[vtkusers] Basic question, vtkStructuredPoints
Oeyvind Knudsen
knudsen at operamail.com
Wed Feb 11 17:52:40 EST 2004
Hi!
Thanks for the tip. Actually, I tried something similar:
spData = vtkStructuredPoints()
spData.SetDimensions(81, 81, 1)
spData.SetOrigin(0.0, 0.0, 0.0)
spData.SetSpacing(1.0, 1.0, 1.0)
pData = spData.GetPointData()
dArray = vtkDoubleArray()
dArray.SetName("double Array")
dArray.SetVoidArray("self.scalars", len(self.scalars), 1)
pData.SetScalars(dArray)
(self.scalars is the array of data given as argument)
Would this be similar to your suggestion? The problem here is that the resulting object spData, does not look like the vtkStructuredPoints object obtained from the file at all.
In fact the object given from the file reader looks quite empty, with no point data, no array, no nothing, not even the dimensions set correctly. Despite that, the surface is rendered. Here is the result of a simple print of the constructed object from python:
vtkStructuredPoints (0x842fb90)
Debug: Off
Modified Time: 498
Reference Count: 2
Registered Events: (none)
Source: (none)
Release Data: Off
Data Released: False
Global Release Data: Off
MaximumNumberOfPieces: -1
PipelineMTime: 0
UpdateTime: 0
UpdateExtent: Not Initialized
Update Number Of Pieces: 1
Update Piece: 0
Update Ghost Level: 0
RequestExactExtent: Off
UpdateExtent: 0, 0, 0, 0, 0, 0
WholeExtent: 0, -1, 0, -1, 0, -1
Field Data:
Debug: Off
Modified Time: 448
Reference Count: 1
Registered Events: (none)
Number Of Arrays: 0
Number Of Components: 0
Number Of Tuples: 0
Locality: 0
NumberOfConsumers: 0
ExtentTranslator: (0x83d3d58)
MaximumNumberOfPieces: -1
Number Of Points: 6561
Number Of Cells: 6400
Cell Data:
Debug: Off
Modified Time: 452
Reference Count: 1
Registered Events: (none)
Number Of Arrays: 0
Number Of Components: 0
Number Of Tuples: 0
Copy Flags: ( 1 1 1 1 1 )
Scalars: (none)
Vectors: (none)
Normals: (none)
TCoords: (none)
Tensors: (none)
Point Data:
Debug: Off
Modified Time: 498
Reference Count: 3
Registered Events: (none)
Number Of Arrays: 1
Array 0 name = double Array
Number Of Components: 1
Number Of Tuples: 6561
Copy Flags: ( 1 1 1 1 1 )
Scalars: Debug: Off
Modified Time: 495
Reference Count: 3
Registered Events: (none)
Name: double Array
Number Of Components: 1
Number Of Tuples: 6561
Size: 6561
MaxId: 6560
LookupTable: (none)
Array: 0x44518584
Vectors: (none)
Normals: (none)
TCoords: (none)
Tensors: (none)
Bounds:
Xmin,Xmax: (0, 80)
Ymin,Ymax: (0, 80)
Zmin,Zmax: (0, 0)
Compute Time: 0
Release Data: Off
ScalarType: 10
NumberOfScalarComponents: 1
Spacing: (1, 1, 1)
Origin: (0, 0, 0)
Dimensions: (81, 81, 1)
Increments: (1, 81, 6561)
Extent: (0, 80, 0, 80, 0, 0)
WholeExtent: (0, -1, 0, -1, 0, -1)
And here is a print of reader.GetOutput():
vtkStructuredPoints (0x843e1b0)
Debug: Off
Modified Time: 553
Reference Count: 3
Registered Events: (none)
Source: 0x84971f8
Release Data: Off
Data Released: True
Global Release Data: Off
MaximumNumberOfPieces: -1
PipelineMTime: 0
UpdateTime: 0
UpdateExtent: Not Initialized
Update Number Of Pieces: 1
Update Piece: 0
Update Ghost Level: 0
RequestExactExtent: Off
UpdateExtent: 0, 0, 0, 0, 0, 0
WholeExtent: 0, -1, 0, -1, 0, -1
Field Data:
Debug: Off
Modified Time: 550
Reference Count: 1
Registered Events: (none)
Number Of Arrays: 0
Number Of Components: 0
Number Of Tuples: 0
Locality: 0
NumberOfConsumers: 0
ExtentTranslator: (0x83d2fa8)
MaximumNumberOfPieces: -1
Number Of Points: 0
Number Of Cells: 0
Cell Data:
Debug: Off
Modified Time: 552
Reference Count: 1
Registered Events: (none)
Number Of Arrays: 0
Number Of Components: 0
Number Of Tuples: 0
Copy Flags: ( 1 1 1 1 1 )
Scalars: (none)
Vectors: (none)
Normals: (none)
TCoords: (none)
Tensors: (none)
Point Data:
Debug: Off
Modified Time: 553
Reference Count: 1
Registered Events: (none)
Number Of Arrays: 0
Number Of Components: 0
Number Of Tuples: 0
Copy Flags: ( 1 1 1 1 1 )
Scalars: (none)
Vectors: (none)
Normals: (none)
TCoords: (none)
Tensors: (none)
Bounds:
Xmin,Xmax: (1e+38, -1e+38)
Ymin,Ymax: (1e+38, -1e+38)
Zmin,Zmax: (1e+38, -1e+38)
Compute Time: 0
Release Data: Off
ScalarType: 10
NumberOfScalarComponents: 1
Spacing: (1, 1, 1)
Origin: (0, 0, 0)
Dimensions: (0, 0, 0)
Increments: (0, 0, 0)
Extent: (0, -1, 0, -1, 0, -1)
WholeExtent: (0, -1, 0, -1, 0, -1)
What gives?
