From 90833606029ebedf1fdabe776c739c2ec11ceb86 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micka=C3=ABl=20Misbach?= <mickael@misba.ch>
Date: Fri, 7 Jul 2023 17:30:24 +0200
Subject: [PATCH] [mock_uss/riddp] Enforce min cluster size and fix obfuscation
 for NET0490 (#122)

* [mock_uss/riddp] Enforce min cluster size for NET0940

* add missing function

* make flow more explicit and readable

* apply both extends

* invert order offset-buffer; clarify flow

* add back missing condition

* fix randomization

* clarify implementation of cluster extensions

* add forgotten property decorator
---
 monitoring/mock_uss/riddp/clustering.py | 68 ++++++++++++++++++-------
 monitoring/monitorlib/rid.py            |  9 ++++
 2 files changed, 59 insertions(+), 18 deletions(-)

diff --git a/monitoring/mock_uss/riddp/clustering.py b/monitoring/mock_uss/riddp/clustering.py
index 298091c49f..e0f6ce8332 100644
--- a/monitoring/mock_uss/riddp/clustering.py
+++ b/monitoring/mock_uss/riddp/clustering.py
@@ -43,24 +43,58 @@ def randomize(self):
         v_min = min(p.y for p in self.points)
         u_max = max(p.x for p in self.points)
         v_max = max(p.y for p in self.points)
-        return Cluster(
-            x_min=self.x_min + (u_min - self.x_min) * random.random(),
-            y_min=self.y_min + (v_min - self.y_min) * random.random(),
-            x_max=u_max + (self.x_max - u_max) * random.random(),
-            y_max=v_max + (self.y_max - v_max) * random.random(),
-            points=self.points,
-        )
 
-    def extend_size(self, min_area_size: float):
-        scale = math.sqrt(min_area_size / self.area()) / 2
+        x_offset = random.uniform(-u_max, u_min)
+        y_offset = random.uniform(-v_max, v_min)
         return Cluster(
-            x_min=self.x_min - scale * self.width(),
-            x_max=self.x_max + scale * self.width(),
-            y_min=self.y_min - scale * self.height(),
-            y_max=self.y_max + scale * self.height(),
+            x_min=self.x_min + x_offset,
+            y_min=self.y_min + y_offset,
+            x_max=self.x_max + x_offset,
+            y_max=self.y_max + y_offset,
             points=self.points,
         )
 
+    def extend(self, rid_version: RIDVersion, view_area_sqm: float):
+        """Extend cluster size and dimensions to the minimum required"""
+
+        cluster = self
+
+        # Extend cluster width to match the minimum distance required by NET0490
+        if cluster.width() < 2 * rid_version.min_obfuscation_distance_m:
+            delta = rid_version.min_obfuscation_distance_m - cluster.width() / 2
+            cluster = Cluster(
+                x_min=cluster.x_min - delta,
+                x_max=cluster.x_max + delta,
+                y_min=cluster.y_min,
+                y_max=cluster.y_max,
+                points=cluster.points,
+            )
+
+        # Extend cluster height to match the minimum distance required by NET0490
+        if cluster.height() < 2 * rid_version.min_obfuscation_distance_m:
+            delta = rid_version.min_obfuscation_distance_m - cluster.height() / 2
+            cluster = Cluster(
+                x_min=cluster.x_min,
+                x_max=cluster.x_max,
+                y_min=cluster.y_min - delta,
+                y_max=cluster.y_max + delta,
+                points=cluster.points,
+            )
+
+        # Extend cluster to the minimum area size required by NET0480
+        min_cluster_area = view_area_sqm * rid_version.min_cluster_size_percent / 100
+        if self.area() < min_cluster_area:
+            scale = math.sqrt(min_cluster_area / self.area()) / 2
+            cluster = Cluster(
+                x_min=self.x_min - scale * self.width(),
+                x_max=self.x_max + scale * self.width(),
+                y_min=self.y_min - scale * self.height(),
+                y_max=self.y_max + scale * self.height(),
+                points=self.points,
+            )
+
+        return cluster
+
 
 def make_clusters(
     flights: List[observation_api.Flight],
@@ -94,15 +128,13 @@ def make_clusters(
 
     result: List[observation_api.Cluster] = []
     for cluster in clusters:
+        cluster = cluster.extend(rid_version, view_area_sqm)
+
+        # Offset cluster
         cluster = (
             cluster.randomize()
         )  # TODO: Set random seed according to view extents so a static view will have static cluster subdivisions
 
-        min_cluster_area = view_area_sqm * rid_version.min_cluster_size_percent / 100
-        if cluster.area() < min_cluster_area:
-            # Extend cluster to the minimum area size required by NET0480
-            cluster = cluster.extend_size(min_cluster_area)
-
         corners = LatLngRect(
             geo.unflatten(view_min, (cluster.x_min, cluster.y_min)),
             geo.unflatten(view_min, (cluster.x_max, cluster.y_max)),
diff --git a/monitoring/monitorlib/rid.py b/monitoring/monitorlib/rid.py
index ef3572adc2..24b889212d 100644
--- a/monitoring/monitorlib/rid.py
+++ b/monitoring/monitorlib/rid.py
@@ -91,6 +91,15 @@ def min_cluster_size_percent(self) -> float:
         else:
             raise ValueError("Unsupported RID version '{}'".format(self))
 
+    @property
+    def min_obfuscation_distance_m(self) -> float:
+        if self == RIDVersion.f3411_19:
+            return v19.constants.NetMinObfuscationDistanceM
+        elif self == RIDVersion.f3411_22a:
+            return v22a.constants.NetMinObfuscationDistanceM
+        else:
+            raise ValueError("Unsupported RID version '{}'".format(self))
+
     @property
     def short_name(self) -> str:
         if self == RIDVersion.f3411_19: