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Hi Mark,<br><br>
Yes - you do need a color function and you should probably set it to
solid white to achieve the effect you are looking for. You probably have
a gray ramp color function. For both maximize methods the opacity
transfer function plays a role - in the maximize scalar value method the
maximum scalar value is found, then this scalar value is passed through
the opacity and color function to determine the final pixel value. In the
maximize opacity method, each scalar value is passed through the opacity
function and the one with the maximum opacity is selected. This would
allow you to, for example, actually do minimum opacity (with an inverse
opacity ramp) <br><br>
You can render the volume into an offscreen image, capture that, display
that as an image and use W/L operations on it. This is the same as
adjusting the opacity transfer function when in maximize scalar value
mode, but not when in maximize opacity mode.<br><br>
Lisa<br><br>
<br><br>
At 11:55 AM 9/2/2005, Mark Wyszomierski wrote:<br>
<blockquote type=cite class=cite cite="">Hi Lisa,<br>
<br>
First I had my MIP function using
<font size=2>SetMaximizeMethodToScalarValue(), and it looks like setting
the opacity transfer function had no effect. If I switch to
SetMaximizeMethodToOpacity(), then the transfer function does have an
effect, though it is a strange effect. The areas of my organ dataset that
have the greatest intensity will appear as bright white both in the 2D
slices, and in the MIP rendering if maximize scalars is on (areas like
veins/artieries etc). Now that I set maximize to use opacity, and
adjusted the ramp, yes I can have only those really bright areas stand
out, but since their opacity is high I guess they are really dark grey
now! It almost looks like an inverted MIP. Should I specify a color
mapping now too? My input is one component unisigned short. <br>
</font> <br>
<font size=2>The window and leveling for the image viewer classes is very
interactive with good response times. If I were to try the same thing
binding the opacity ramp to be interactive for this volume, I can get a
refresh maybe once every 1 - 2 seconds per change. That's why I am still
wondering about hooking into the output of the rendered volume somehow,
so window / level would only be done on the output image instead of every
voxel in the volume, then resampling etc, does this sound
feasible/possible? <br>
</font> <br>
I posted the relevant lines for my MIP below in case I'm doing something
wrong:<br>
<br>
OpacityTransferFunction->AddPoint(0, 0);<br>
OpacityTransferFunction->AddPoint(0, 300.0);<br><br>
Volume->SetProperty(VolumeProperty);<br>
CompositeFunctionMIP->SetMaximizeMethodToOpacity();<br>
VolumeMapper->SetVolumeRayCastFunction(CompositeFunctionMIP);<br>
VolumeMapper->SetInput((*this->pImageData)); <br>
Volume->SetMapper(VolumeMapper);<br><br>
Thank you!<br><br>
On 9/2/05, <b>Lisa Avila</b>
<<a href="mailto:lisa.avila@kitware.com">lisa.avila@kitware.com</a>
> wrote: <br>
<dl>
<dd>Hello,<br><br>
<dd>You would apply the window / leve directly to the opacity transfer
function<br>
<dd>- just adjust the start / end points of the ramp. If it is too dark,
lower <br>
<dd>the point at which the opacity becomes 1.<br><br>
<dd>Lisa<br><br>
<dd>At 09:03 AM 9/2/2005, powerhouseofexcellence wrote:<br>
<dd>>Hi all,<br>
<dd>><br>
<dd>>I have the VTK users guide book (version 4.4) and was reading to
see how<br>
<dd>>to edit the diffuse/ambient etc to make my volumes look brighter
(problem<br>
<dd>>from an earlier post). But I'm doing a MIP, and the book says
that these<br>
<dd>>parameters and the ShadingOn() are ignored by MIP rendering. So
my MIP <br>
<dd>>still looks dark, any way to increase their brightness? I am
using the<br>
<dd>>scalar value as the maximize function.<br>
<dd>><br>
<dd>>I was hoping that since the volume data is being passed to the
render<br>
<dd>>window somewhere, maybe there would be a chance to set the output
of the <br>
<dd>>volume renderer into a window level filter which is then passed
along to<br>
<dd>>the render window. So only the final output is window/leveled and
this<br>
<dd>>could be a quick operation. Is this possible?<br>
<dd>><br>
<dd>>Thanks<br>
<dd>>_______________________________________________<br>
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