Scientific Visualization using VTKScientific Visualization using VTK
Robert Putnam
Scientific Visualization with VTK – Fall 2010
OutlineOutline
• Introduction• VTK overview• VTK data geometry/topology• Case study• Interactive session
Scientific Visualization with VTK – Fall 2010
IntroductionIntroduction
Scientific Visualization with VTK – Fall 2010
*Adapted from The ParaView Tutorial, Moreland
• Visualization: converting raw data to a form that is viewable and understandable to humans.
• Scientific visualization: specifically concerned with data that has a well-defined representation in 2D or 3D space (e.g., from simulation mesh or scanner).
VTKVTK
Visualization Toolkit– Open source
– Set of object-oriented class libraries for visualization and data analysis
– Several language interfaces• C++
• Tcl
• Java
• Python
– Portable (MS Windows, Linux, OSX)
– Active developer community
– Good documentation available, free and otherwise
– Professional support services available from Kitware
Scientific Visualization with VTK – Fall 2010
Generic visualization pipelineGeneric visualization pipeline
Scientific Visualization with VTK – Fall 2010
Source(s) Filters(s) Output - - - - - - - - - - - - - - - - - - - - -
data/geometry/topology graphics
VTK terminology/modelVTK terminology/model
Scientific Visualization with VTK – Fall 2010
Source Filter Renderer
- - - - - - - - - - - - - - - - - - - - -
data/geometry/topology graphics
Mapper
VTK terminology/modelVTK terminology/model
Scientific Visualization with VTK – Fall 2010
Source/ Reader
Filter Renderer
- - - - - - - - - - - - - - - - - - - - -
data/geometry/topology graphics
Mapper
“Scene"
Lights, Camera
DataObject ProcessObject
Actor
RenderWindow
Pipeline -> Sample CodePipeline -> Sample CodevtkStructuredGridReader reader
reader SetFileName "density.vtk"
reader Update
vtkContourFilter iso
iso SetInputConnection [reader GetOutputPort]
iso SetValue 0 .26
vtkPolyDataMapper isoMapper
isoMapper SetInputConnection [iso GetOutputPort]
vtkActor isoActor
isoActor SetMapper isoMapper
vtkRenderer ren1
ren1 AddActor isoActor
vtkRenderWindow renWin
renWin AddRenderer ren1
renWin SetSize 500 500
renWin Render
Scientific Visualization with VTK – Fall 2010
Reader
Filter
Mapper
Actor
Renderer
RenderWindow
TCL v. C++TCL v. C++
• TCL
• C++
Scientific Visualization with VTK – Fall 2010
vtkStructuredGridReader reader
reader SetFileName "density.vtk"
reader Update
vtkContourFilter iso
iso SetInputConnection [reader GetOutputPort]
iso SetValue 0 .26
vtkStructuredGridReader *reader = vtkStructuredGridReader::New();reader->SetFileName("density.vtk");reader->Update();
vtkContourFilter *iso = vtkCountourFilter::New();iso->SetInputConnection(reader->GetOutputPort());iso->SetValue(0, .26);
Coding tip of the day!Coding tip of the day!
• Google “VTK class list”, or• Go to:
http://www.vtk.org/doc/nightly/html/annotated.html
Scientific Visualization with VTK – Fall 2010
VTK – Geometry v. TopologyVTK – Geometry v. Topology
Geometry of a dataset ~= points
Scientific Visualization with VTK – Fall 2010
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
Topology ~= connections among points, which define cells
So, what’s the topology here?
