Atmospheric Ray Tracing

An efficient, open-source framework for finding eigenrays in a stratified, moving medium

Overview

The Atmospheric Ray Tracing (ART) framework allows to simulate curved sound propagation through an three-dimensional, inhomogeneous, moving atmosphere. The atmosphere is assumed to be stratified meaning the weather parameters are only altitude-dependent and wind direction is purely horizontal. In addition to predefined analytic models, arbitrary data vectors can be used for the weather data (e.g. from atmospheric soundings). In accordance to this stratified model, the ground is assumed to be flat.

Visualization of eigenrays of an aircraft flyover during take-off

The framework is designed for the purpose of aircraft noise auralization. Thus, in addition to tracing rays into defined directions, it provides an efficient method for finding eigenrays connecting a source with a receiver. This approach is called adaptive ray zooming. The methods used in this framework are well documented in this open-access publication.

Being part of the ITAGeometricalAcoustics C++ library collection, the framework is open-source. The code is provided on the respective git repository. The ART framework can be interfaced in Matlab using the ARTMatlab application. It allows a visualization of the simulated sound paths and derivation of acoustic parameters based on those paths.


ARTMatlab

The MEX file application to interface the Atmospheric Ray Tracing (ART) framework via Matlab

Getting started

ARTMatlab is a MEX file application including the Atmospheric Ray Tracing framework. It contains a set of classes allowing to interface the ART framework fast and easily. In addition to the simulation of rays and eigenrays, it also provides methods to derive acoustic parameters based on those sound paths.

Requirements

The ITA-Toolbox for Matlab must be installed before ARTMatlab can be used.

Matlab classes
Class name Description
AtmosphericRayTracer The interface to the simulation engine and can either be used to trace rays into given directions or to find eigenrays.
StratifiedAtmosphere Allows to configure the weather parameters, such as temperature, wind velocity/direction and relative humidity of the medium. It is able to import data from atmospheric soundings.
AtmosphericRay Represents one of the resulting sound paths. The class comes with convenience functions e.g. for plotting
AtmosphericPropagation Allows to derive acoustic parameters or to generate a transfer function based on a set of eigenrays

Tutorials
Check out the tutorial scripts provided in the main folder of ARTMatlab to get some examples of how to use the framework:
  • ARTTutorial_Overview.m
  • ARTTutorial_StratifiedAtmosphere.m
  • ARTTutorial_PropagationModel.m

Download

Name Version Changes
ARTMatlab_v2021b v2021b Newest release. Added PropagationModel class. Eigenrays now have a property indicating whether receiver sphere was hit. AtmosphericRayTracer class now can display ARTMatlab version.
ARTMatlab_v2021a v2021a Initial release used in the paper introducing the framework.

Auralization

Based on the ART framework and Virtual Acoustics (VA)

Auralization of an aircraft flyover during take-off based on the ART framework

Changing the wind direction during aircraft flyover auralization - High quality visual model (IHTAPark)


Scientific publications

P. Schäfer and M. Vorländer
Atmospheric Ray Tracing: An efficient, open-source framework for finding eigenrays in a stratified, moving medium
Acta Acustica, Volume 5, 2021
https://doi.org/10.1051/aacus/2021018