<DIV>Hi, </DIV>
<DIV>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman">I would need some advice in using VtkStreamTracer, at the INPUT part. I am doing the next thing: I am setting as input of the VtkStreamTracer a vtkImageData which has set as vectors a vtkDoubleArray and I am doing that for each vector field in a for cycle.(the result is the same if I use SetInput or AddInput). <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman">My concern is that the integrator has access at only one vector field at a time, so even if I use RK45 the resulted stream lines are not smooth (is almost like<SPAN style="mso-spacerun: yes"> </SPAN>Eulers integration method, which considers the slope only at the beginning of the interval).<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman">My question is HOW TO BUILD the INPUT such that the integrator has access to all the vector fields.</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT face="Times New Roman" size=3>I'll be thankfull for any information .</FONT></SPAN><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT face="Times New Roman" size=3>Thanks a lot ! </FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT face="Times New Roman" size=3>Dan</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman">I attached some code below:</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><o:p><FONT face="Times New Roman" size=3> </FONT></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>self.vector2D= vtkImageData()<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>motion2D = vtkImageData()<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-tab-count: 1"> </SPAN><SPAN style="mso-spacerun: yes"> </SPAN>self.streamtracer = vtkStreamTracer()<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>.........................<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>vectors=vtkDoubleArray()<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>vectors.SetNumberOfComponents(3)<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>vectors.SetNumberOfTuples(self.dims[0]*self.dims[1]*self.dims[2])<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN># Vectors to use with streamtracer<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>for k in range(self.nbimages):<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN># Append reader<SPAN style="mso-spacerun: yes"> </SPAN>for every vector field image<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>self.reader.append(vtkImageReader())<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-tab-count: 1"> </SPAN><SPAN style="mso-spacerun: yes"> </SPAN>
.. <SPAN style="mso-tab-count: 1"> </SPAN><o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>self.reader[k].SetFileName(fname)<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN># Read motion data stored in a 2 components ACR image file<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>............................................<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN># Store 2D Motion in ImageData and update vector2D<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>motion2D =self.reader[k].GetOutput()<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>......................................<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>for y in range(self.dims[1]):<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>jOffset = y * self.dims[0]<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>for x in range(self.dims[0]):<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>v[0]=motion2D.GetScalarComponentAsDouble(x,y,0,0)<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN><SPAN style="mso-spacerun: yes"> </SPAN>v[1]=motion2D.GetScalarComponentAsDouble(x,y,0,1)<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>offset = x + jOffset<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>vectors.InsertTuple3(offset,v[0],v[1],0)<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>self.vector2D.GetPointData().SetVectors(vectors)<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN><SPAN style="mso-spacerun: yes"> </SPAN># Perform StreamTracer process (on vector field)<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN># Set motion field<SPAN style="mso-spacerun: yes"> </SPAN>& seeds<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>self.streamtracer.AddInput(self.vector2D)<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>#self.streamtracer.SetInput(self.vectorField)<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>self.streamtracer.SetSource(self.seedgrid[k])<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT size=3><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>self.streamtracer.Update()<o:p></o:p></FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><o:p><FONT face="Times New Roman" size=3> </FONT></o:p></SPAN></P></DIV><BR><BR><DIV>
<P align=center><FONT face="Comic Sans MS"><FONT color=#0080ff>Onica Dan</FONT> <IMG src="http://us.i1.yimg.com/us.yimg.com/i/mesg/tsmileys2/23.gif"></FONT></P>
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