VTK – Geometry v. TopologyVTK – Geometry v. Topology
Scientific Visualization with VTK – Fall 2010
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0,0 1,0 2,0 3,0
VTK – Geometry v. TopologyVTK – Geometry v. Topology
Scientific Visualization with VTK – Fall 2010
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
or
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
VTK – Geometry v. TopologyVTK – Geometry v. Topology
Scientific Visualization with VTK – Fall 2010
or
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
or
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
VTK – Geometry v. TopologyVTK – Geometry v. Topology
Scientific Visualization with VTK – Fall 2010
or
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
or
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
or
0,1 1,1 2,1 3,1
0,0 1,0 2,0 3,0
Geometry/Topology StructureGeometry/Topology Structure
Structure may be regular or irregular– Regular (structured)
• need to store only beginning position, spacing, number of points
• smaller memory footprint per cell (topology can be generated on the fly)
• examples: image data, rectilinear grid, structured grid
– Irregular (unstructured)• information can be represented more densely where it changes quickly
• higher memory footprint (topology must be explicitly written) but more freedom
• examples: polygonal data, unstructured grid
Scientific Visualization with VTK – Fall 2010
Characteristics of DataCharacteristics of Data
Data is organized into datasets for visualization– Datasets consist of two pieces
• organizing structure– points (geometry)
– cells (topology)
• data attributes associated with the structure
– File format derived from organizing structure
Scientific Visualization with VTK – Fall 2010
Data is discrete– Interpolation functions generate data values in between known points
Examples of Dataset TypesExamples of Dataset Types
Structured Points (Image Data)– regular in both topology and geometry
– examples: lines, pixels, voxels
– applications: imaging CT, MRI
Rectilinear Grid– regular topology but geometry only partially
regular
– examples: pixels, voxels
Structured Grid (Curvilinear)– regular topology and irregular geometry
– examples: quadrilaterals, hexahedron
– applications: fluid flow, heat transfer
Scientific Visualization with VTK – Fall 2010
Examples of Dataset Types (cont)Examples of Dataset Types (cont)
Polygonal Data– irregular in both topology and geometry
– examples: vertices, polyvertices, lines, polylines, polygons, triangle strips
Unstructured Grid – irregular in both topology and geometry
– examples: any combination of cells
– applications: finite element analysis, structural design, vibration
Scientific Visualization with VTK – Fall 2010
Data AttributesData Attributes
Data attributes associated with the organizing structure– Scalars
• single valued
• examples: temperature, pressure, density, elevation
– Vectors• magnitude and direction
• examples: velocity, momentum
– Normals • direction vectors (magnitude of 1) used for shading
– Texture Coordinates• used to map a point in Cartesian space into 1, 2, or 3D texture space
• used for texture mapping
– Tensors • 3x3 only
• examples: stress, strain
Scientific Visualization with VTK – Fall 2010
File Format – Structured PointsFile Format – Structured Points
Scientific Visualization with VTK – Fall 2010
Editor structured-points.vtk:
# vtk DataFile Version 3.0
first dataset
ASCII
DATASET STRUCTURED_POINTS
DIMENSIONS 3 4 5
ORIGIN 0 0 0
SPACING 1 1 2
POINT_DATA 60
SCALARS temp-point float
LOOKUP_TABLE default
0 0 0 1 1 1 1 1 1 0 0 0
0 0 0 1 1 1 1 1 1 0 0 0
0 0 0 1 1 1 1 1 1 0 0 0
0 0 0 1 1 1 1 1 1 0 0 0
0 0 0 1 1 1 1 1 1 0 0 0
File Format – Structured PointsFile Format – Structured Points
Scientific Visualization with VTK – Fall 2010
Editor structured-points.vtk:
# vtk DataFile Version 3.0
first dataset
ASCII
DATASET STRUCTURED_POINTS
DIMENSIONS 3 4 5
ORIGIN 0 0 0
SPACING 1 1 2
POINT_DATA 60
SCALARS temp-point float
LOOKUP_TABLE default
0 0 0 1 1 1 1 1 1 0 0 0
0 0 0 1 1 1 1 1 1 0 0 0
0 0 0 1 1 1 1 1 1 0 0 0
0 0 0 1 1 1 1 1 1 0 0 0
0 0 0 1 1 1 1 1 1 0 0 0
File Format – Structured PointsFile Format – Structured Points
Scientific Visualization with VTK – Fall 2010
Editor structured-points2.vtk:
# vtk DataFile Version 3.0
first dataset
ASCII
DATASET STRUCTURED_POINTS
DIMENSIONS 3 4 5
ORIGIN 0 0 0
SPACING 1 1 2
CELL_DATA 24
SCALARS temp-cell float
LOOKUP_TABLE default
0 0 1 1 0 0
0 0 1 1 0 0
0 0 1 1 0 0
0 0 1 1 0 0
File Format – Structured PointsFile Format – Structured Points
Scientific Visualization with VTK – Fall 2010
Editor structured-points2.vtk:
# vtk DataFile Version 3.0
first dataset
ASCII
DATASET STRUCTURED_POINTS
DIMENSIONS 3 4 5
ORIGIN 0 0 0
SPACING 1 1 2
CELL_DATA 24
SCALARS temp-cell float
LOOKUP_TABLE default
0 0 1 1 0 0
0 0 1 1 0 0
0 0 1 1 0 0
0 0 1 1 0 0
Structured Points – Tcl codeStructured Points – Tcl code
Scientific Visualization with VTK – Fall 2010
Editor structured-points.tcl:vtkStructuredPointsReader reader
reader SetFileName "structured-points.vtk"
reader Update
vtkLookupTable lut
lut SetNumberOfColors 2
lut SetTableValue 0 0.0 0.0 1.0 1
lut SetTableValue 1 1.0 0.0 0.0 1
vtkDataSetMapper mapper
mapper SetInputConnection [reader GetOutputPort]
mapper SetLookupTable lut
vtkActor actor
actor SetMapper mapper
[actor GetProperty] EdgeVisibilityOn
[actor GetProperty] SetLineWidth 2
Structured Points – Tcl code (cont.)Structured Points – Tcl code (cont.)
