The DREAM (Discrete REpresentation Array Modeling) toolbox is a free open source toolbox for simulating acoustic fields radiated from common ultrasonic transducer types and arbitrarily complicated ultrasonic transducers arrays. The DREAM toolbox enables analysis of beam-steering, beam-focusing, and apodization for wideband (pulse) excitation both in near and far fields.
The DREAM toolbox can be used to, for example, simulate and evaluate array designs, evaluate imaging methods etc. An example is shown in Figure 1 below where the wavefield of an (undersampled) 32 element linear array has been simulated.
Figure 1. Simulated wavefield snapshot for a 32 element linear array.
The toolbox consists of a set of routines for computing (discrete) spatial impulse responses (SIRs) for various single-element transducer geometries as well as multi-element transducer arrays. Based on linear systems theory, these SIR functions can then be convolved with the transducer's electrical impulse response to obtain the acoustic field at an observation point. By using the DREAM toolbox one can simulate ultrasonic measurement systems for many configurations including phased arrays and measurements performed in lossy media.
The DREAM toolbox uses a numerical procedure based on based on the discrete representation (DR) computational concept [[1],[2]] which is a method based on the general approach of the spatial impulse responses [[3],[4]].
The DREAM Toolbox can be used using:
- Matlab and Octave,
- Python (experimental),
- Julia (experimental, only tested on Linux),
- Computes spatial impulse responses (SIRs) directly in a discrete form,
- Support for many common transducer and array types,
- Support for parallel processing using threads (and on the GPU on select functions),
- Compute SIRs for lossy media,
- Accelerated delay-and-sum (DAS) synthetic aperture imaging beamforming (SAFT, TFM and row-column adressed [RCA] array DAS).
There is a PDF version of the user manual for each release available here:
https://github.com/frli8848/DREAM/releases
Look under Assets for the corresponding release.
| Function | Description | MATLAB | Octave | Python | Julia |
|---|---|---|---|---|---|
| dreamline | Strip/line transducer | Yes | Yes | Yes | Yes |
| dreamrect | Rectangular transducer | Yes | Yes (*) | Yes | Yes |
| dreamrect_f | Focused rectangular transducer | Yes | Yes | Yes | Yes |
| dreamcirc | Circular transducer | Yes | Yes (*) | Yes | Yes |
| dreamcirc_f | Focused circular transducer | Yes | Yes | Yes | Yes |
| dreamsphere | Spherical concave/convex transducer (defocused/defocused) | Yes | Yes | Yes | Yes |
| dreamcylind | Cylindrical concave/convex transducer (focused/defocused) | Yes | Yes | Yes | Yes |
| dream_arr_rect | Array with rectangular elements | Yes | Yes | Yes | Yes |
| dream_arr_circ | Array with circular elements | Yes | Yes | Yes | Yes |
| dream_arr_cylind | Array with cylindrical concave/convex elements (focused/defocused) | Yes | Yes | Yes | Yes |
| dream_arr_annu | Annular array | Yes | Yes | Yes | Yes |
Table 1. DR-based transducer functions.
| Function | Description | MATLAB | Octave | Python | Julia |
|---|---|---|---|---|---|
| rect_sir | time-continous (analytic) rectangual ransducer | Yes | Yes (*) | N/A | N/A |
| circ_sir | time-continous (analytic) circular ransducer | Yes | Yes | N/A | N/A |
| scirc_sir | sampled time-continous (analytic) circular transducer | Yes | Yes | N/A | N/A |
Table 2. Analytic transducer functions.
| Function | Description | MATLAB | Octave | Python | Julia |
|---|---|---|---|---|---|
| conv_p | threaded one dimensional convolution | Yes | Yes | N/A | N/A |
| fftconv_p | threaded one dimensional FFT based convolutions | Yes | Yes | N/A | N/A |
| fftconv_ola | threaded one dimensional FFT based convolutions using overlap-and-add | Yes | Yes | N/A | N/A |
| sum_fftconv | threaded sum of one dimensional FFT based convolutions | Yes | Yes | N/A | N/A |
| das | threaded delay-and-sum (DAS) beamforming (SAFT, TFM, and RCA) | Yes (*) | Yes (*) | N/A | N/A |
| das_uni | (OpenCL only) DAS beamforming using uniform grids (SAFT, TFM, and RCA) | Yes (*) | Yes (*) | N/A | N/A |
Table 3. Threaded (parallel) signal processing algorithms.
(*) Experimental GPU support (OpenCL).
See also known issues here.
[1] B.Piwakowski and B. Delannoy. "Method for Computing Spatial Pulse Response: Time-domain Approach", Journal of the Acoustical Society of America, vol. 86, no. 6, pp. 2422--32, Dec. 1989.
[2] B. Piwakowski and K. Sbai. "A New Approach to Calculate the Field Radiated from Arbitrarily Structured Transducer Arrays", IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, vol. 46, no. 2, pp. 422--40, March 1999.
[3] G. E. Tupholme, "Generation of acoustic pulses by baffled plane pistons", Mathematika, vol 16, pp. 209--224, 1969.
[4] P.R. Stepanishen. "Transient radiation from pistons in an infinite planar baffle", Journal of the Acoustical Society of America, vol 49, pp. 1629--38, 1971.
See the installation instructions here.