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<DIV><FONT size=2>Hi,</FONT></DIV>
<DIV><FONT size=2>I was vol. rendering a vtkStructuredPoints using the Ray
Casting method and I wanted to move the actor (represented as vtkVolume) using
the (SetUserMatrix) method and then render again. However, I get the following
error when I do that:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>ERROR: In D:\vtk31\graphics\vtkViewRays.cxx, line
126</FONT></DIV>
<DIV><FONT size=2>vtkViewRays (0x0745E0c0): View Rays has a 0 area, must
SetSize() to area > 0</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>This only happens when I render, then change the actor
transformation using the SetUserMatrix, and then try to render again. However,
if I set the user matrix before I render, no error occurs. My problem is that
I'm performing registration and I need to display the vtkVolume object with
multiple consecutive transformations.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>Any help will be greately appreciated.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>Thanks</FONT></DIV>
<DIV><FONT size=2>Asad</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>==============================================</FONT></DIV>
<DIV><FONT size=2>The code that generates the error:</FONT></DIV>
<DIV><FONT size=2>renderer1->AddVolume(MyVolume);</FONT></DIV>
<DIV><FONT size=2>// render. </FONT></DIV>
<DIV><FONT size=2>// do some calculations and wait for user input.</FONT></DIV>
<DIV><FONT size=2>MyVolume->SetUserMatrix(MyMatrix)</FONT></DIV>
<DIV><FONT size=2>// render again. (here is were I get the error).</FONT></DIV>
<DIV><FONT size=2>================================================</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>No error occurs when I don't render the first time (do the
calculation and just render the volume after the transformation).</FONT></DIV>
<DIV><FONT size=2><BR> </DIV></FONT></BODY></HTML>