Experimental Physics and
Industrial Control System

Hi Josh,

The text you quote is from the description of an NTMatrix. That is not the normative type used by the areaDetector NDPluginPva plugin or the ImageJ viewer.  They use the NTNDArray normative type, which can have any number of dimensions. AD uses the normal convention for image data which has the first dimension being the number of columns and the second being the number of rows, e.g. a 1920x1200 monitor is [columns, rows].

Mark

Sent from my iPhone

On May 31, 2024, at 4:36 PM, Joshua Einstein-Curtis via Tech-talk <tech-talk at aps.anl.gov> wrote:



Hi all,

We're doing some work using PVXS and debugging using the ImageJ AD plugins, and I'm finding something that just doesn't make sense to me. Here's the run down:

For each pvxs::Value, we have two dimensions, as these are array values. Based on the specification in the documentation (https://docs.epics-controls.org/en/latest/pv-access/Normative-Types-Specification.html) I see:

" A dim] of 2 elements describes a matrix, where the first element of dim gives the number of rows, and the second element of dim gives the number columns."

When I set my array up and then send the image to the ImageJ NTNDA_Viewer plugin, I find that dims[0] is the x-axis, while dims[1] is the y-axis, which is the opposite of what I'd expect given the normative type specification.

Just curious if anyone else has run into this, or if I'm missing something obvious.

Josh EC

RadiaSoft