Wrong values in a custom message

[Arttii]

Hi,

I am trying to publish a custom message type and consume it with foxglove/foxglove bridge. I generated a definition from this https://github.com/foxglove/schemas/blob/main/schemas/ros1/LocationFix.msg. And it seems correct to me:

const (
	LocationFix_UNKNOWN        uint8 = 0
	LocationFix_APPROXIMATED   uint8 = 1
	LocationFix_DIAGONAL_KNOWN uint8 = 2
	LocationFix_KNOWN          uint8 = 3
)

type LocationFix struct {
	msg.Package            `ros:"foxglove_msgs"`
	msg.Definitions        `ros:"uint8 UNKNOWN=0,uint8 APPROXIMATED=1,uint8 DIAGONAL_KNOWN=2,uint8 KNOWN=3"`
	Timestamp              time.Time
	FrameId                string
	Latitude               float64
	Longitude              float64
	Altitude               float64
	PositionCovariance     [9]float64
	PositionCovarianceType uint8
}

I am publishing it like this:

u.rosPub.Write(&LocationFix{

					Latitude:               p.Latitude,
					FrameId:                "gps",
					Timestamp:              time.Now(),
					Longitude:              p.Longitude,
					Altitude:               1,
					PositionCovariance:     [9]float64{},
					PositionCovarianceType: LocationFix_APPROXIMATED,
					// Timestamp:              time.Now(),

				})

The problem is, that the message arrives but has incorrect values. For example, it assigns the 1 to Longitude instead of Altitude and some fields are not sent at all. Here is an example:

{
  "latitude": 1.4392584190017515e-71,
  "longitude": 1.1242743746318638e+224,
  "altitude": -2.2312966463100733e-47,
  "position_covariance": [
    1.804875673222033e-307,
    1.7765824089018436e-307,
    0,
    0,
    0,
    0,
    0,
    0,
    0
  ],
  "position_covariance_type": 0
}

It seems there are some kinds of precision issues here? I would appreciate any help. Thanks!

[aler9]

Hello, i tested the code you provided against foxglove-bridge but i found no issues at all. This is the foxglove-based subscriber that i used to perform the test:

const { FoxgloveClient } = require("@foxglove/ws-protocol");
const { parse } = require("@foxglove/rosmsg");
const { MessageReader } = require("@foxglove/rosmsg-serialization");
const { WebSocket } = require("ws");

const def0 = `# foxglove_msgs/LocationFix
# A navigation satellite fix for any Global Navigation Satellite System

# Generated by https://github.com/foxglove/schemas

# Timestamp of the message
time timestamp

# Frame for the sensor. Latitude and longitude readings are at the origin of the frame.
string frame_id

# Latitude in degrees
float64 latitude

# Longitude in degrees
float64 longitude

# Altitude in meters
float64 altitude

# Position covariance (m^2) defined relative to a tangential plane through the reported position. The components are East, North, and Up (ENU), in row-major order.
float64[9] position_covariance

uint8 UNKNOWN=0
uint8 APPROXIMATED=1
uint8 DIAGONAL_KNOWN=2
uint8 KNOWN=3

# If \`position_covariance\` is available, \`position_covariance_type\` must be set to indicate the type of covariance.
uint8 position_covariance_type
`;

async function main() {
  const client = new FoxgloveClient({
    ws: new WebSocket(`ws://localhost:8765`, [FoxgloveClient.SUPPORTED_SUBPROTOCOL]),
  });

  let reader = null;

  client.on("advertise", (channels) => {
    for (const channel of channels) {
      if (channel.topic !== "/test_topic") {
        continue;
      }

      console.log("subscribing");
      client.subscribe(channel.id);
      reader = new MessageReader(parse(def0));
    }
  });

  client.on("message", ({ subscriptionId, timestamp, data }) => {
    const message = reader.readMessage(data);

    console.log({
      subscriptionId,
      timestamp,
      message,
    });
  });
}

main().catch(console.error);

output:

{
  subscriptionId: 0,
  timestamp: 1688590295787619606n,
  message: Record {
    timestamp: { sec: 1688590295, nsec: 787409259 },
    frame_id: 'gps',
    latitude: 123,
    longitude: 456,
    altitude: 1,
    position_covariance: Float64Array(9) [
      0, 0, 0, 0, 0,
      0, 0, 0, 0
    ],
    position_covariance_type: 1
  }
}

Make sure that the message definition is the same on both sides and that you are using @foxglove/rosmsg-serialization to deserialize messages.