The reason for trying to get rid of the file accessing, was performance. I thought that I could assign the data directly with the python-list (as my code above shows) without the triple loop. If that's not the case, then the file reading is probably the best solution after all.
Regards,
Øyvind Knudsen
----- Original Message -----
From: REGAT-BARREL Aurélien <arbvtk at yahoo.fr>
Date: Wed, 11 Feb 2004 20:13:21 +0100 (CET)
To: Oeyvind Knudsen <knudsen at operamail.com>, vtkusers at vtk.org
Subject: Re: [vtkusers] Basic question, vtkStructuredPoints
> Hello,
> So you want to include a vtk data file directly in your Python source code and build a vtkStructuredGrid from scratch ? Why ?
> I work on a project in Python which used to build its own vtkStructuredPoints from scratch in Python.
> Here is the code equivalent for you :
> spData = vtkStructuredPoints()
> spData.SetDimensions( 81, 81, 1 )
> spData.SetOrigin( 0, 0, 0 )
> spData.SetSpacing( 1, 1, 1 )
> scalars = vtkUnsignedCharArray()
> for z in range( 0, 1 ) :
> for y in range( 0, 81 ) :
> for x in range( 0, 81 ) :
> val = getValue( x, y, z )
> scalars.InsertNextValue( val )
> spData.GetPointData().SetScalars( scalars )
>
> It should work (you must replace getValue( x, y, z ) by the right thing) but in my opinion you should not use this method, since it is very slow because each VTK object method call cost is high du to the wrapping layer between VTK (C++) and your Python code. That's why the program I am working on was very slow and why I moved this code to C++. If your really want to do it in Python, I recommend your to create a temporary vtk file, to read it as you are currently doing and then delete it in order to keep good performances. But maybe that if you dont use a bigger object than your 81x81x1 grid it will be done enough fast for your need.
> Hope it helps.
>
> Aurélien REGAT-BARREL
>
>
> Oeyvind Knudsen <knudsen at operamail.com> wrote:
> Hi!
>
> I'm using VTK to visualize a surface from a data file using the vtkStructuredPointsReader in Python. But from now the data should be passed directly from within the program, i.e. without using files or readers at all. Currently the code for making the surface looks like this:
>
> reader = vtkStructuredPointsReader()
> reader.SetFileName("data.vtk")
>
> geometry = vtkImageDataGeometryFilter()
> geometry.SetInput(reader.GetOutput()) #
> warp = vtkWarpScalar()
> warp.SetInput(geometry.GetOutput())
> warp.XYPlaneOff()
> warp.SetScaleFactor(100)
>
> merge = vtkMergeFilter()
> merge.SetGeometry(warp.GetOutput())
> merge.SetScalars(reader.GetOutput()) #
>
> smoother = vtkSmoothPolyDataFilter()
> smoother.SetInput(merge.GetOutput())
> smoother.SetNumberOfIterations(50)
>
> mapper = vtkPolyDataMapper()
> mapper.SetInput(smoother.GetOutput())
> mapper.SetScalarRange(self.minData,self.maxData)
> mapper.ImmediateModeRenderingOff()
>
> surface = vtkLODActor()
> surface.SetMapper(mapper)
>
> self.renderer.AddActor(surface)
> (+ some axis stuff)
>
> The data is in this format:
>
> # vtk DataFile Version 2.0
> data
> ASCII
> DATASET STRUCTURED_POINTS
> DIMENSIONS 81 81 1
> ORIGIN 0 0 0
> SPACING 1 1 1
> POINT_DATA 6561
> SCALARS Scalars0 float 1
> LOOKUP_TABLE default
> 0.0624595315954 0.0686842278186 0.0747777522745 (+ many more numbers)
>
> So, instead of using this file as a source I now get a python list of the data in to my visualization method. But I can't seem to get the vtkStructuredPoints object constructed in a proper way as my surface will no longer appear. I start with this:
>
> spData = vtkStructuredPoints()
> spData.SetDimensions(81, 81, 1)
>
> But how do I get the scalar values into spData so that spData and reader.GetOutput() (from the current code) yields the same resulting object? The goal is to replace all the occurences of reader.GetOutput() from the above code with just spData.
>
> Regards,
> Øyvind Knudsen
>
>
> ---------------------------------
> Yahoo! Mail : votre e-mail personnel et gratuit qui vous suit partout !
Créez votre Yahoo! Mail
--
_____________________________________________________________
Web-based SMS services available at http://www.operamail.com.
>From your mailbox to local or overseas cell phones.
Powered by Outblaze
More information about the vtkusers
mailing list