Unfortunately, VTK doesn't support what most people think of as 2-dimensional transfer functions in Volume Mapping.<br><br>Look in the vtkVolumeProperty and you'll see an option for "IndependentComponents". Using that, you can switch it through a few modes:
<br>1) Map each scalar through it's own COlor & Opacity, and composite the results<br>2) Map the first scalar through color, and the second scalar through OPacity<br>3) Use the first 3 scalars as RGB directly, and map the 4th scalar through opacity.
<br><br>Using the Array-Calculator, and probably some custom code, you should be able to write code to generate a dataset with an RGBA (4-element) vector field and method #3 to get what you want.<br clear="all"><br>-- <br>
----------------------------------------<br>Randall Hand <br>Visualization Scientist<br>ERDC MSRC-ITL
<br><br><div><span class="gmail_quote">On 7/24/07, <b class="gmail_sendername">tony marrero</b> <<a href="mailto:tony.marrero@gmail.com">tony.marrero@gmail.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div>Hi guys,</div>
<div> </div>
<div>I am trying to implement a Multi Dimensional transfer function design; similar to the work done by Kindlmann and Kniss et Al.</div>
<div>I have not found anything useful in VTK to achieve this, there was also a similar question posted a few years ago but there was no response, i dont know if now more people are aware of how this can be achieved.</div>
<div> </div>
<div>In VTK, i have found colour and opacity mappings that take their domain from <strong>either</strong> scalar values or gradient lookup tables, but not both simultaneously.</div>
<div>I would like to have greater control over the rendering process , find a way to set colour and opacities to particular voxels of my choosing.</div>
<div> </div>
<div>Can someone kindly tell me how this can be achieved, or at least guide me in the correct direction.</div>
<div> </div>
<div>Thanks in advance,</div><span class="sg">
<div> </div>
<div>Tony Marrero</div>
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