John Biddiscombe

1
Working with Time in ParaView

• John Biddiscombe
• CSCS
• Swiss National Supercomputing Centre

2
Contents

• Data Formats for time-dependent data
• Overview of GUI controls
• Animation Controls
• Connection between GUI and internals
• Comparative Visualization mode
• Temporal Pipeline Overview
• Time Dependent Filters (vtkTemporalXXX)
• Manipulating Time in Filters (C code)
• Gotchas Bugs
• Future Plans

3

• Data Import

4
Formats Supported

• Exodus (used by several US research facilities)
• vtkPVDReader (vtk XML Collection)
• filename.pvd Filename-00.vtu/vti/vtp etc
• vtkFileSeriesReader
• vtkXML Reader
• PolyData, UnstructuredGrid, StructuredGrid,
  ImageData, RectilinearGrid, Multiblock,
  Heirarchical etc.
• Legacy VTK files with 001, 002, 003 filenames
• Ensight (case files, ASCII/Binary data)
• OpenFOAM, SpyPlot, Phasta, STL, MFIX (untested by
  me)
• Xdmf (extensible data model format)
• XML light data with geometry/time information
  inside
• Hdf5 heavy big data containing scalars/fields
• (CSCS) custom readers include netCDF, H5Part
  (from CSCS web site)

5
Vtk (XML based) file format

• VTK Collection - Easy to create by hand if
  necessary
• A General purpose holder for vtk XML files of all
  types
• vtuunstructured, vtppolydata, vtrrectilinear,
  vtiimagedata
• Each individual file can be binary/text,
  compressed or not
• ltVTKFile type"Collection" version"0.1"
  byte_order"LittleEndian"gt
• ltCollectiongt
• ltDataSet timestep"0.01" group"" part"0"
  file"Foo_001.vtu"/gt
• ltDataSet timestep0.02" group"" part"0"
  fileFoo_002.vtu"/gt
• ltDataSet timestep0.03" group"" part"0"
  fileFoo_003.vtu"/gt
• lt/Collectiongt
• lt/VTKFilegt
• The VTK Collection is in fact a generic holder
  for MultiBlock composite datasets which can store
  time information too.
• The vtkXMLReader family is responsible for
  loading this kind of data.
• User can use vtkXML_xxx_Writer to write N time
  steps of any kind of data and then add a little
  XML meta data to describe it.
• Caveat pvd time collections are not working
  well in parallel (NxM split of blocks)

6
.pvd versus File List

• .pvd collection is a true Time compatible holder
  for data
• Time steps can be specified with real time values
• Dont need to be contiguous or equally spaced
• FileSeriesReader Selecting .vtu/p/i/etc
• simple but efficient way of loading time series
• One step per file
• Cant specify true time values
• vtkFileSeriesReader is clever
• Load one get one
• Load .ext, get time series
• No C changes required to reader

7
vtkFileSeriesReader make reader time aware

• ltFileSeriesReaderProxy
• name"XMLUnstructuredGridReader"
• class"vtkFileSeriesReader"
• label"XML Unstructured Grid reader"
• file_name_method"SetFileName"gt
• ltDocumentation
• short_helpblah blah
• long_helpditto"gt
• The XML Unstructured Grid reader reads the VTK
  XML unstructured grid data file format. The
  standard extension is .vtu.
• This reader also supports file series.
• lt/Documentationgt

8
FileSeriesReader (slide 2)

• Put details of your existing reader in
  ExposedProperties
• ltSubProxygt
• ltProxy name"Reader"
• proxygroup"internal_sources"
• proxyname"XMLUnstructuredGridReaderCore"gt
• lt/Proxygt
• ltExposedPropertiesgt
• ltProperty name"CellArrayInfo" /gt
• ltProperty name"CellArrayStatus" /gt
• ltProperty name"PointArrayInfo" /gt
• ltProperty name"PointArrayStatus" /gt
• lt/ExposedPropertiesgt
• lt/SubProxygt

9
FileSeriesReader (slide 3)

• ltStringVectorProperty name"FileName"
• clean_command"RemoveAllFileNames"
• command"AddFileName"
• animateable"0"
• number_of_elements"0"
• repeat_command"1"gt
• ltFileListDomain name"files"/gt
• ltDocumentationgt
• The list of files to be read by the reader. If
  more than 1 file is specified, the reader will
  switch to file series mode in which it will
  pretend that it can support time and provide 1
  file per time step.
• lt/Documentationgt
• lt/StringVectorPropertygt

