configuration::float_value("positioning.filter.max-speed") ;
   if (max_speed <= 0)
     return ;
 
-  // Don't apply filter if it is the first result we compute for this
-  // mobile (hence we don't have previous results to compare to)
+  /* Don't apply filter if it is the first result we compute for this
+   * mobile (hence we don't have previous results to compare to) */
   const Mobile *const mobile = request.get_mobile() ;
   const ResultList &last_results = mobile->get_last_results() ;
   if(last_results.empty())
     return ;
 
-  // Don't apply filter if the "algorithm" is the real position
+  /* Don't apply filter if the "algorithm" is the real position */
   string algo_name = result.get_algorithm() ;
   if (algo_name == "Real")
     return ;
 
+  /* Print the common message in verbose mode */
+  const Timestamp &timestamp = result.get_request()->get_time_sent() ;
+  if (Configuration::is_configured("verbose"))
+    cerr
+        << "Filtering (algorithm " << algo_name << "): "
+        << "for request sent at " << timestamp
+        << " by mobile " << mobile->get_mac_addr() << ", " ;
+
+  /* Don't apply filter if the reset distance is configured and the
+   * mobile is within this distance */
+  // Get the unfiltered coordinates:
+  const Point3D &pos = result.get_position() ;
+  float reset_distance =
+    Configuration::float_value("positioning.filter.cp-reset-distance") ;
+  if (reset_distance > 0)
+    {
+      float dist_closest_cp = Stock::distance_from_closest_cp(pos) ;
+      assert(dist_closest_cp >= 0) ;
+      if (dist_closest_cp <= reset_distance)
+        {
+          if (Configuration::is_configured("verbose"))
+            cerr
+                << "the mobile appears to be within the reset distance"
+                << " of " << reset_distance
+                << " m from a CP; no filtering.\n" ;
+          return ;
+        }
+    }
+
+  /* Okay, now let's get to it! */
+
   const Result &prev_result = last_results.get_result_for_algo(algo_name) ;
 
   // Calculate the travel time (duration)
-  const Timestamp &timestamp = result.get_request()->get_time_sent() ;
   const Timestamp &prev_timestamp =
     last_results.get_request()->get_time_sent() ;
   Timestamp duration = prev_timestamp.elapsed(timestamp) ;
 
-  // Get the current and previous coordinates
-  const Point3D &pos = result.get_position() ;
+  // Get the previous coordinates
   const Point3D &prev_pos = prev_result.get_position() ;
 
   // Recompute the result by interpolation
@@ -229,13 +258,9 @@ void Positioning::filter(const Request &request, Result &result)
   if (filtered_pos != pos)
     {
       if (Configuration::is_configured("verbose"))
-        cerr
-            << "Filtering (algorithm " << algo_name << "): "
-            << "for request sent at " << timestamp
-            << " by mobile " << mobile->get_mac_addr()
-            << ", " << pos
-            << " was replaced by " << filtered_pos
-            << ".\n" ;
+        cerr << pos << " was replaced by " << filtered_pos << ".\n" ;
       result.set_position(filtered_pos) ;
     }
+  else if (Configuration::is_configured("verbose"))
+    cerr << "the original position looked good enough and was kept.\n" ;
 }

owlps-positioner/userinterface.cc

@@ -332,6 +332,10 @@ void UserInterface::fill_positioning_options()
    po::value<float>()->default_value(0),
    "Maximal speed at which the mobiles can move, in km/h (0 = unlimited"
    " speed).")
+  ("positioning.filter.cp-reset-distance",
+   po::value<float>()->default_value(0),
+   "Disable filtering when the computed position is at this distance (in"
+   " m) from a CP or closer (0 = never disable filtering).")
   ;
 
   file_options->add(options) ;