<div style="white-space:pre-wrap">Hi David,<br><br>I wish I could do that. The CFD simulator spits out result files that are easily tens of GB of data, and clearly I can't load all that stuff inside my tool at once. The simulator itself produces smaller "support" output files that only contain "pointers" to where the results are stored in the big output files (pointers in the file.seek sense).<br><br>Andrea.<br></div><br><div class="gmail_quote"><div dir="ltr">On Mon, 28 Nov 2016 at 17:39, David Lonie <<a href="mailto:david.lonie@kitware.com">david.lonie@kitware.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg">+1 to what other Dave said. I'd also point out that you can simply add all of the potential scalars you'd like to use to the point/cell/field data as named arrays, and then use the vtkMapper::SelectColorArray method to select the property to use for visualization.<div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">This way, the threshold/DSSF pipeline would only execute once and will produce a dataset with all of the property arrays filtered to just the active set. Changing the visible scalars at the mapper level will not cause the pipeline to re-execute.</div></div><div class="gmail_extra gmail_msg"><br class="gmail_msg"><div class="gmail_quote gmail_msg"></div></div><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg">On Mon, Nov 28, 2016 at 7:35 AM, Andrea Gavana <span dir="ltr" class="gmail_msg"><<a href="mailto:andrea.gavana@gmail.com" class="gmail_msg" target="_blank">andrea.gavana@gmail.com</a>></span> wrote:<br class="gmail_msg"></div></div><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">Dear All,</font><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"><br class="gmail_msg"></font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"> I am working with some stuff coming out of CFD simulations, and in the current work the simulator produces a 3D grid (unstructured grid made of hexahedrons). The full grid is about 4 million cells, but due to other settings in the simulator the number of "active" cells in the simulation ends up being "only" 270,000. In order to visualize all this, I create a vtkUnstructuredGrid to hold the full grid, use a vtkThreshold to remove the "inactive" cells and then use a vtkDataSetMapper to visualize the resulting active grid:</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"><br class="gmail_msg"></font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">vtkUnstructuredGrid --> vtkThreshold --> vtkDataSetMapper --> vtkActor<br class="gmail_msg"></font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"><br class="gmail_msg"></font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">However, the rendering speed for the 270,000 cells grid is quite low - it takes about one second to display a new property by using SetScalars on the output of vtkThreshold. So I thought of using a vtkDataSetSurfaceFilter on the output of vtkThreshold to try and speed up the rendering. So, the current visualization strategy I have implemented is the following:</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"><br class="gmail_msg"></font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">vtkUnstructuredGrid --> vtkThreshold --> vtkDataSetSurfaceFilter --> vtkPolyDataMapper --> vtkActor</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"><br class="gmail_msg"></font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">This is still as slow as my first approach, and I also have a couple of questions - which stems from my ignorance in VTK things:</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"><br class="gmail_msg"></font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">1. When I load (from the simulator outputs) a new property (cell-based) and I assign its values to the original vtkUnstructuredGrid (by using SetScalars on it), do all the filters (vtkThreshold and vtkDataSetSurfaceFilter) need to be re-run? If yes, why? I am not changing the active/inactive cells nor the geometry of the grid, only assigning different scalars. And, if yes, is there any way to tell the pipeline: "look, I've only changed the scalars, there's no need to re-run all the thresholds and surface filters *again*"?</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"><br class="gmail_msg"></font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">2. Is there any other pipeline style or visualization technique in VTK or any settings whatsoever that could bring down the rendering time (memory is not that much of a concern)? Basically, what I have a the moment - in terms of timing - is as follows:</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"><br class="gmail_msg"></font></div><div class="gmail_msg"><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">Reading data from simulator: 0.042 seconds</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">Create VTK array with data : 0.002 seconds</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">Call to SetScalars : 0.000 seconds</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">Create Lookup Table : 0.001 seconds</font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">Render on screen : about 1 second</font></div><div class="gmail_msg"><br class="gmail_msg"></div></div><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">Thank you in advance for any suggestion, my apologies for the long message.</font></div><span class="m_8656592201015417679HOEnZb gmail_msg"><font color="#888888" class="gmail_msg"><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg"><br class="gmail_msg"></font></div><div class="gmail_msg"><font face="monospace, monospace" class="gmail_msg">Andrea.</font></div></font></span></div>
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