Unable to exceed incumbent 'maximum' in Volume Rendering module by text entry

[DIV]

In the Volume Rendering module under Advanced there are settings for Scalar Opacity Mapping and Scalar Color Mapping.

If the largest preset X value in the series of points in either set is smaller than the maximum image intensity, and if the user would like to therefore increase the value of X by typing it in, the current GUI prevents it.
I find that inconvenient & unintuitive, and am not sure what benefit (if any) accrues from this constraint on the entry field.

There are some workarounds…

@DIV

There is a kind of limitation in 3D Slicer that will prevent a user from entering an intensity value in the opacity or colour mapping that’s above some nominal ‘maximum’ by directly typing it in. (Some people might call this a bug.) The workarounds are to either drag the rightmost grey circular knob to the far right, or to manually edit the VP file. It’s not very convenient.

…but if there’s no big advantage to retaining the constraint, it would be good to remove it.

Alternatively, perhaps a softer constraint could be imposed: e.g. prevent the user from entering a value higher than the actual maximum image intensity (or perhaps double it, say), rather than just whatever the old/existing volume rendering setting happened to be.

—DIV

P.S. In the first workaround, after dragging the respective grey circular knob to the right, if the mouse reaches the edge of the the user’s screen, then the rectangular grey knob of the scrollbar may also need to be dragged to the right in order to access even higher values. These are annotated in the screenshot above.

[DIV]

The text entry field for X in the “Gradient Opacity” control doesn’t seem to allow text entry at all.

[pieper (Steve Pieper (Isomics, Inc.))]

The Volume Rendering widgets have a lot of usability challenges and could really stand a refresh. There are many new features we could expose too. It would be great if someone wants to take this work.