Scientific Visualization with VTK – Fall 2010
Editor structured-points.tcl:vtkRenderer ren1
ren1 AddActor actor
ren1 SetBackground 0.5 0.5 0.5
vtkRenderWindow renWin
renWin AddRenderer ren1
renWin SetSize 500 500
vtkRenderWindowInteractor iren
iren SetRenderWindow renWin
iren Initialize
wm withdraw .
Work flow – Case StudyWork flow – Case Study
BU Space Physics simulation Meteor trails in the ionosphere Data wrangling:
Consolidate datafiles (from parallel code), create single binary datafile
Add VTK header:
Scientific Visualization with VTK – Fall 2010
# vtk DataFile Version 3.0output of reassemble.cBINARYDATASET STRUCTURED_POINTSORIGIN 0.0 0.0 0.0SPACING 1.0 1.0 1.0DIMENSIONS 512 64 128POINT_DATA 4194304SCALARS plasma floatLOOKUP_TABLE default
Work flow – Case StudyWork flow – Case Study
Use Tcl for fast development/testing:
Scientific Visualization with VTK – Fall 2010
vtkStructuredPointsReader reader reader SetFileName "opp.vtk" reader Update
vtkContourFilter iso iso SetInputConnection \[reader GetOutputPort] iso SetValue 0 0.1
. . .
Work flow – Case StudyWork flow – Case Study
Add gaussian filter :
Scientific Visualization with VTK – Fall 2010
vtkImageGaussianSmooth gaussian gaussian SetInputConnection [reader GetOutputPort] gaussian SetDimensionality 3 gaussian SetRadiusFactor 1 vtkContourFilter iso iso SetInputConnection \ [gaussian GetOutputPort] iso SetValue 0 0.1
. . .
Work flow – Case StudyWork flow – Case Study
Add more isosurfaces :
Scientific Visualization with VTK – Fall 2010
vtkContourFilter iso iso SetInputConnection [gaussian GetOutputPort] iso SetValue 0 1.0 iso SetValue 1 0.5 iso SetValue 2 0.1
Work flow – Case StudyWork flow – Case Study
Port to C++, add cutplane, transparency :
Scientific Visualization with VTK – Fall 2010
vtkPlane *plane = vtkPlane::New(); plane->SetOrigin(256,2,63.5); plane->SetNormal(0,1,0);
vtkCutter *planeCut = vtkCutter::New(); planeCut->SetInputConnection(reader->GetOutputPort()); planeCut->SetCutFunction(plane);
Work flow – Case StudyWork flow – Case Study
Change color map, use script to loop over *.vtk, generate multiple jpegs, read into Adobe Premiere, produce animation:
Scientific Visualization with VTK – Fall 2010
VTK – Getting Started - UIVTK – Getting Started - UI
Scientific Visualization with VTK – Fall 2010
Unix Shell:
katana:% cd ~/materials
katana:% vtk cone2.tcl
Keyboard shortcutsKeyboard shortcuts
Scientific Visualization with VTK – Fall 2010
j – joystick (continuous) modet – trackball mode
c –camera move modea –actor move mode
left mouse – rotate x,yctrl - left mouse – rotate zmiddle mouse –panright mouse –zoom
r –reset cameras/w –surface/wireframeu –command windowe –exit
Code – cone2.tclCode – cone2.tcl
Scientific Visualization with VTK – Fall 2010
Editor cone2.tcl:vtkConeSource cone
cone SetResolution 100
vtkPolyDataMapper coneMapper
coneMapper SetInput [cone GetOutput]
vtkActor coneActor
coneActor SetMapper coneMapper
[coneActor GetProperty] SetColor 1.0 0.0 0.0
vtkRenderer ren1
ren1 SetBackground 0.0 0.0 0.0
ren1 AddActor coneActor
vtkRenderWindow renWin
renWin SetSize 500 500
renWin AddRenderer ren1
vtkRenderWindowInteractor iren
iren SetRenderWindow renWin
iren Initialize
ExerciseExercise
Scientific Visualization with VTK – Fall 2010
Editor: cone3.tcl
Add coneActor2, and color it green. (Copy
coneActor, and make appropriate changes.
