Transcript Scientific Visualization using VTK Robert Putnam [email protected] Scientific Visualization with VTK – Fall 2010

Scientific Visualization using VTK
Robert Putnam
[email protected]
Scientific Visualization with VTK – Fall 2010
Outline
•
Introduction
• VTK overview
• VTK data geometry/topology
• Case study
• Interactive session
Scientific Visualization with VTK – Fall 2010
Introduction
• 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).
*Adapted from The ParaView
Tutorial, Moreland
Scientific Visualization with VTK – Fall 2010
VTK
Visualization Toolkit
– Open source
– Set of object-oriented class libraries for visualization and data analysis
– Several language interfaces
•
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–
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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 pipeline
Filters(s)
data/geometry/topology
Scientific Visualization with VTK – Fall 2010
---------------------
Source(s)
Output
graphics
VTK terminology/model
Filter
data/geometry/topology
Scientific Visualization with VTK – Fall 2010
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Source
Mapper
Renderer
graphics
VTK terminology/model
“Scene"
Filter
DataObject
ProcessObject
data/geometry/topology
Scientific Visualization with VTK – Fall 2010
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Source/
Reader
Lights, Camera
Actor
Mapper
Renderer
RenderWindow
graphics
Pipeline -> Sample Code
vtkStructuredGridReader reader
reader SetFileName "density.vtk"
Reader
reader Update
vtkContourFilter iso
iso SetInputConnection [reader GetOutputPort]
Filter
iso SetValue 0 .26
vtkPolyDataMapper isoMapper
isoMapper SetInputConnection [iso GetOutputPort]
vtkActor isoActor
isoActor SetMapper isoMapper
vtkRenderer ren1
Mapper
Actor
Renderer
ren1 AddActor isoActor
vtkRenderWindow renWin
renWin AddRenderer ren1
renWin SetSize 500 500
renWin Render
Scientific Visualization with VTK – Fall 2010
RenderWindow
TCL v. C++
•
TCL
vtkStructuredGridReader reader
reader SetFileName "density.vtk"
reader Update
vtkContourFilter iso
iso SetInputConnection [reader GetOutputPort]
iso SetValue 0 .26
•
C++
vtkStructuredGridReader *reader = vtkStructuredGridReader::New();
reader->SetFileName("density.vtk");
reader->Update();
vtkContourFilter *iso = vtkCountourFilter::New();
iso->SetInputConnection(reader->GetOutputPort());
iso->SetValue(0, .26);
Scientific Visualization with VTK – Fall 2010
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. Topology
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Geometry of a dataset ~= points
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Topology ~= connections among points, which
define cells

So, what’s the topology here?
Scientific Visualization with VTK – Fall 2010
VTK – Geometry v. Topology
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Scientific Visualization with VTK – Fall 2010
VTK – Geometry v. Topology
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Scientific Visualization with VTK – Fall 2010
VTK – Geometry v. Topology
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Scientific Visualization with VTK – Fall 2010
VTK – Geometry v. Topology
or
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Scientific Visualization with VTK – Fall 2010
Geometry/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 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

Data is discrete
– Interpolation functions generate data values in between known points
Scientific Visualization with VTK – Fall 2010
Examples 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)

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
Examples of Cell Types
Scientific Visualization with VTK – Fall 2010
Data 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 Points
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
000111111000
000111111000
000111111000
000111111000
000111111000
Scientific Visualization with VTK – Fall 2010
File Format – Structured Points
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
000111111000
000111111000
000111111000
000111111000
000111111000
Scientific Visualization with VTK – Fall 2010
File Format – Structured Points
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
001100
001100
001100
001100
Scientific Visualization with VTK – Fall 2010
File Format – Structured Points
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
001100
001100
001100
001100
Scientific Visualization with VTK – Fall 2010
Structured Points – Tcl code
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
Scientific Visualization with VTK – Fall 2010
Structured Points – Tcl code (cont.)
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 .
Scientific Visualization with VTK – Fall 2010
Work flow – Case Study

BU Space Physics simulation
 Meteor trails in the ionosphere
 Data wrangling:
 Consolidate datafiles (from parallel code), create single binary
datafile
# vtk DataFile Version 3.0
 Add VTK header:
output of reassemble.c
BINARY
DATASET STRUCTURED_POINTS
ORIGIN 0.0 0.0 0.0
SPACING 1.0 1.0 1.0
DIMENSIONS 512 64 128
POINT_DATA 4194304
SCALARS plasma float
LOOKUP_TABLE default
Scientific Visualization with VTK – Fall 2010
Work flow – Case Study

Use Tcl for fast development/testing:
vtkStructuredPointsReader reader
reader SetFileName "opp.vtk"
reader Update
vtkContourFilter iso
iso SetInputConnection \
[reader GetOutputPort]
iso SetValue 0 0.1
. . .
Scientific Visualization with VTK – Fall 2010
Work flow – Case Study

