3dMVM error in dim

Dear AFNI,

How do I find out whether my images are in different orientations? I am interested in using my VBM output file as a covariate in my 3dMVM. Prior to running the 3dMVM with the VBM covariate I used 3dresample to change the voxel size of my VBM files to match the voxel size of my stats file (changed 1x1x1 to 2x2x2). After running this, I recieved the following error message:

Error in dim(vQV) ← c(dimx, dimy, dimz, length(unique(lop$dataStr[, lop$vQV[1]]))) :
dims [product 42024960] do not match the length of object [43281400]
Execution halted

I used 3dinfo to check the dimensions of my files and saw that the orientations were different (see below). Do these different orientations indicate that across the images the left side is not in fact the left, and the right side is not the right?

Is there another reason why I may be getting this error message?

Thank you very much,

original anatomical file used for VBM and fMRI analysis
Data Axes Orientation:
first (x) = Anterior-to-Posterior
second (y) = Superior-to-Inferior
third (z) = Right-to-Left [-orient ASR]

pre-processed stats file from AFNI:
Data Axes Orientation:
first (x) = Left-to-Right
second (y) = Posterior-to-Anterior
third (z) = Inferior-to-Superior [-orient LPI]

VBM output file
Data Axes Orientation:
first (x) = Right-to-Left
second (y) = Posterior-to-Anterior
third (z) = Inferior-to-Superior [-orient RPI]

Hi Tam,

When using 3dresample to match grids, it probably desirable to use the -master option, rather than specifying dimensions. Using -master will equate dimensions, numbers of voxels and orientations.

Does that seem like what you want?

  • rick

Yes, thank you very much!