node-natnet

A client for the Optitrack NatNet client in Node.js. The implementation uses the official NatNetSDK. Using this module it is possible the gather frame data from the Motive software by enabling Data Streaming in it.

Usage

const { NatNetClient } = require('node-natnet')

const client = new NatNetClient()

client.initialize({
  local: '127.0.0.1',
  server: '127.0.0.1'
})

client.on('frame', data => {
  console.log('Received frame data: ', data)
})

Install

Install from NPM:

$ npm install node-natnet

Install from the Git repository:

$ git clone https://github.com/gerhardberger/node-natnet.git
$ cd node-natnet
$ npm install

Then in your code import it with its path: require('path/to/folder').

Compiling manually

The module comes with prebuilt binaries for various Node.js versions, but if your's not supported, you can compile it manually, by running npm run compile inside the node-natnet folder after npm install.

API Reference

Methods

const client = new NatNetClient(type)

Creates a new NatNetClient instance. type is an optional String parameter that determines the connection (this can be configured inside Motive).

The possible connection types are:

• 'unicast', default
• 'multicast'.

client.initialize(options)

Initializes and connects to a NatNet server that can be started in Motive.

The options object can contain:

• local: String, the local IP address that the client is running on. Required.
• server: String, the server IP address that the data is streamed to. Required.
• hostCommandPort: Number, the custom command port if there is one. Optional.
• hostDataPort: Number, the custom data port if there is one. Optional.

client.uninitialize()

Disconnects the client application from the server.

Events

client.on('frame', callback)

This event is emitted every time there is new frame data received from Motive. The rate of this is dependent on the FPS counter in Motive.

The callback has one parameter which is an object containing the current frame data:

• id: The current frame identifier.
• markerSets: A named collection of identified markers and the marker positions { x, y, z }.
• otherMarkers: List of point cloud solved 3D positions { x, y, z } for all markers in the frame that are not labeled.
• labeledMarkers: Ordered, padded, point cloud solved, model filled (where occluded) labeled marker data.
• latency: The latency value of the frame.
• timestamp: Timing information for the frame.

Properties

client.connected

A Boolean value that indicates wether the client is connected to the server.

client.serverDescription

Fetches the server description through a NatNet command. Returns an Object:

• hostPresent: Boolean
• hostComputerName: String
• hostComputerAddress: String
• hostApp: String
• appVersion: String
• natNetVersion: String

client.dataDescriptions

Fetches the data descriptions through a NatNet command. Returns an [Object]:

• name: String
• markerNames: String