Remember to add the new actor to the
render window [near the end of the
“pipeline”].)
Optional: to rotate, scale and set the position
away from the origin, use the following:
coneActor2 RotateZ 90
coneActor2 SetScale 0.5 0.5 0.5
coneActor2 SetPosition -1.0 0.0 0.0
Code – ExerciseCode – Exercise
Scientific Visualization with VTK – Fall 2010
Editor: cone3.tcl
. . .
vtkActor coneActor2
coneActor2 SetMapper coneMapper
[coneActor2 GetProperty] SetColor 0.0 1.0 0.0
coneActor2 RotateZ 90
coneActor2 SetScale 0.5 0.5 0.5
coneActor2 SetPosition -1.0 0.0 0.0
. . .
ren1 AddActor coneActor
ren1 AddActor coneActor2
. . .
VTK - ReadersVTK - Readers Image and Volume Readers
– vtkStructuredPointsReader - read VTK structured points data files
– vtkSLCReader - read SLC structured points files
– vtkTIFFReader - read files in TIFF format
– vtkVolumeReader - read image (volume) files
– vtkVolume16Reader - read 16-bit image (volume) files
Structured Grid Readers– vtkStructuredGridReader - read VTK structured grid data files
– vtkPLOT3DReader - read structured grid PLOT3D files
Rectilinear Grid Readers– vtkRectilinearGridReader - read VTK rectilinear grid data files
Unstructured Grid Readers– vtkUnstructuredGridReader - read VTK unstructured grid data files
Scientific Visualization with VTK – Fall 2010
VTK - ReadersVTK - Readers Polygonal Data Readers
– vtkPolyDataReader - read VTK polygonal data files
– vtkBYUReader - read MOVIE.BYU files
– vtkMCubesReader - read binary marching cubes files
– vtkOBJReader - read Wavefront (Maya) .obj files
– vtkPLYReader - read Stanford University PLY polygonal data files
– vtkSTLReader - read stereo-lithography files
– vtkUGFacetReader - read EDS Unigraphic facet files
Image and Volume Readers (add’l)– vtkBMPReader - read PC bitmap files
– vtkDEMReader - read digital elevation model files
– vtkJPEGReader - read JPEG files
– vtkImageReader - read various image files
– vtkPNMReader - read PNM (ppm, pgm, pbm) files
– vtkPNGRReader - read Portable Network Graphic files
Scientific Visualization with VTK – Fall 2010
File Format – Structured GridFile Format – Structured Grid
Scientific Visualization with VTK – Fall 2010
Editor density.vtk:# vtk DataFile Version 3.0
vtk output
ASCII
DATASET STRUCTURED_GRID
DIMENSIONS 57 33 25
POINTS 47025 float
2.667 -3.77476 23.8329 2.94346 -3.74825 23.6656 3.21986 -3.72175 23.4982
3.50007 -3.70204 23.3738 3.9116 -3.72708 23.5319 4.1656 -3.69529 23.3312
. . .
POINT_DATA 47025
SCALARS Density float
LOOKUP_TABLE default
0.639897 0.239841 0.252319 0.255393 0.252118 0.246661 0.240134 0.234116 0.229199
0.225886 0.224268 0.224647 0.231496 0.246895 0.26417 0.27585 0.278987 0.274621
. . .
VECTORS Momentum float
0 0 0 13.753 -5.32483 -19.964 42.3106 -15.57 -43.0034
64.2447 -13.3958 -46.2281 73.7861 -4.83205 -36.3829 88.3374 6.23797 -22.8846
. . .
