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Kitware / VolView

Kitware VolView: an all-in-one radiological viewer!
https://volview.kitware.com
Apache License 2.0
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Recorded intensities extends lower than what the color/opacity transfer function editor displays - can't assign a color to lowest recorded value. #159

Open aylward opened 1 year ago

aylward commented 1 year ago

I can slide the opacity function well past the lower bounds of the displayed histogram, and the 3D image will continue to change.

Below - the opacity function looks the same in both images, but in the second image I kept sliding the opacity function to the right, and even though it looks like nothing was changing in the mapping from intensity to opacity, clearly it was changing...

image image
aylward commented 1 year ago

If a color with non-zero opacity is assigned to intensity 0, then a solid block should be shown.

Also, moving the opacity to the left keeps changing the appearance, even if opacity is set to 1 everywhere.

floryst commented 1 year ago

Needs re-evaluation.

aylward commented 11 months ago

Even with the new Shift and Width sliders, this problem persists.

If I scroll fully to the left, the opacity function ends / disappears / goes-to-zero, but all of the data is still shown as if the opacity function has a value of 1 everywhere.

To replicate / illustrate: 1) Here it the initial rendering image

2) Here is what I see after moving the opacity function fully to the left (opacity should be 0 for every recorded value, but every recorded value has an opacity of 1): image

floryst commented 11 months ago

I suspect this is due somewhere setting the max value of the dataset to be fully opaque instead of basing it on the effective opacity function.

What is the desired behavior? Should we match to what the opacity function looks like (bug is in setting the opacity function) or render the opacity function to be fully opaque at the end (bug is in the opacity editor)?

aylward commented 11 months ago

I think it should match what is shown in the function...but the last value in the function should extend to all larger values and not necessarily go 0 or 1.

On Fri, Sep 15, 2023, 1:28 PM Forrest Li @.***> wrote:

I suspect this is due somewhere setting the max value of the dataset to be fully opaque instead of basing it on the effective opacity function.

What is the desired behavior? Should we match to what the opacity function looks like (bug is in setting the opacity function) or render the opacity function to be fully opaque at the end (bug is in the opacity editor)?

— Reply to this email directly, view it on GitHub https://github.com/Kitware/VolView/issues/159#issuecomment-1721615862, or unsubscribe https://github.com/notifications/unsubscribe-auth/AACEJL7SS7QPZF2IWEROGKLX2SF23ANCNFSM6AAAAAARHKU5RI . You are receiving this because you were assigned.Message ID: @.***>