Add gaussian filter :
vtkImageGaussianSmooth gaussian
gaussian SetInputConnection [reader GetOutputPort]
gaussian SetDimensionality 3
gaussian SetRadiusFactor 1
vtkContourFilter iso
iso SetInputConnection \
[gaussian GetOutputPort]
iso SetValue 0 0.1
. . .
Scientific Visualization with VTK – Fall 2010
Work flow – Case Study

Add more isosurfaces :
vtkContourFilter iso
iso SetInputConnection [gaussian GetOutputPort]
iso SetValue 0 1.0
iso SetValue 1 0.5
iso SetValue 2 0.1
Scientific Visualization with VTK – Fall 2010
Work flow – Case Study

Port to C++, add cutplane, transparency :
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);
Scientific Visualization with VTK – Fall 2010
Work 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 - UI
Unix Shell:
katana:% cd ~/materials
katana:% vtk cone2.tcl
Scientific Visualization with VTK – Fall 2010
Keyboard shortcuts
j – joystick (continuous) mode
t – trackball mode
c –camera move mode
a –actor move mode
left mouse – rotate x,y
ctrl - left mouse – rotate z
middle mouse –pan
right mouse –zoom
r –reset camera
s/w –surface/wireframe
u –command window
e –exit
Scientific Visualization with VTK – Fall 2010
Code – cone2.tcl
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
Scientific Visualization with VTK – Fall 2010
Exercise
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
Scientific Visualization with VTK – Fall 2010
Code – Exercise
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
...
Scientific Visualization with VTK – Fall 2010
VTK - Readers

Image and Volume Readers
–
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
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 - Readers

Polygonal Data Readers
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
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)
–
–
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–
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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 Grid
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
...
Scientific Visualization with VTK – Fall 2010
Clipping, 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 – Clipping
Editor: clipping.tcl
vtkStructuredGridReader 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
Scientific Visualization with VTK – Fall 2010
Code – Cutplane/Slicing
Editor: cutplane.tcl
vtkStructuredGridReader 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
Scientific Visualization with VTK – Fall 2010
Code – ExtractGrid
Editor: extract.tcl
vtkStructuredGridReader 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
Scientific Visualization with VTK – Fall 2010
Color 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 Mapping
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
...
Scientific Visualization with VTK – Fall 2010
Exercise
* Change the number of colors in colormap
* Reverse the Hue Range
* Change the Scalar Range
mapper SetScalarRange 0.0 0.7
Scientific Visualization with VTK – Fall 2010
Contouring

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)
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
...
Scientific Visualization with VTK – Fall 2010
Code – Contour (isosurface)
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
...
Scientific Visualization with VTK – Fall 2010
Scalar 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 Generation
Editor: hawaii.color.tcl
vtkPolyDataReader 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
Scientific Visualization with VTK – Fall 2010
Scalar generation – Color Map
Editor: hawaii.color2.tcl
vtkLookupTable 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
Scientific Visualization with VTK – Fall 2010
Hedgehogs

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 – HedgeHogs
Editor: hedgehog.tcl
vtkStructuredGridReader 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
Scientific Visualization with VTK – Fall 2010
Oriented 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 Glyphs
Editor: glyph.tcl
vtkArrowSource 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]
Scientific Visualization with VTK – Fall 2010
Field 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 Lines
Streamlines
• 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 – Streamlines
Editor: streamLines.tcl
vtkPointSource 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
Scientific Visualization with VTK – Fall 2010
Code – Streamtubes
Editor: streamTubes.varyRadius.tcl
vtkPointSource 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
Scientific Visualization with VTK – Fall 2010
Annotation
Annotation
– used for annotating visualization
– VTK
• vtkScalarBarActor
• vtkTextMapper
• vtkScaledTextActor
Scientific Visualization with VTK – Fall 2010
Code – colorBar
Editor: colorBar.tcl
vtkStructuredGridReader 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
Scientific Visualization with VTK – Fall 2010
VTK - Writers

Polygonal Data Writers
–
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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
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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 Images
Saving Images
– common formats:
• jpeg (lossy)
• png (lossless)
• postscript
• tiff (lossless)
– VTK
•vtkWindowToImageFilter
•vtkRenderLargeImage
Scientific Visualization with VTK – Fall 2010
Code – Saving Images
Editor: output.tcl
renWin 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
Scientific Visualization with VTK – Fall 2010
VTK - Resources

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/

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Texts
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The Visualization Toolkit, 4th Edition, Kitware, Inc, 2006.
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The VTK User’s Guide, 5th Edition, Kitware, Inc, 2006.
Websites
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www.vtk.org
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www.kitware.com
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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
Scientific Visualization with VTK – Fall 2010
Questions?

Tutorial survey:
- http://scv.bu.edu/survey/fall10tut_survey.html
Scientific Visualization with VTK – Fall 2010