Beginning Filters Python

Introduction

ParaView filters

This usecase shows a user how to use filters to modify the display of data.

All filter examples assume that the user starts with a new model. To start over, go to the menu item Edit → Delete All, and then re-open your data.

Data is opened by going to File → Open. Example data files can be found on the ParaView web page at http://www.paraview.org.

Clip filter

<source lang="python"> >>> from paraview.simple import * >>> reader = ExodusIIReader(FileName=".../can.ex2") >>> Show(reader) >>> Render() </source> <source lang="python"> >>> clipFilter = Clip(reader) >>> Hide(reader) >>> Show(clipFilter) >>> Render() </source> <source lang="python">

1. get camera

>>> camera = GetActiveCamera() >>> camera.GetPosition()

1. figure out where you are

>>> camera.SetPosition(4.156,4.0,-36.29) >>> camera.Elevation(30) >>> camera.GetPosition() (4.1560389876787056, 19.261366923548998, -32.200729057625857) >>> camera.SetPosition(4.15603, 30, -35) >>> Render() </source> <source lang="python">

1. we can see what's going on a little better

>>> clipFilter.UseValueAsOffset = 1 >>> clipFilter.Value = 5 >>> Render() </source> <source lang="python">

1. let's change the orientation of the clip filter

>>> clipFilter.ClipType.Normal [1.0, 0.0, 0.0] >>> clipFilter.ClipType.Origin [0.0, 0.0, 0.0]

1. reset the offset value of the clip to 0

>>> clipFilter.Value = 0 >>> clipFilter.ClipType.Normal = [0,0,1] >>> Render() </source> <source lang="python"> >>> clipFilter.Value = -3 >>> Render() </source> <source lang="python"> >>> clipFilter.InsideOut = 1 >>> Render() </source>

Slice filter

Getting the camera on this one can be right since the slices are invisible from certain angles. <source lang="python"> >>> from paraview.simple import * >>> reader = ExodusIIReader(FileName=".../Data/can.ex2") >>> sliceFilter = Slice(reader) >>> Show(sliceFilter) >>> Render() >>> camera = GetActiveCamera() >>> camera.Elevation(30) >>> camera.SetPosition(-51.3152,4.987,-9.64218) >>> Render() </source> <source lang="python"> >>> sliceFilter.SliceType.Normal [1.0, 0.0, 0.0]

1. the origin of the slice needs to be moved to see slices in the Y-plane

>>> sliceFilter.SliceType.Origin = [2.5,5,0] >>> sliceFilter.SliceType.Normal = [0,1,0] >>> Render() </source> <source lang="python"> >>> sliceFilter.SliceType.Normal = [0,0,1] >>> Render() </source> <source lang="python">

>>> sliceFilter.SliceType.Normal = [0,1,0] >>> sliceFilter.SliceOffsetValues [] >>> sliceFilter.SliceOffsetValues = [-4,-3.11,-2.22,-1.33,-0.44,0.44,1.33,2.22,3.11,4] >>> Render()

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Glyph filter

>>> from paraview.simple import * >>> reader = ExodusIIReader(FileName="/home/tmjung/Desktop/ParaViewData/Data/can.ex2") >>> Show(reader) >>> camera = GetActiveCamera() >>> camera.SetPosition(0,5,-45) >>> camera.Elevation(30)

1. Change the can to be wireframe so we can see the glyphs

>>> dp1 = GetDisplayProperties(reader) >>> dp1.Representation = 'Wireframe'

>>> glyphFilter = Glyph(reader)

1. We won't see much if we don't move forward in the animation a little bit

>>> tsteps = reader.TimestepValues >>> view = GetActiveView() >>> view.ViewTime = tsteps[20]

>>> glyphFilter.Vectors ['POINTS', 'DISPL']

1. Set the glyphs to use the acceleration vectors and adjust scale factor

>>> glyphFilter.Vectors = 'ACCL' >>> glyphFilter.SetScaleFactor 1.0 >>> glyphFilter.SetScaleFactor = 0.0000002 </source> <source lang="python">

1. Set the glyphs to use the velocity vectors and adjust scale factor

>>> glyphFilter.Vectors = 'VEL' >>> glyphFilter.SetScaleFactor = 3e-4

1. Let's add some color

>>> dp2 = GetDisplayProperties(glyphFilter) >>> glyphFilter.PointData[:] [Array: PedigreeNodeId, Array: DISPL, Array: VEL, Array: ACCL, Array: GlobalNodeId, Array: GlyphVector]

1. We'll color by velocity so use that array.

>>> vel = glyphFilter.PointData[2] >>> vel.GetName() 'VEL' >>> vel.GetRange() (-2479.9521484375, 1312.5040283203125) >>> dp2.LookupTable = MakeBlueToRedLT(-2479.9521,1312.5) >>> dp2.ColorAttributeType = 'POINT_DATA' >>> dp2.ColorArrayName = 'VEL' >>> Render()

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Cell to Point/ Point to Cell filters

These filters are used to convert a data set from being cell data to being point data and vice versa. This is sometimes useful if a filter requires one type of data, and a user only has the other type of data. An example would be using can.exo. You cannot get a contour of EQPS directly, since EQPS is cell data and contour only works on points. Use filter Cell Data to Point Data first, then call contour.

Acknowledgements

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.