How to get the opacity value at a point/cell (in world coordinate) on an object of vtkImageData

I made a line intersected with the vtkbox of vtkImageData volume and collected the intersection cell ids. I am wondering if vtk provide class or method to help me get the opacity value at each point/cell.

Thanks! It has made me confused for weeks.

I think you might be looking for the vtkProbeFilter class.
For retrieving an opacity value instead of just the value inside the vtkImageData, you might have to map the image data values through your transfer function yourself.

1 Like

Thanks! But I still can not find any examples related to both opacity value and vtkProbeFilter, if it is possible, can I ask you where can I find it on web?