Tile38 Experiment

Hypothesis:

We know that in a Tile38 geofencing system, any position requires at least two spatial dimensions X,Y (latitude,longitude) to be defined (haversine formula). The third coordinate Z is reserved for elevation(3rd spatial dimension), zoom-in/out operations and other application-specific purposes,provided it is expressed in integer or float numbers. In addition, Time is also a dimension, although temporal instead of spatial , it can still be measured and expressed in R numbers. So, it seems intuitively probable that the server, although understands integers and floats, it is completely “blind” to the concepts of Space and Time and even though Z constitutes a numerical expression of time, it would still take it into consideration in the interaction between tile38 objects. But we also know that a geofence calculates only spatial X,Y properties of an object in order to determine it’s (new) position and transmit the proper Webhook event.

Assertion:

The hypothesis is that webhook emits events regardless of Z property, as long as the fence does not filter against Z.

We need to figure:

1. If a geofence is aware of any object points that have a Unix timestamp at Z.

   Result: positive / negative

   types of event to consider: any

2. Which events* are emitted from geofence webhook upon detection of object on each case: a) with Z timestamp . b) without Z timestamp .

   Result: Same / Different

   types of event to consider: cross,enter,inside,exit

3. What types of events* are emitted from geofence webhook upon detection of object that is filtered against Z property:

   a) with timestamp in accepted range.

   b) With Z timestamp out of accepted range

   types of event to consider: cross,enter,inside,exit

Experiment:

First test:

1. The following geofence is set:

   SETHOOK zone {endpoint} INTERSECTS fleet FENCE DETECT enter ,exit ,inside,cross
   OBJECT {athens_dactylios.geojson}
   

2. Move fleet object to the predefined points to yield any detection.

3. Log results from endpoint.

4. Expected results: geofence to be aware

5. Reset enviroment: drop fleet & pdelhook *

Second test

1. The geofence is set :

   SETHOOK zone {endpoint} INTERSECTS fleet FENCE DETECT enter ,exit           ,inside,cross
   OBJECT {athens_dactylios.geojson}
   

2. Move fleet object to points to yield any detection.

   SET fleet scooter POINT lat lon
   

3. Log results from endpoint.

4. Move object to points to yield any detection.

   SET fleet scooter POINT lat lon timestamp
   

5. Log results from endpoint.

6. Expected results: Results same.

7. Reset enviroment: drop fleet & pdelhook *

Third test

1. The geofence is set :

   SETHOOK zone {endpoint} INTERSECTS fleet FENCE DETECT enter ,exit ,inside,cross
   WHERE z timestamp +inf OBJECT {athens_dactylios.geojson}
   

2. Move object to points as in point_movement.geojson to yield any detection.

   SET fleet scooter POINT lat lon timestamp
   

3. Log the results.

4. Reset enviroment: drop fleet & pdelhook *

5. The geofence is re-set :

   SETHOOK zone_athens_dactylios {endpoint} INTERSECTS fleet FENCE DETECT
   enter ,exit ,inside,cross WHERE z -inf timestamp OBJECT  {athens_dactylios.geojson}
   

6. Move object to points to yield detections.

   SET fleet scooter POINT lat lon timestamp
   

7. Log the results.

8. Expected results: Results between the two tests will be different. JSON file for key points : point_movement.geojson JSON file for fence: athens_dactylios.geojson

   Results as shown in log texts:

   • Test 1

     • log_test_1_case_1.txt Success : Webhook is aware of objects that include timestamp at Z property

   • Test 2

     • log_test_2_case_1.txt
     • log_test_2_case_2.txt
     • Success : Webhook emits same events between objects that have a timestamp Z and those without.

   • Test 3

     • log_test_2_case_1.txt
     • log_test_2_case_1.txt Success : Webhook emits different results when objects are filtered against Z property and are out of time range.

CONCLUSION:

In response to the initial question of the assignment, the answer is that indeed Webhooks are completely aware of all the objects of a given collection that are set to observe, regardless of wether the objects have a Z property or not.

However, when using a filter against Z , then the results are very different.

Objects that move either beyond the spatial boundaries X,Y or the temporal boundaries of Z trigger events, yet are detected as being outside of the geofence.

PYTHON DOCUMENTATION

Commands:

$ python3 -i dispatch.py

• usage: Enviroment [-u URL] [-p PORT] [-d] options:
  • -u [HOST], --url [HOST] server uri
  • -p [PORT], --port [PORT] server port : integer
  • -d, --defaults Enable default objects

2. Console:

   • main = Enviroment( )

     • name = str
   1. Webhook

   • webhook = main.build_webhook(name=”test”) #(instantiated Webhook class)

     • params:
       • name : str
       • path = “filepath” ( optional)

   • .deploy_webhook()

     • params: name
       • trigger : Optional. automatic initially with defaults (enter,exit,inside,cross)
       • timeLow: str or int = 0 distance from lowest filtering value- optional
       • timeHi :str or int = 60 distance from highest filtering value- optional

   • .kill_webhook()

     • params:
       • all:bool = False if all == True →deletes all webhooks else deletes self

   • .set_triggers( )

     • params:
       • trigger = list of strings of detection triggers
   2. Fleet

      • scooter = main.build_fleet()

        • name = required
        • filepath of geoJson point object

      • .create_steps(interval =0) builds Generator object that returns points one by one

        • interval : optional integer. time difference from timestamp in seconds. plus/ minus

      • .run_step() generator - yields XY point and executes it in tile38 server

      • .run_sequence() iterates the generator and executes all movements at once

      • .drop_fleet( ) drops current object from server

Technologies used:

• Python 3.10.7
• Django rest framework as a basic oversimplified endpoint
• vector.rocks
• PyCharm

C) DJANGO CODE

import json
class webhook(GenericViewSet, CreateModelMixin):
        permission_classes = [AllowAny]
        def create(self, request, *args, **kwargs):
             
                ##get items from JSON#
                payload =json.loads(request.body)
                log_detect= payload('detect')log_time =payload('time')
                log_id =payload.get('id')
                log_coords = payload.get('object').get('coordinates')
                log_key = payload.get('key')
                file =f"log_{log_key}_{log_id}.txt"
                path = pathlib.Path(f"python_tile38_assign/test_cases/{file}")
                path.parent.mkdir(parents=True, exist_ok=True)
                path = path.resolve()
                print(payload,log_detect )
                list = [ 
                       log_detect,
                        log_time,
                         log_coords,
                          log_id,
                            log_key,]
                 _list= " : ".join([str(item) for item in _list])
                 with path.open ("a+") as f:
                         f.write(_list + "\n")
                 return Response(status=200)