Clipping, Cutting, SubsamplingClipping, Cutting, Subsampling
Selection Algorithms - Clipping
• can reveal internal details of surface
• VTK - vtkClipDataSet
- Cutting/Slicing• cutting through a dataset with a surface
• VTK - vtkCutter
- Subsampling• reduces data size by selecting a subset of
the original data
• VTK - vtkExtractGrid
Scientific Visualization with VTK – Fall 2010
Code – ClippingCode – Clipping
Scientific Visualization with VTK – Fall 2010
Editor: clipping.tclvtkStructuredGridReader reader
reader SetFileName “density.vtk”
reader Update
vtkPlane plane
eval plane SetOrigin [[reader GetOutput] GetCenter]
plane SetNormal -0.287 0 0.9579
vtkClipDataSet clip
clip SetInputConnection [reader GetOutputPort]
clip SetClipFunction plane
clip InsideOutOn
vtkDataSetMapper clipMapper
clipMapper SetInputConnection [clip GetOutputPort]
eval clipMapper SetScalarRange [[reader GetOutput] GetScalarRange]
vtkActor clipActor
clipActor SetMapper clipMapper
Code – Cutplane/SlicingCode – Cutplane/Slicing
Scientific Visualization with VTK – Fall 2010
Editor: cutplane.tclvtkStructuredGridReader reader
reader SetFileName “density.vtk”
reader Update
vtkPlane plane
eval plane SetOrigin [[reader GetOutput] GetCenter]
plane SetNormal -0.287 0 0.9579
vtkCutter planeCut
planeCut SetInputConnection
[reader GetOutputPort] planeCut SetCutFunction plane
vtkPolyDataMapper cutMapper
cutMapper SetInputConnection [planeCut GetOutputPort]
eval cutMapper SetScalarRange [[reader GetOutput] GetScalarRange]
vtkActor cutActor
cutActor SetMapper cutMapper
Code – ExtractGridCode – ExtractGrid
Scientific Visualization with VTK – Fall 2010
Editor: extract.tclvtkStructuredGridReader reader
reader SetFileName “density.vtk”
reader Update
vtkExtractGrid extract
extract SetInputConnection [reader GetOutputPort]
extract SetVOI -1000 1000 -1000 1000 7 10
extract SetSampleRate 1 1 1
extract IncludeBoundaryOn
vtkDataSetMapper mapper
mapper SetInputConnection [extract GetOutputPort]
eval mapper SetScalarRange [[reader GetOutput] GetScalarRange]
vtkActor extractActor
extractActor mapper
Color MappingColor Mapping
Scalar Algorithms– Color Mapping
• maps scalar data to colors
• implemented by using scalar values as an index into a color lookup table
• specify a HSVA (Hue-Saturation-Value-Alpha) ramp and then generate the colors in the table by using linear interpolation into the HSVA space.
– VTK • vtkLookupTable
• vtkDataSetMapper
Scientific Visualization with VTK – Fall 2010
Code – Color MappingCode – Color Mapping
Scientific Visualization with VTK – Fall 2010
Editor: colormap.numcolors.tcl
. . .
vtkLookupTable lut
lut SetNumberofColors 16
lut SetHueRange 0.0 0.667
lut Build
vtkStructuredGridReader reader
reader SetFileName “subset.vtk”
reader Update
vtkDataSetMapper mapper
mapper SetInputConnection [reader GetOutputPort]
mapper SetLookupTable lut
eval mapper SetScalarRange [[reader GetOutput] GetScalarRange]
vtkActor actor
actor SetMapper mapper
. . .
ExerciseExercise
Scientific Visualization with VTK – Fall 2010
* Change the number of colors in colormap
* Reverse the Hue Range
* Change the Scalar Range
mapper SetScalarRange 0.0 0.7
ContouringContouring
Scalar Algorithms (cont)– Contouring
• construct a boundary between distinct regions, two steps:– explore space to find points near contour
– connect points into contour (2D) or surface (3D)
• 2D contour map (isoline):– applications: elevation contours from topography, pressure contours
(weather maps) from meteorology3D isosurface:
• 3D isosurface:– applications: tissue surfaces from tomography, constant pressure or
temperature in fluid flow, implicit surfaces from math and CAD
– VTK• vtkContourFilter
Scientific Visualization with VTK – Fall 2010
Code – Contour (isoline)Code – Contour (isoline)
Scientific Visualization with VTK – Fall 2010
Editor: contour.single.tcl
. . .
