I want to create a closed contour from hdr/img data

Support
1

Right now the contour runs into the boundary of the box, and it is then open. One thing that I could think of was to either surround the current volume with a layer of zero voxels (which would close the contour), or modify the volume itself by setting the voxels close to the boundary to zero.

Is this a good approach, hopefully supported by slicer. Or is there something better?

2

If you load the image as segmentation then this boundary is automatically added for you.

However, for this first you need to convert the legacy hdr/img format to nrrd or nifti. You can do that by loading the hdr/img file into Slicer as a Volume and then saving it in the new format.