10
FileSeriesReader (slide 4)

• The part which makes it time aware
• ltDoubleVectorProperty
• name"TimestepValues"
• information_only"1"gt
• ltTimeStepsInformationHelper/gt
• ltDocumentationgt
• Available timestep values.
• lt/Documentationgt
• lt/DoubleVectorPropertygt
• lt/FileSeriesReaderProxygt

11
Old and New Time in ParaView

• In PV2.x Time was generally animated by changing
  the TimeStep value of a reader (or filter
  sometimes).
• In PV3.x Time is an information variable/object
  passed down the pipeline which makes it possible
  for filters to modify time before passing it to
  their source. For this reason, the GUI sets the
  time inside the Rendering/Mapping code and not
  via a TimeStep variable.
• Some older (custom) readers may still have a
  TimeStep variable, but this is being phased out
  and its use is not encouraged unless you are
  trying to do something a bit special (see later
  slides).

12
Reader XML
For any reader If you omit this (this is all you
need in the XML) Then you wont see the time
information.
ltDoubleVectorProperty name"TimestepValues" infor
mation_only"1"gt ltTimeStepsInformationHelper/gt ltDo
cumentationgt Available timestep
values. lt/Documentationgt lt/DoubleVectorPropertygt
It connects the TIME_STEPS key to the GUI
13
The old method (xml for reference)

• ltIntVectorProperty
• name"TimeStep" command"SetTimeStep"
• number_of_elements"1" default_values"0"
• animateable"0"
• information_property"TimestepValues"gt
• ltIntRangeDomain name"range"gt
• ltRequiredPropertiesgt
• ltProperty name"TimeStepRangeInfo"
  function"Range"/gt
• lt/RequiredPropertiesgt
• lt/IntRangeDomaingt
• ltDocumentationgt Set the current timestep.
  lt/Documentationgt
• lt/IntVectorPropertygt
• And for convenience we usually provided a
  GetTimestepValues(vector)

14
C Reader RequestInformation

• Scan files/data structures and build a
  list/vector/array of times
• Set TIME_STEPS for discrete time data (most
  readers really)
• outInfo-gtSet(
• vtkStreamingDemandDrivenPipelineTIME_STEPS(),
• this-gtTimeStepValues0, this-gtTimeStepValues.si
  ze())
• Set TIME_RANGE if continuous, but can also be set
  for discrete
• double timeRange2
• timeRange0 this-gtTimeStepValues.front()
• timeRange1 this-gtTimeStepValues.back()
• outInfo-gtSet(
• vtkStreamingDemandDrivenPipelineTIME_RANGE(),
  timeRange, 2)

15
C Reader RequestData

• Find the correct time step (index into array of
  step values)
• if (
• outInfo-gtHas(vtkStreamingDemandDrivenPipelineUPD
  ATE_TIME_STEPS()))
• // usually only one actual step requested
• double requestedTimeValue outInfo-gtGet(vtkStre
  amingDemandDrivenPipelineUPDATE_TIME_STEPS())0
  
• this-gtActualTimeStep vtkstdfind_if(
• this-gtTimeStepValues.begin(),
  this-gtTimeStepValues.end(),
• vtkstdbind2nd( WithinTolerance( ),
  requestedTimeValue ))
• - this-gtTimeStepValues.begin()

16
C Reader RequestData

• Time stamp the output DataObject using
  DATA_TIME_STEPS
• output-gtGetInformation()-gtSet(vtkDataObjectDATA
  _TIME_STEPS(), requestedTimeValue, 1)
• Nothing bad happens if you dont But filters
  which use the time information wont get what
  they need.
• vtkTemporalPathLineFilter builds lists of data
  times for each frame and joins the dots.
• You can read the UPDATE_TIME_STEPS key, but it
  might not be the same, and is strictly only
  present during RequestUpdateExtent

17

• GUI Controls
• Animating with Time

18
Animation GUI Controls
Time value displayed in toolbar Time step
mode user can change step Sequence mode user
can change time freely VCR style toolbar has
play controls (play, step forward/back, jump to
start/end) Data with Time support shows the
timesteps in the information tab. (Lacks ability
to click on timestep and jump to it) Animation
control has settings for time stepping and
keyframes Abort button to stop movie generation
not obvious
19
Time Modes in Animation Inspector

• Snap to TimeSteps
• When you click play the animation will begin at
  whatever time step you are on and continue until
  it either reaches the end (or is stopped
  manually).
• When stopped the animation will continue from
  where it left off if restarted.
• Each frame played represents a single time step
  of the input data
• There is no need to set any keyframes or specify
  any particular property to animate.
• The Track selection is used to select or create
  keyframes