vtkStructuredGridReader reader
reader SetFileName “subset.vtk”
reader Update
vtkContourFilter contour
contour SetInputConnection [reader GetOutputPort]
contour SetValue 0 0.26
vtkPolyDataMapper contourMapper
contourMapper SetInputConnection [contour GetOutputPort]
eval contourMapper SetScalarRange
[[reader GetOutput] GetScalarRange]
vtkActor contourActor
contourActor SetMapper contourMapper
. . .
Code – Contour (isosurface)Code – Contour (isosurface)
Scientific Visualization with VTK – Fall 2010
Editor: isosurface.tcl
. . .
vtkStructuredGridReader reader
reader SetFileName “density.vtk”
reader Update
vtkContourFilter iso
iso SetInputConnection [reader GetOutputPort]
iso SetValue 0 0.26
vtkPolyDataMapper isoMapper
isoMapper SetInputConnection [iso GetOutputPort]
eval isoMapper SetScalarRange [[reader GetOutput] GetScalarRange]
vtkActor isoActor
isoActor SetMapper isoMapper
. . .
Scalar GenerationScalar Generation
Scalar Algorithms (cont)– Scalar Generation
• extract scalars from part of data
• example: extracting z coordinate (elevation) from terrain data to create scalar values
– VTK• vtkElevationFilter
Scientific Visualization with VTK – Fall 2010
Code – Scalar GenerationCode – Scalar Generation
Scientific Visualization with VTK – Fall 2010
Editor: hawaii.color.tclvtkPolyDataReader hawaii
hawaii SetFileName "honolulu.vtk"
hawaii Update
vtkElevationFilter elevation
elevation SetInput [hawaii GetOutput]
elevation SetLowPoint 0 0 0
elevation SetHighPoint 0 0 1000
elevation SetScalarRange 0 1000
vtkLookupTable lut
lut SetHueRange 0.7 0
vtkDataSetMapper hawaiiMapper
hawaiiMapper SetInput [elevation GetOutput]
hawaiiMapper SetScalarRange 0 1000
hawaiiMapper SetLookupTable lut
vtkActor hawaiiActor
hawaiiActor SetMapper hawaiiMapper
Scalar generation – Color MapScalar generation – Color Map
Scientific Visualization with VTK – Fall 2010
Editor: hawaii.color2.tclvtkLookupTable lut
lut SetNumberOfColors 9
lut SetTableValue 0 0 0.4 0.8 1
lut SetTableValue 1 0.0 0.75 0.2 1
lut SetTableValue 2 0.25 0.625 0.5 1
lut SetTableValue 3 0.0 0.5 0.25 1
lut SetTableValue 4 0.5 0.365 0.0 1
lut SetTableValue 5 0.75 0.625 0.25 1
lut SetTableValue 6 1.0 0.75 0.625 1
lut SetTableValue 7 1.0 0.75 0.5 1
lut SetTableValue 8 1.0 1 1 1
HedgehogsHedgehogs
Vector Algorithms– Hedgehogs
• oriented scaled line for each vector
• scale indicates magnitude
• color indicates magnitude, pressure, temperature, or any variable
– VTK• vtkHedgeHog
Scientific Visualization with VTK – Fall 2010
Code – HedgeHogsCode – HedgeHogs
Scientific Visualization with VTK – Fall 2010
Editor: hedgehog.tclvtkStructuredGridReader reader
reader SetFileName “density.vtk”
reader Update
vtkHedgeHog hhog
hhog SetInput [reader GetOutput]
hhog SetScaleFactor 0.001
vtkPolyDataMapper hhogMapper
hhogMapper SetInput [hhog GetOutput]
hhogMapper SetLookupTable lut
eval hhogMapper SetScalarRange [[reader GetOutput] GetScalarRange]
vtkActor hhogActor
hhogActor SetMapper hhogMapper
Oriented GlyphsOriented Glyphs
Vector Algorithms (cont)– Oriented Glyphs
• orientation indicates direction
• scale indicates magnitude
• color indicates magnitude, pressure, temperature, or any variable
– VTK• vtkGlyph3D
