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<DIV><FONT face=Arial size=2>Hi Lisa,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thank you for your prompt reply.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>When I combined the source code and screenshots for
your example I "noticed" a little bug. The problem is that we used vtkShiftScale
for MIP raycaster which worked fine, fixed point MIP did not use vtkShiftScale,
but there was some classification problem because of that. So forget about MIP
problems:)</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I must say that vtkFixedPointVolumeRayCastMapper is
really good and it solves a lot of problems for us.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>>switch the vtkFixedPointVolumeRayCastMapper over to using this</DIV>
<DIV>Is there any catch or I just have to copy the code from
RayCastMapper?</DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Warm Regards,</FONT></DIV>
<DIV><FONT face=Arial size=2>Mario</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=lisa.avila@kitware.com href="mailto:lisa.avila@kitware.com">Lisa
Avila</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=mario.medved@xlab.si
href="mailto:mario.medved@xlab.si">Mario Medved</A> ; <A
title=vtkusers@public.kitware.com
href="mailto:vtkusers@public.kitware.com">vtkusers@public.kitware.com</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, September 29, 2005 6:04
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [vtkusers]
vtkFixedPointVolumeRayCastMapper features</DIV>
<DIV><FONT face=Arial size=2></FONT><FONT face=Arial
size=2></FONT><BR></DIV>Hi Mario,<BR><BR>For your first problem: I am unaware
of this. Can you cause it on one of the VTK data sets? If so, can you send me
the code that causes it so I can try it?<BR><BR>On the second issue - yes, the
vtkFixedPointVolumeRayCastMapper does use its own code for generating
gradients since the gradient estimator is not able to process multicomponent
data. Originally, the vtkFixedPointVolumeRayCastMapper relied on a specific
gradient encoding since it used to interpolate normals (Phong-style shading)
but that turned out to be too unstable so it interpolates shaded value (just
like the standard ray cast mapper). So - it should be possible to expand the
gradient estimator to handle multi component data, switch the
vtkFixedPointVolumeRayCastMapper over to using this, and then everything will
run faster on a multiprocessor system (although keep in mind that the code in
the fixed point mapper tries harder to get a gradient in homogeneous regions -
looking out at larger distances until it finds one with a sufficient magnitude
- now that we are not interpolating gradients perhaps this is not
necessary....). <BR><BR>Lisa<BR><BR><BR>At 08:53 AM 9/28/2005, Mario Medved
wrote:<BR>
<BLOCKQUOTE class=cite cite="" type="cite"><FONT
face="Times New Roman, Times">Hi,<BR><BR>I was experimenting with
vtkFixedPointVolumeRayCastMapper which is great, <BR>but I noticed 2
problems/features:<BR><BR>1. MIP blend mode causes black spots over some
images. I think this is due <BR>space leaping, since vtkVolumeRayCastMapper
does not have these problems.<BR><BR>2. When the shading is turned on, the
gradient estimator works slower then <BR>in vtkVolumeRayCastMapper. On
larger volumes this can be very lengthy <BR>operation. I checked the source
code and there is just block of code for <BR>calculating gradient values
directly without any multiprocessor support. <BR>vtkVolumeRayCastMapper uses
gradient estimator object which does all <BR>calculations with miltiproc
support, but I am not sure why this code is not <BR>used in
vtkFixedPointVolumeRayCastMapper.<BR><BR>If anyone solved these problems,
please let mo know, so I do not rediscover <BR>hot
water.<BR><BR>Thanks,<BR>Mario </FONT><FONT face=arial
size=2><BR></FONT>_______________________________________________<BR>This is
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