Display problem with ColorTransferFunction

Hi, when I try the PaintWidge Example, I want to add more than one point of vtkColorTransferFunction which means label “1” will be gray and label “2” will be red for example.

labelMap.cfun.addRGBPoint(1, 1, 1, 1); // label "1" will be gray
labelMap.cfun.addRGBPoint(2, 1, 0, 0); // label "2" will be red

But when I set the label to “2” and paint some region, I found the drawn image borders are displayed in gray. Can anyone answer my confusion? Any suggestions will be helpful.
image

Here are some more obvious examples


Don’t you need to set a 255 to 0 value to your transfer function?

Hope it helps

Thanks for your reply. In Figure 1, I set “1” value to “1, 1, 1”(gray) and set “2” value to “1, 0, 0”(red). When I set the paint label to 1, paint operations can be displayed normally, but when I set the label to 2, the red region has a very thin gray borders. Is it a problem with my settings?

Maybe the values are float and go from 0 to 1

This doesn’t seem to work, the edges of the drawing area still have bugs displayed.

Try this method https://vtk.org/doc/nightly/html/classvtkProperty.html#a961853dcf5b86b4d6330076cc1f0af9e

Thank you

Which version of vtk.js are you using? If you are using a version >= v23.0.0, you will need to do the following:

actor.getProperty().setUseLookupTableScalarRange(true);

Hi, Forrest. I updated the dependencies(now 24.18.7) and added this statement, but the problem still exists. As show in the picture, I just added the following code according to PaintWidget Example

labelMap.cfun.addRGBPoint(1, 1, 0, 0); // label "1" will be red
labelMap.cfun.addRGBPoint(2, 0, 1, 0); // label "2" will be green
labelMap.cfun.addRGBPoint(3, 0, 0, 1); // label "3" will be blue
labelMap.actor.getProperty().setUseLookupTableScalarRange(true)

I think the problem is on the edge properties not on the colormapping table

I’ll throw out a few things to try:

  • actor.getProperty().setInterpolationType(InterpolationType.NEAREST);
  • setting the opacity function such that label 4 (or 3.001) is 0.
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It worked by setting the InterpolationType, thank you!