20
Time Modes in Animation Inspector

• Snap to TimeSteps Warning
• When dataset 1 is loaded it may have time values
• 0, 1, 2, 3, ..N
• When dataset 2 is loaded it may have time values
• 0.5, 1.5, 2.5, 3.5, ..M
• Playing an animation in Snap To TimeSteps mode
  will traverse ALL KNOWN Timesteps which means
• 0, 0.5, 1, 1.5, 2, 2.5 ..max(M,N)
• This can cause unexpected results!
• Future time support should allow you to Snap to
  active pipeline steps so that only the times
  exported for a particular dataset/filter will be
  traversed. (In development).
• Fix Use Sequence mode and lock the start and
  end times to prevent changes

21
Time Modes in Animation Inspector

• Sequence Mode
• The start and end times correspond to the max and
  min values of time in the data you loaded.
• If you manually change the start/end times you
  can Lock the new times this prevents them
  being reset to the default start/end times if new
  data is loaded.
• Animation will now ignore the Time steps present
  in the data and use interval(end/start)/(numFrame
  s-1)
• This is frequently NOT WHAT YOU WANT

22
Time Modes in Animation Inspector
Worked example interval(end/start)/(numFrames-1)
60.001424 - 50.001424 10 Num Frames 10 We
should get our original time steps back (1s per
step) In fact we get 10/(numFrames-1)
1.11111111s/frame Need to use 11 frames to get
0,1,2,3,4,5,6,7,8,9,10 Note In the some
versions of PV3 selecting time values which are
not exactly the same as those present will
produce no update. It should snap to the nearest
time step, but does not. See SnapToTimeSteps for
a fix.
23
Time Modes in Animation Inspector

• Real Time
• Animates using the Wall time
• Not always useful for the majority of
  filters/data sources that we use
• Useful to animate as fast as we can if data was
  stored with time representing a real clock value
  and we wish to play back data in real time.
• In this mode not all times may be displayed. Some
  will be skipped or some may be on screen for
  ages.
• Could also be very handy for integrating
  generators of data (eg sensor equipment) into the
  gui and displaying the real time update of the
  sensor (no examples of this yet though)

24

• Comparative visualization

25
Comparative View Inspector

• Allows MxN array of views on the same data
• Allows a variable to be changed along the X axis.
• Wrong - limitation ltisgt used to be that time must
  be between 0.0-1.0 for the view to operate

Solution TemporalShiftScale with 1/N scale
factor (or use Normalize flag set if present in
CVS)
26
Same Data at multiple T
Uses Time steps of selected object Avoid
mismatched time display in same
window. FilmStrip uses X Comparative
XY Works, but patience required
27
Comparative viz Summary

• Much easier than
• Creating multiple windows manually
• Setting up Shift/Scale
• Instantiating Pipelines
• Setting view/display properties
• Can also use other plot styles.

28

• Time Dependent Algorithms/Filters
• Pipeline Introduction

29
Pipeline Introduction

• The pipeline is demand driven with
• data flowing downstream
• Information flowing up and down stream
• In PV3 Time is part of the Information flow.

Data
filter(s)
Data source
Display/GUI Renderer
UPDATE_TIME_STEPS
Information
30
How does it work

• How does the pipeline actually fit together
• All filters are connected together by Executives
  which receive information from downstream (and
  upstream) and decide
• Are the data inputs valid
• Are the data outputs valid
• Is everything else valid
• Has anything changed since I last updated

In PV3 Time is passed as information and the
executives can LOOP portions of the pipeline over
multiple time steps This means that filters can
request multiple time steps This enables us to
implement Time Dependent Algorithms
31
Pipeline Looping

• vtkTemporalDataSet
• When the pipeline is looped to generate multiple
  time steps, the executive generates a dataset
  collection
• The collection is passed to the temporal
  algorithm
• The algorithm can request any number of time
  steps
• But usually 2 (linear interpolation)
• In order to make looping work, some information
  keys are used internally

32
Information Keys

• During Updates, the pipeline makes 4 request
  passes
• DataObject, Information, UpdateExtent, Data
• Keys exported by time aware sources
• TIME_RANGE (continuous), TIME_STEPS (discrete)
• Time aware reader will declare N steps 0.0, 0.1,
  0.2..etc
• Keys used during requests
• UPDATE_TIME_STEPS (Filter says I want these)
• Interpolator says I need times 0.1 and 0.2 for
  example
• Keys set during execution
• DATA_TIME_STEPS (Source says I made these)
• Data generator says I generated times 0.1 and 0.2
  
