http://www.k-wave.org/forum/topic/about-sensors-and-focus-in-the-matlab-example-example_ewp_3d_simulationm Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 03:45:40 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/about-sensors-and-focus-in-the-matlab-example-example_ewp_3d_simulationm#post-5645 Fri, 19 Aug 2016 21:57:51 +0000 uhultrasound 5645@http://www.k-wave.org/forum/ <p>Hi Brad,</p> <p>Thank you very much and have a good weekend.</p> <p>John </p> http://www.k-wave.org/forum/topic/about-sensors-and-focus-in-the-matlab-example-example_ewp_3d_simulationm#post-5631 Wed, 10 Aug 2016 17:18:31 +0000 Bradley Treeby 5631@http://www.k-wave.org/forum/ <p>Hi John,</p> <p>To understand the different ways the sensor mask can be defined (and how it is indexed), I would suggest working through the first few examples under the "Initial Value Problems" heading in the k-Wave help (this can be accessed through the MATLAB help browser as described in the manual). To change what is recorded, you need to modify the value of <code>sensor.record</code>. For more details, see the "Recording The Particle Velocity Example" or the k-Wave manual. </p> <p>For this particular example, the source is a velocity source. Thus without focusing, each source element propagates as a point dipole (rather than a point monopole which would emit a spherical wave). See the first two examples under the "Time Varying Source Problems" heading for more details of the field shape. If you want to create a monopole source, you could instead define the normal components of the stress.</p> <p>Hope that helps,</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/about-sensors-and-focus-in-the-matlab-example-example_ewp_3d_simulationm#post-5617 Fri, 29 Jul 2016 14:53:04 +0000 uhultrasound 5617@http://www.k-wave.org/forum/ <p>Hi,</p> <p>I tested the program further. It seems the sensor mask is a rectangular mask. So, it seems the final output graph is not a graph of sensor position vs. time, but it is a graph of the recorded maximum pressure map of X-axis vs. Y-axis (there is no time information), am I right? If so, I was wondering if you could please help let me know how to save data of the pressure vs. time for the sensor mask in example_ewp_3D_simulation.m?</p> <p>In addition, it seems when I removed the "source.ux = focus(kgrid, source.ux, source.u_mask, [0, 0, 0], 1500);" code, the ultrasound wave will propagate in media as spherical waves.</p> <p>Many thanks,</p> <p>John </p> http://www.k-wave.org/forum/topic/about-sensors-and-focus-in-the-matlab-example-example_ewp_3d_simulationm#post-5615 Wed, 27 Jul 2016 23:16:12 +0000 uhultrasound 5615@http://www.k-wave.org/forum/ <p>Hi,</p> <p>Thank you very much for sharing the wonderful program. I am testing the Matlab example example_ewp_3D_simulation.m. Since I can't figure out what the sensors' positions are and how many sensors there are, I don't quite understand the final output graph of sensor position vs. time. I was wondering if you please help me with the following questions:</p> <p>1. What the sensors' positions are and how many sensors there are? I don't quite follow "define sensor mask in x-y plane using cuboid corners, where a rectangular mask is defined using the xyz coordinates of two opposing corners in the form [x1, y1, z1, x2, y2, z2]." Is it a rectangular sensor 2D-array? Then, how to index the 2D-array sensors?</p> <p>2. May I visualize the sensors by using voxelPlot function? I tried "voxelPlot(double(cart2grid(kgrid, sensor.mask)));", but it doesn't work.</p> <p>3. For ultrasound focusing, I was wondering if I could assume the ultrasound wave propagates in media as spherical waves without focusing? May I do this in example_ewp_3D_simulation.m?</p> <p>Many thanks and have a great day.</p> <p>John </p>