Hi Michael, There are some subtle but important differences between VisIt and ParaView when it comes to handling structured data:
1. VisIt's approach is to keep separate pieces - or domains or partitions, whatever you choose to call them - separate after loading a multi-piece dataset such as yours. They do this because it allows them several optimization specially on the IO side. On the other hand, ParaView treats structured datasets as one big thing, even though the pieces may be in separate files. When reading such datasets in parallel, ParaView will decide how to partition the dataset and have some MPI ranks read subsets of files that lie in the boundary, if necessary. So at the end, the partitioning of the two tools will end being very similar. ParaView may have a slight IO overhead if it needs to assign some files to multiple processes. The biggest difference is that the ParaView pipeline (the VTK pipeline actually) can make requests at a cell granularity whereas VisIt works at a piece granularity. Honestly, this is not a big difference for most scientific visualization application but it has a huge impact when analyzing medical datasets because of the algorithms involved. We are working towards integrating VisIt's design in addition to the traditional VTK way of dealing with structured data. To get a feel for it, you can replace your parallel rectilinear grid file with a multi-block file (vtm). You don't have to change the actual vtr files. I can describe how to do it if you don't already know. 2. In VisIt, the only type of rectilinear grid is vtkRectilinearGrid, which requires explicit storage of x, y and z coordinates. In VTK, hence ParaView, uniform rectilinear grids are best stored at vtkImageData. The advantage of this is minimal when it comes to memory usage but significant when it comes to algorithms. There are a large number of algorithms targeted to vtkImageData in VTK even though many of these are not exposed in ParaView by default. One of these algorithms is volume rendering. At this time, ParaView supports volume rendering of image data and unstructured grids only. In the next release (4.0 not 3.10), we will support volume rendering for more data types. I tried to explain this as much as I can without writing a whole book chapter. I hope it makes sense :-) By the way, if you are using .pvtr files, you don't need ghost zones (cells). ParaView will take care of loading ghost cells from neighbor pieces if necessary. As for the Tecplot files, are these binary files by any chance? Can you send me an example? Best, -berk On Thu, Feb 3, 2011 at 7:20 AM, Michael Scheerer <m_schee...@web.de> wrote: > Hi Berk, > > Thank you for the answer! > > An addition question: > > Paraview supports in the case of CGNS files volume rendering. > Volume rendering is in the list together with "Outline", "Surface" and so on. > This is not the case if someone tries to load VTK-files. > Why not? > > So I couldn't see, if the ghost zone overlap works in the sense, that all the > parts are really merged to one grid and not independent parts - even in the > case of volume rendering. > > Also PLT files crashes, although there are loadable with Tecplot and VisIt. > > Best, > Michael > ___________________________________________________________ > NEU: FreePhone - kostenlos mobil telefonieren und surfen! > Jetzt informieren: http://produkte.web.de/go/webdefreephone > _______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the ParaView Wiki at: http://paraview.org/Wiki/ParaView Follow this link to subscribe/unsubscribe: http://www.paraview.org/mailman/listinfo/paraview