I apologize for hastily committing this. I have reverted it back.<br><br><div class="gmail_quote">On Wed, Jul 14, 2010 at 10:23 AM, Karthik Krishnan <span dir="ltr"><<a href="mailto:karthik.krishnan@kitware.com">karthik.krishnan@kitware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">This behaviour has always existed in vtkImageActor - due to the way VTK deals with point data and cell data and the fact that
the tips of the render window delineate the available screen pixels for
display. What this means is that the tips of the clipped rectangle you
are seeing (and the centers of any other rectangle) correspond to the
positions of the centers of vtkImageData voxels. Because the display
extent, in word coordinates runs from the Word position of the left
edge voxel center to the world position of the right edge voxel center,
you end up with clipping.<br>
<br>
This has been the topic of discussion on the list before.<br>
<br>
I don't believe that the fix you proposed can resolve that. Does it ?
It would simply cause one to update the whole input needlessly leading
to slowness when one renders a vtkImageActor for the very first time,
without setting the DisplayExtent.<br>
<br>
Thanks<br>
--<br><font color="#888888">
karthik</font><div><div></div><div class="h5"><br><br><div class="gmail_quote">On Wed, Jul 14, 2010 at 7:43 PM, Dave Partyka <span dir="ltr"><<a href="mailto:dave.partyka@kitware.com" target="_blank">dave.partyka@kitware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
Hi David Gobbi,<div><br></div><div>It appears from git blame that you are the author, or at least, the last person to modify this code. What are your thoughts? Is this a bug or intended as Karthik described?</div><div><br>
</div><div>The blobs of code are:</div><div><br></div><div><div> // if the display extent has not been set, then compute one</div><div><div> int *wExtent = input->GetWholeExtent();</div><div> if (this->DisplayExtent[0] == -1)</div>
<div> {</div><div> this->ComputedDisplayExtent[0] = wExtent[0];</div><div> this->ComputedDisplayExtent[1] = wExtent[1];</div><div> this->ComputedDisplayExtent[2] = wExtent[2];</div><div> this->ComputedDisplayExtent[3] = wExtent[3];</div>
<div> this->ComputedDisplayExtent[4] = wExtent[4];</div><div> this->ComputedDisplayExtent[5] = wExtent[4];</div><div> }</div></div></div><div><br></div><div>and</div><div><br></div><div><div> // if the display extent has not been set, then compute one</div>
<div> int *wExtent = this->Input->GetWholeExtent();</div><div><div> if (this->DisplayExtent[0] == -1)</div><div> {</div><div> this->ComputedDisplayExtent[0] = wExtent[0];</div><div> this->ComputedDisplayExtent[1] = wExtent[1];</div>
<div> this->ComputedDisplayExtent[2] = wExtent[2];</div><div> this->ComputedDisplayExtent[3] = wExtent[3];</div><div> this->ComputedDisplayExtent[4] = wExtent[4];</div><div> this->ComputedDisplayExtent[5] = wExtent[4];</div>
<div> }</div><div><br></div><br></div><div><div></div><div><div class="gmail_quote">On Wed, Jul 14, 2010 at 9:54 AM, Karthik Krishnan <span dir="ltr"><<a href="mailto:karthik.krishnan@kitware.com" target="_blank">karthik.krishnan@kitware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">Dave:<br><br>I would recommend holding off that commit. I'm not convinced that its a bug. Specifically, the fragment of code reads :<br>
<br><br>int vtkImageActor::RenderOpaqueGeometry(vtkViewport* viewport)<br>{<br>....<br>
<br> int *wExtent = input->GetWholeExtent();<br> if (this->DisplayExtent[0] == -1)<br> {<br> this->ComputedDisplayExtent[0] = wExtent[0];<br> this->ComputedDisplayExtent[1] = wExtent[1];<br> this->ComputedDisplayExtent[2] = wExtent[2];<br>
this->ComputedDisplayExtent[3] = wExtent[3];<br> this->ComputedDisplayExtent[4] = wExtent[4];<div><br> this->ComputedDisplayExtent[5] = wExtent[4];<br> }<br></div> input->SetUpdateExtent(this->ComputedDisplayExtent);<br>