Scientific Visualization with VTK – Fall 2010
Code – Oriented GlyphsCode – Oriented Glyphs
Scientific Visualization with VTK – Fall 2010
Editor: glyph.tclvtkArrowSource arrow
arrow SetTipResolution 6
arrow SetTipRadius 0.1
arrow SetTipLength 0.35
arrow SetShaftResolution 6
arrow SetShaftRadius 0.03
vtkGlyph3D glyph
glyph SetInput [reader GetOutputPort]
glyph SetSource [arrow GetOutputPort]
glyph SetVectorModeToUseVector
glyph SetColorModeToColorByScalar
glyph SetScaleModeToDataScalingOff
glyph OrientOn
glyph SetScaleFactor 0.2
vtkPolyDataMapper glyphMapper
glyphMapper SetInput [glyph GetOutput]
glyphMapper SetLookupTable lut
glyphMapper ScalarVisibilityOn
eval glyphMapper SetScalarRange [[reader GetOutput] GetScalarRange]
Field LinesField Lines
Vector Algorithms (cont)– Field Lines
• Fluid flow is described by a vector field in three dimensions for steady (fixed time) flows or four dimensions for unsteady (time varying) flows
• Three techniques for determining flow– Pathline (Trace)
• tracks particle through unsteady (time-varying) flow
• shows particle trajectories over time
• rake releases particles from multiple positions at the same time instant
• reveals compression, vorticity
– Streamline
• tracks particle through steady (fixed-time) flow
• holds flow steady at a fixed time
• snapshot of flow at a given time instant
– Streakline
• particles released from the same position over a time interval (time-varying)
• snapshot of the variation of flow over time
• example: dye steadily injected into fluid at a fixed point
Scientific Visualization with VTK – Fall 2010
Field LinesField LinesStreamlines
• Lines show particle flow
• VTK – vtkStreamTracer
Streamlets• half way between streamlines and glyphs
• VTK - vtkStreamTracer, vtkGlyph3D
Streamribbon• rake of two particles to create a ribbon
• VTK - vtkStreamTracer, vtkRuledSurfaceFilter
Streamtube• circular rake of particles to create a tube
• VTK - vtkStreamTracer, vtkTubeFilter
Scientific Visualization with VTK – Fall 2010
Code – StreamlinesCode – Streamlines
Scientific Visualization with VTK – Fall 2010
Editor: streamLines.tclvtkPointSource seeds
seeds SetRadius 3.0
eval seeds SetCenter [[reader GetOutput] GetCenter]
seeds SetNumberOfPoints 100
vtkRungeKutta4 integ
vtkStreamTracer streamer
streamer SetInputConnection [reader GetOutputPort]
streamer SetSourceConnection [seeds GetOutputPort]
streamer SetMaximumPropagation 100
streamer SetMaximumPropagationUnitToTimeUnit
streamer SetInitialIntegrationStepUnitToCellLengthUnit
streamer SetInitialIntegrationStep 0.1
streamer SetIntegrationDirectionToBoth
streamer SetIntegrator integ
vtkPolyDataMapper mapStreamLines
mapStreamLines SetInputConnection [streamer GetOutputPort]
eval mapStreamLines SetScalarRange [[reader GetOutput] GetScalarRange]
vtkActor streamLineActor
streamLineActor SetMapper mapStreamLines
Code – StreamtubesCode – Streamtubes
Scientific Visualization with VTK – Fall 2010
Editor: streamTubes.varyRadius.tclvtkPointSource seeds
seeds SetRadius 1.0
seeds SetNumberOfPoints 50
vtkRungeKutta4 integ
vtkStreamTracer streamer
streamer SetInputConnection [reader GetOutputPort]
streamer SetSourceConnection [seeds GetOutputPort]
. . .
