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</o:shapelayout></xml><![endif]--></head><body lang=NL link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hi,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-GB>I’ve recently started a little project to create an image reader for a specific type of medical image data (Philips PAR/REC).<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>Hopefully I can do this neatly in VTK style, but I’m not pleased with the approach I’ve taken so far. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>I’d appreciate your take on this! Here’s my idea so far.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>vtkPARRECParser: to read the data properties. No troubles here<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>vtkPARRECReader: derives from vtkImageReader2<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>By default vtkImageReader is build to return a single slice or volume through the GetOutput function.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>My data also deals with time series. The vtkDICOMReader deals with series of slices, by stacking them into a volume.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>However, I’ll have to deal with series of volumes. So I thought: do not depair – there is the vtkTemporalDataSet.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>In the reader I have<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>ExecuteInformation – parses the parameters<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>ExecuteData (vtkDataObject* out) – get the info from the rec file.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Ah, so ‘out’ is a generic container. So I can cast types:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-family:"Courier New"'>if(singleTime)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-family:"Courier New"'>{<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> vtkImageData *data = <span style='color:blue'>this</span>->AllocateOutputData(out);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> // go get the data<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>}</span><span lang=EN-GB style='font-family:"Courier New"'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-family:"Courier New"'>else<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-family:"Courier New"'>{<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> vtkTemporalDataSet *data = vtkTemporalDataSet::New();<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> // go get the data<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> out->DeepCopy(data); <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>}</span><span lang=EN-GB style='font-family:"Courier New"'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Seems plausible, although the deepcopy is surely not preferable. The main issue I have with this<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>is the way the data set is returned to the application. GetOutput returns a vtkImageData, this being<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>a child of the vtkImageReader. My initial thought was to return as a vtkObject:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>vtkDataObject * GetOutput()<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>{<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> <span style='color:blue'>return</span> <span style='color:blue'>this</span>->GetOutputDataObject(0);<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>}<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>However, this leaves it up to the application to decide to which type it should downcast.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>This approach doesn’t ‘feel right’. What would you suggest to do to keep it in line with the VTK philisophy?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Thanks!</span><span lang=EN-GB><o:p></o:p></span></p></div></body></html>