k-Wave

1. SHickling
   

   Member
   Joined: May '13
   Posts: 9

   Hello,

   I have an array of sensors that cannot be defined by a geometrical shape, so I have defined the sensor manually using a binary sensor mask. However, when I go to use time reversal reconstruction to reconstruct the image, I get the following error:

   In an assignment A(I) = B, the number of elements in B and I must be the
   same.
   Error in kspaceFirstOrder2D (line 747)
   p(sensor_mask_index) = sensor.time_reversal_boundary_data(:,t_index);

   My script works when I define a sensor using makeCartCircle, so I am wondering if it is not possible to use this reconstruction algorithm for a "non-standard" geometry?

   Thanks,
   Susannah

   Posted 10 years ago #

2. SHickling
   

   Member
   Joined: May '13
   Posts: 9

   Sorry never mind, my mistake!

   Posted 10 years ago #

3. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,640

   Glad you got it sorted!

   Posted 10 years ago #

4. Hamid
   

   Member
   Joined: Oct '13
   Posts: 3

   Hello,

   I generated some data using

   kspaceFirstOrder2D(kgrid, medium, source, sensor, input_args{:})

   Then I used the same function to reconstruct the image as follow:

   source.p0 = 0;
   sensor.time_reversal_boundary_data = sensor_data;
   p0_recon = kspaceFirstOrder2D(kgrid, medium, source, sensor, input_args{:});

   The following error message showed up:

   Error using kspaceFirstOrder_inputChecking (line 638)
   kgrid.t_array must be given explicitly in time reversal mode

   Thanks,
   Hamid

   Posted 9 years ago #

5. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,640

   Hi Hamid,

   For time reversal image reconstruction, the model needs to know the time step between the data points. This is specified using kgrid.t_array. For the forward simulation, if you leave this set to 'auto' (the default), the simulation code will automatically set this to something sensible. However, in the reconstruction, you must define this explicitly to match the forward problem (or experimental acquisition settings). There is some information on how to do this in Sec. 3.2 of the k-Wave User Manual.

   Brad.

   Posted 9 years ago #

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