[vtkusers] vtkVolumeProperty IndependentComponents On and Off

[Kenji Tsumura]

Hello,

I have 3D cardiac MRI data (magnitude data and velocity data), and would like to display the volume rendering of the two data.
I create vtkVolume with two components  (first one is velocity data and second one is magnitude data) and use vtkSmartVolumeMapper.
When I set IndependentComponentsOn to the volume property, I can see what I want (refer to the first figure).
But this setting disables GPU rendering and it is slow.
My understanding is that I have to use IndependentComponentsOff to make the mapper use GPU rendering.
When I set IndependentComponentsOff, only one color transfer function, and only one scalar opacity function to the volume property,
the magnitude data (the second component) is also color-coded (refer to the second figure).
I thought this contradicts the method comments of IndependentComponentsOn/ IndependentComponentsOff.

"For 2 component data, the first is passed through the first color transfer function and the second component is passed through the first opacity transfer function."

Am I missing something?
Can I make the volume rendering look the same as using two components?

Thank you,

BTY, I use v6.3.0, OpenGL2.

--
Kenji Tsumura

"The information contained in this communication may be confidential, is intended only for the use of the recipient(s) named above, and may be legally privileged. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication, or any of its contents, is strictly prohibited. If you have received this communication in error, please return it to the sender immediately and delete the original message and any copy of it from your computer system. If you have any questions concerning this message, please contact the sender.
Disclaimer: The information contained in this communication may be confidential, is intended only for the use of the recipient(s) named above, and may be legally privileged. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication, or any of its contents, is strictly prohibited. If you have received this communication in error, please return it to the sender immediately and delete the original message and any copy of it from your computer system. If you have any questions concerning this message, please contact the sender.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20151207/e5182d28/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: IndependentComponentsOff.jpg
Type: image/jpeg
Size: 20043 bytes
Desc: IndependentComponentsOff.jpg
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20151207/e5182d28/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: IndependentComponentsOn.jpg
Type: image/jpeg
Size: 33293 bytes
Desc: IndependentComponentsOn.jpg
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20151207/e5182d28/attachment-0001.jpg>