• Keys used internally by executives
• REQUIRES_TIME_DOWNSTREAM (looping will be needed)
• CONTINE_EXECUTING (multiple passes inside
  algorithm)

33

• Time Dependent Algorithms/Filters
• Interpolation

34
(Linear) Interpolation

• vtkTemporalInterpolator
• Linearly interpolates between 2 time steps
• When Time T.5 is requested it requests times T
  and T1
• 2 Modes of Operation
• Continuous
• Discrete
• Continuous Mode
• DiscreteTimeStepInterval0.0
• Filter generates no TIME_STEPS on output just a
  TIME_RANGE
• GUI can request any time between min/max
• Discrete Mode
• DiscreteTimeStepIntervalgt0
• Filter generates (max-min)/DiscreteTimeStepInterva
  l steps
• GUI sees discrete data with new TIME_STEPS values

35
(Linear) Interpolation

• Continuous mode
• Input data (left) has N discrete time steps
• Output data (right) has no time steps
• It does report a TIME_RANGE
• So the GUI knows that any time between min/max
  can be requested

36
Interpolation Continuous mode
Data Courtesy David Graham, Plymouth UK.
37
(Linear) Interpolation

• Discrete mode
• Example
• DiscreteTimeStepInterval0.01
• New time steps are generated and the output data
  looks like it has 10x as many time steps.
• Note that no interpolation of the data has been
  performed yet, only when something is actually
  rendered/requested will the interpolation take
  place.

38
Interpolation Discrete mode
39
(Linear) Interpolation

• What can be interpolated
• Any Dataset which does not change topology
  between time steps
• Point positions are interpolated
• Connectivity (cells are copied)
• Point Data is interpolated
• Cell Data is interpolated
• ImageData/PolyData/Rectilinear/Unstructured
• All can be interpolated if cell connectivity and
  number of cells remains the same
• MultiBlock/MultiGroup/Heirarchical/AMR
• If the tree structure remains the same between
  time steps and the individual leaves satisfy
  above conditions
• Other interpolation methods could be added

40
Fixing Problems with the interpolator

• Discrete mode
• Given an input with N time steps, but a few are
  accidentally missing (lost of never generated)
• Set DiscreteTimeStep Interval to the original
  time step size (say 0.1 or 0.01 etc)
• Data saved every Nth frame to save IO time.
• Output now seems to be exactly the same as the
  input except that the steps that were missing
  from the input are recreated using interpolation
  when requested on the output
• Animate using Snap To TimeSteps mode
• Animation will look like intended original

41
Problem Fixing Example (Interpolation)
Before Missing data, low sampling Problems for
particle tracer
After Lovely
42

• Temporal DataSet Cache

43
Interpolation Use a cache

• If animation from 0-gtt is performed using a
  TemporalInterpolator, the interpolator will
  request 2 time steps each time it updates
• Interpolating at 0.1 spacing between 2 steps
  causes
• Step 0 Step 1 Output Step 0.1
• Step 0 Step 1 Output Step 0.2 Each step N
  times!
• Step 0 Step 1 Output Step 0.3
• Use a TemporalDataSetCache to store 2 timesteps
  and prevent this repeated re-execution of the
  pipeline

44
Branching Time Use a cache

• Its not just the filter delivering the data at
  T, but the whole upstream pipeline that is
  protected
• Consider the case where a pipeline branches and
  different T values are requested. The cache
  prevents updates from one section propagating too
  far upstream and forcing the other branch to be
  re-executed needlessly.

Simple filter(s) (no special time requirements)
Temporal DataSetCache
TemporalFilter (requires multiple time steps,
e.g.. Particle tracer)
Display/GUI Renderer
Data source (time aware)
TemporalShiftScale (modifies time values)
45
Branching Time Caution in the GUI

• When different values to T are visible/manipulated
  
• Only display the leaf nodes of the pipeline
• Rendering intermediate portions can trigger
  unwanted/confusing updates

Display/GUI Renderer
Simple filter(s) (no special time requirements)
UPDATE_TIME_STEPS
UPDATE_TIME_STEPS
Temporal DataSetCache
TemporalFilter (requires multiple time steps,
e.g.. Particle tracer)
Display/GUI Renderer
Data source (time aware)
TemporalShiftScale (modifies time values)
46
Multiple Inputs

