Same reason as why the Editor module is missing

mac nightly 8-20
load volume
change zoom and pan in each of the three slice viewers
turn link on
hit adjust viewer fov button
the other two viewers are not reset.

I actually purposely implemented this feature this way in Slicer4 :)

Here is what I was struggling with. We can think of these view adjustment features as either "sending parameters to define a view" or "sending a command". In Slicer3, many of these features were implemented as "sending a command" when the really should be "sending parameters to define a view". I have been cleaning up these inconsistencies in Slicer4. I pondered whether to keep the reset the view to match Slicer3 or change its behavior to be like the rest of Slicer4 behavior.

Here is an example scenario. In one slice view, you increment the slice with the "f" key. If linking is on, Slicer should not send a message to "increment the slice" to the other viewers (who have the same orientation). Rather, after incrementing the slice of the current viewer, it should send the SliceToRAS matrix to the other viewers (that have the same orientation) so that they are looking at the scene coordinate frame from the same perspective.

I did the same thing with the reset the field of view. The slice viewer being interacted with determines the new field of view specification. That field of view specification is sent to all viewers with the same orientation. So if you reset the view on an axial, that new field of view specification is sent to all axial viewers.

Why is this important? Let's say we have two axial viewers that are showing different images. Let's say they are of the same patient but the acquisitions have two different spans (for the sake of argument, you can think of one being cropped). When you reset the field of view in one slice viewer, you probably want the images presented so that a centimeter in one image spans the same amount of anatomy as in the other image. In Slicer3, each of the viewers would have reset the view independently so that they all independently filled the field of view (causing anatomy to be scaled differently in each viewer). I think that is inconsistent with the Slicer concept of having a common coordinate frame for all images.

The question are::

1. Should reset the view act like a command performed independently in each viewer or should it act like setting parameters for a view that is propagated to the other viewers. I feel that we were doing it wrong in Slicer3.

2. Should reset the view restrict itself to just the viewers in the same orientation?

3. Should we have another way to allow the user to tell Slicer to rescale all the viewers to the native state (ignoring linking). This is the Slicer3 way to doing reset the view.

If I link some viewers, I would like modifications that I change to affect all linked viewer. Things that I do not change should not be affectd.

red axial, green sagittal, they are linked. reset fov affects both, with orientation not affected, since it was not changed.

This is the same issue as 0001378. It has been fixed while maintaining the code to perform the behavior of calculating the field of view for one viewer and prescribing that field of view for other viewers in the same orientation.

See 0001378 for more details.