The realtime_zshimming.m script uses a time series of B0 maps to compute the static and dynamic shim gradients that are needed for z-shimming. If z-shimming is going to be done with a gradient echo scan, then realtime_zshimming.m requires a sample magnitude gradient echo scan so that the static and dynamic shim gradient images can be resampled to the resolution of the gradient echo scan.

"realtime_zshim.m" calls resliceimg here:
https://github.com/shimming-toolbox/shimming-toolbox/blob/9081cdac6701d7df74c5db109c205655be10d54e/example/realtime_zshim.m#L310

Instead of doing realtime z-shimming with a gradient echo scan, I am attempting to do it with an EPI scan. This means that realtime_zshimming.m will use an EPI scan to resample the static and dynamic shim gradient maps to the resolution of EPI scan. When trying this, I run into the following error:

Index exceeds the number of array elements (68992).

Error in MaRdI/resliceimg (line 1342)
            [~,iNearest(iR)] = min( sqrt( ( X_Ip - X_Ep( iEp(iR) ) ).^2 + ...

Error in realtime_zshim (line 310)
GzField.resliceimg( X,Y,Z, mask ) ; % reslice static b0 image

There is sample data to test this out here. The realtime_zshim.m script can be called using realtime_zshim('phantom') in the folder containing the sample data. You will then be prompted to enter the paths of the B0 maps and the EPI (or GRE) images.