vtkTubeFilter streamTube
streamTube SetInputConnection [streamer GetOutputPort]
streamTube SetRadius 0.01
streamTube SetNumberOfSides 6
# streamTube SetVaryRadiusToVaryRadiusOff
streamTube SetVaryRadiusToVaryRadiusByScalar
vtkPolyDataMapper mapStreamTube
mapStreamTube SetInputConnection [streamTube GetOutputPort]
mapStreamTube SetLookupTable lut
eval mapStreamTube SetScalarRange [[[[reader GetOutput] GetPointData] GetScalars] GetRange]
vtkActor streamTubeActor
streamTubeActor SetMapper mapStreamTube
[streamTubeActor GetProperty] BackfaceCullingOn
AnnotationAnnotation
Annotation– used for annotating visualization
– VTK• vtkScalarBarActor
• vtkTextMapper
• vtkScaledTextActor
Scientific Visualization with VTK – Fall 2010
Code – colorBarCode – colorBar
Scientific Visualization with VTK – Fall 2010
Editor: colorBar.tclvtkStructuredGridReader reader
reader SetFileName “density.vtk”
reader Update
vtkScalarBarActor scalarBar
scalarBar SetLookupTable lut
scalarBar SetTitle "Combustor Density Magnitude"
scalarBar SetNumberOfLabels 2
[scalarBar GetPositionCoordinate] SetValue 0.1 0.01
scalarBar SetOrientationToHorizontal
scalarBar SetWidth 0.8
scalarBar SetHeight 0.09
vtkRenderer ren1
vtkRenderWindow renWin
renWin AddRenderer ren1
vtkRenderWindowInteractor iren
iren SetRenderWindow renWin
ren1 AddActor streamTubeActor
ren1 AddActor outlineActor
ren1 AddActor scalarBar
ren1 SetBackground 0.5 0.5 0.5
VTK - WritersVTK - Writers Polygonal Data Writers
– vtkBYUWriter - write MOVIE.BYU files
– vtkCGMWriter - write 2D polygonal data as a CGM file
– vtkIVWriter - write Inventor files
– vtkMCubesWriter - write triangles in marching cubes format
– vtkPolyDataWriter - write VTK polygonal data files
– vtkPLYWriter - write Standford University PLY polygonal data files
– vtkSTLWriter - write stereo-lithography files
Image and Volume writers– vtkBMPwriter - write PC bitmap files
– vtkJPEGwriter - write images in JPEG format
– vtkPostscriptWriter – write image files in Postscript format
– vtkPNMwriter - write PNM (ppm, pgm, pbm) image files
– vtkPNGwriter - write image file in Portable Network Graphic format
– vtkTIFFWriter – write image files in TIFF format
– vtkStructuredPointsWriter – write a vtkStructuredPoints file
Scientific Visualization with VTK – Fall 2010
Saving ImagesSaving Images
Saving Images– common formats:
• jpeg (lossy)
• png (lossless)
• postscript
• tiff (lossless)
– VTK•vtkWindowToImageFilter
•vtkRenderLargeImage
Scientific Visualization with VTK – Fall 2010
Code – Saving ImagesCode – Saving Images
Scientific Visualization with VTK – Fall 2010
Editor: output.tclrenWin Render
vtkWindowToImageFilter w2if
w2if SetInput renWin
w2if Update
vtkRenderLargeImage renderLarge
renderLarge SetInput ren1
renderLarge SetMagnification 4
#vtkJPEGWriter writer
# writer SetInputConnection [w2if GetOutputPort]
# writer SetFileName "image.jpg"
# writer SetQuality 100
# writer Write
#vtkPNGWriter writer
# writer SetInputConnection [w2if GetOutputPort]
# writer SetFileName "image.png"
# writer Write
#vtkPostScriptWriter writer
# writer SetInputConnection [w2if GetOutputPort]
# writer SetFileName "image.ps"
# writer Write
#vtkTIFFWriter writer
# writer SetInputConnection [w2if GetOutputPort]
# writer SetFileName "image.tif"
# writer Write
vtkTIFFWriter lwriter
lwriter SetInputConnection [renderLarge GetOutputPort]
lwriter SetFileName "largeimage.tif"
lwriter Write
VTK - ResourcesVTK - Resources
Scientific Visualization with VTK – Fall 2010
IS&T tutorials– Scientific Visualization with VTK
www.bu.edu/tech/research/training/tutorials/vtk/
– VTK Examples
www.bu.edu/tech/research/training/scv-software-packages/vtk/vtk_examples/
Texts– The Visualization Toolkit, 4th Edition, Kitware, Inc, 2006.
– The VTK User’s Guide, 5th Edition, Kitware, Inc, 2006.
Websites– www.vtk.org
– www.kitware.com
– www.vtk.org/doc/release/5.4/html/classes.html
Wiki– www.vtk.org/Wiki/VTK
Mailing Lists– www.vtk.org/VTK/help/mailing.html