UX basically working

lib/models/osm_camera_node.dart

@@ -11,6 +11,27 @@ class OsmCameraNode {
     required this.tags,
   });
 
+  Map<String, dynamic> toJson() => {
+    'id': id,
+    'lat': coord.latitude,
+    'lon': coord.longitude,
+    'tags': tags,
+  };
+
+  factory OsmCameraNode.fromJson(Map<String, dynamic> json) {
+    final tags = <String, String>{};
+    if (json['tags'] != null) {
+      (json['tags'] as Map<String, dynamic>).forEach((k, v) {
+        tags[k.toString()] = v.toString();
+      });
+    }
+    return OsmCameraNode(
+      id: json['id'] is int ? json['id'] as int : int.tryParse(json['id'].toString()) ?? 0,
+      coord: LatLng((json['lat'] as num).toDouble(), (json['lon'] as num).toDouble()),
+      tags: tags,
+    );
+  }
+
   bool get hasDirection =>
       tags.containsKey('direction') || tags.containsKey('camera:direction');