...<br>}<br><br>An ImageActor should have flattened extents along some dimension. It does not make sense for the ImageActor to update the WHOLE input. It appears that with the fix, "this->ComputedDisplayExtent[5] = wExtent[4];", it will lead to updating the entire image. <br>
<br>I think the author of the class simply intended to set the display extent to the first axial slice if they haven't been set.<br><br>Pavel: I'm also interested in knowing how you uncovered/ concluded that this is a bug. We use vtkImageActor quite heavily and haven't had any issues; Maybe we haven't covered this "if" block, but still, its good to know..<br>
<br>Thanks<br>--<br><font color="#888888">karthik</font><div><div></div><div><br><br><div class="gmail_quote">On Wed, Jul 14, 2010 at 7:09 PM, Dave Partyka <span dir="ltr"><<a href="mailto:dave.partyka@kitware.com" target="_blank">dave.partyka@kitware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
Hi Pavel, I am curious how you discovered this bug. Were you just browsing through the file or do you have code that is affected by this? If so would you mind sharing it? I would like to make a test out of it if possible.<div>
<div></div><div><br>
<br><div class="gmail_quote">On Wed, Jul 14, 2010 at 9:26 AM, Dave Partyka <span dir="ltr"><<a href="mailto:dave.partyka@kitware.com" target="_blank">dave.partyka@kitware.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
Those lines are definitely covered. Though it appears the only are used when the extents haven't been set yet.<div><br></div><div><a href="http://www.cdash.org/CDash/viewCoverageFile.php?buildid=663956&fileid=10980615" target="_blank">http://www.cdash.org/CDash/viewCoverageFile.php?buildid=663956&fileid=10980615</a><div>
<div></div><div><br>
<br><div class="gmail_quote">On Wed, Jul 14, 2010 at 9:18 AM, David Cole <span dir="ltr"><<a href="mailto:david.cole@kitware.com" target="_blank">david.cole@kitware.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
This sort of error looks like it should produce some sort of seriously incorrect results.<div><br></div><div>Do we not have a test that covers this code? Is the coverage for the lines in question "0" or do we just not have a *good* test that runs through that code...?</div>
<div><br></div><div>I would think vtkImageActor is a heavily used class.</div><div><br></div><div><br>?</div><div><div></div><div><div><br></div><div><br><div class="gmail_quote">On Wed, Jul 14, 2010 at 8:51 AM, Dave Partyka <span dir="ltr"><<a href="mailto:dave.partyka@kitware.com" target="_blank">dave.partyka@kitware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">Thanks for the fix! I have just committed it.<br><br><div class="gmail_quote"><div><div></div>
<div>On Wed, Jul 14, 2010 at 4:19 AM, Pokutnev, Pavel (GE EntSol, SensInsp) <span dir="ltr"><<a href="mailto:Pavel.Pokutnev@ge.com" target="_blank">Pavel.Pokutnev@ge.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex"><div><div></div><div>
<div>
<div><font face="Arial" size="2"><span>Hello
vtk-devs,</span></font></div>
<div><font face="Arial" size="2"><span></span></font> </div>
<div><font face="Arial" size="2"><span>it looks like there
is a copy & paste bug in vtkImageActor line 250 and
293:</span></font></div>
<div><font face="Arial" size="2"><span></span></font> </div>
<div><font face="Arial" size="2"><span>The
line:</span></font></div>
<div><font face="Arial" size="2"><span>
this->ComputedDisplayExtent[5] = wExtent[4];</span></font></div>
<div><font face="Arial" size="2"><span>should
be:</span></font></div>
<div><font face="Arial" size="2"><span>
this->ComputedDisplayExtent[5] = wExtent[5];</span></font></div>
<div><font face="Arial" size="2"><span></span></font> </div>
<div><font face="Arial" size="2"><span>Best
regards!</span></font></div>
<div><font face="Arial" size="2"><span></span></font> </div>
<div><font face="Arial" size="2"></font> </div><font face="Arial" size="2">
<div align="left"><br></div></font>
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