# Unable to exceed incumbent 'maximum' in Volume Rendering module by text entry
**URL:** https://discourse.slicer.org/t/unable-to-exceed-incumbent-maximum-in-volume-rendering-module-by-text-entry/21535
**Category:** Support
**Created:** [January 20, 2022, 12:46am UTC](https://discourse.slicer.org/t/unable-to-exceed-incumbent-maximum-in-volume-rendering-module-by-text-entry/21535 "2022-01-20T00:46:26Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@DIV](https://discourse.slicer.org/u/DIV)
#### Post date: [January 20, 2022, 12:46am UTC](https://discourse.slicer.org/t/unable-to-exceed-incumbent-maximum-in-volume-rendering-module-by-text-entry/21535/1 "2022-01-20T00:46:26Z")
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…
> [@Trouble with thresholding](https://discourse.slicer.org/t/trouble-with-thresholding/21332/5):
>
> 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.
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### Author:  [@DIV](https://discourse.slicer.org/u/DIV)
#### Post date: [January 20, 2022, 3:34am UTC](https://discourse.slicer.org/t/unable-to-exceed-incumbent-maximum-in-volume-rendering-module-by-text-entry/21535/2 "2022-01-20T03:34:54Z")
The text entry field for `X` in the “Gradient Opacity” control doesn’t seem to allow text entry at all.
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### Author:  [@pieper](https://discourse.slicer.org/u/pieper)
#### Post date: [January 21, 2022, 6:39pm UTC](https://discourse.slicer.org/t/unable-to-exceed-incumbent-maximum-in-volume-rendering-module-by-text-entry/21535/3 "2022-01-21T18:39:10Z")
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.