GPS Schema Example

Topic: /gps
Message: NavSatFix

This example will go through how to connect to the GPS topic published on your EdgeFirst Platform and how to display the information through the Rerun visualizer.

Setting up subscriber

After setting up the Zenoh session, we will create a subscriber to the rt/gps topic

PythonRust

# Create a subscriber for "rt/gps"
loop = asyncio.get_running_loop()
drain = MessageDrain(loop)
session.declare_subscriber('rt/gps', drain.callback)

let subscriber = session
    .declare_subscriber("rt/gps")
    .await
    .unwrap();

Receive the Message

We can now receive a message on the subscriber. After receiving the message, we will set it up for processing.

PythonRust

async def gps_handler(drain):
    while True:
        msg = await drain.get_latest()
        thread = threading.Thread(target=gps_worker, args=[msg])
        thread.start()

        while thread.is_alive():
            await asyncio.sleep(0.001)
        thread.join()

use edgefirst_schemas::sensor_msgs::{NavSatFix};
msg = subscriber.recv()
let gps: NavSatFix = cdr::deserialize(&msg.payload().to_bytes())?;

Process the GPS Data

We will now pull out the latitude/longitude data from the decoded NavSatFix message and log the data to Rerun.

PythonRust

def gps_worker(msg):
    gps = NavSatFix.deserialize(msg.payload.to_bytes())
    rr.log("CurrentLoc",
            rr.GeoPoints(lat_lon=[gps.latitude, gps.longitude]))

let lat = gps.latitude;
let long = gps.longitude;
// println!("Latitude: {} Longitude: {}",lat, long);
let _ = rec.log("CurrentLoc", &rerun::GeoPoints::from_lat_lon([(lat, long)]));

Results

The command line output will appear as the following

Latitude: 51.036506 Longitude: -114.034886
Latitude: 51.036506 Longitude: -114.034886
Latitude: 51.036506 Longitude: -114.034886

When displaying the results through Rerun you will see a map with the location of your EdgeFirst Platform marked. alt text