• Related Cautionary Note 1

47
Multiple Inputs

• Time dependent filters with multiple inputs
• Trigger updates on all inputs
• Particle Tracer is one example

Avoid this. Save Seeds if possible
48

• Temporal Snap to TimeSteps

49
SnapToTimeSteps Example
50
Time Display Side note

• Source Time Source
• Takes time from the UPDATE_TIME_STEPS
• Actually it takes it directly from the view which
  is responsible for setting the key on the
  filter/output
• Filter-gtTemporal-gtAnnotate Time
• Takes its time from DATA_TIME_STEPS
• Which is the actual time step output from the
  filter
• The two might not always be the same (snap to
  timestep for example)

51

• Time Shifting

52
Temporal Shift Scale

• Changes time between the input and output of a
  filter
• Can be used to compare the same data at 2
  different values of T (though the comparative viz
  view is easier to use in some ways)
• Invaluable for combining different datasets with
  different T values
• See example pipeline below
• Tout PreShift TinScale PostShift
• NB. ve PostShift produces ve delay of output
  time
• seems the wrong way around
• but time 0 is now time N, so it takes N seconds
  to get to it

53
Temporal Shift Scale

• Pre-Shift -50.0014
• Scale 1/10
• Post-Shift 3

Before 50-0014 - 60.0014
After 3.0 4.0
54
Developer Tip Hiding bad time data

• In RequestData
• if (outInfo-gtHas(vtkStreamingDemandDrivenPipeline
  UPDATE_TIME_STEPS()))
• double requestedTimeValue outInfo-gt
  Get(vtkStreamingDemandDrivenPipelineUPDATE_TIME_
  STEPS())0
• if (requestedTimeValueltthis-gtTimeStepValues.front
  () requestedTimeValuegtthis-gtTimeStepValues.bac
  k())
• this-gtTimeOutOfRange 1
• output-gtGetInformation()-gtSet(vtkDataObjectD
  ATA_TIME_STEPS(), requestedTimeValue, 1)
• if (this-gtTimeOutOfRange this-gtMaskOutOfTimeRan
  geOutput)
• // don't do anything, just return success
• return 1

55
Developer Tip Normalize Time

• In RequestInformation
• if (this-gtNormalizeToUnitTime
  this-gtTimeStepValues.size()gt0)
• double t1 this-gtTimeStepValues.front()
• double t2 this-gtTimeStepValues.back()
• double t3 (t2-t1)gt0 ? (1.0/(t2-t1)) 1.0
• for (unsigned int i0 iltthis-gtTimeStepValues.
  size() i)
• double t this-gtTimeStepValuesi
• this-gtTimeStepValuesi t3(t-t1)
• Then everything comes out 0,1
• Feature might be available in ShiftScale.
  Regional Variations ?

56
Comparative Vis (using Time shift)

• Time shift Interpolation Trails
• 3 time dependent features in 1 go

57
Temporal Shift Scale

• Periodic Mode
• Turns N time steps spanning t time units into
• NT steps spanning Tt units
• Periodic End Correction
• If simulation steps are 0,1,2N-1 and N-1 is
  identical to 0
• Periodic end correction OFF 0,1,2N-1,1,2,3..N
  -1
• Otherwise 0,1,2N-1,1,2,3..N-1 causes
  duplicated step
• If simulation steps are 0,1,2N-1 and N-1 is
  different from 0
• Periodic end correction On
• Otherwise 0,1,2N-1,0,2,3..N-1 causes
  duplicated step

58
Periodic example

• 2 Separate Datasets
• one 40 steps
• one 80 steps
• Duration 1s (approx)
• Need 5hours
• 8036005 1.44E6
• Tried 10,000 Periods in ParaView (1 day?)
• Need a better model!

59
Particle Tracer Pipeline (one nasty example)
DataSet 1
Temporal Cache
Particle Tracer
PathLines
Interpolate
DataSet 2
Shift Scale
Temporal Cache
Seeds 1
GUI
Seeds 2
60
Periodic Time Resampling Time Shift
61
Side Note XML for Temporal Support

• ltSourceProxy name"TemporalSnapToTimeStep"
• class"vtkTemporalSnapToTimeStep"
• label"Temporal Snap-to-Time-Step"gt
• ltInputProperty name"Input" command"SetInputCon
  nection"gt
• ltProxyGroupDomain name"groups"gt
• ltGroup name"sources"/gt
• ltGroup name"filters"/gt
• lt/ProxyGroupDomaingt
• ltDataTypeDomain name"input_type"
  composite_data_supported"1"gt
• ltDataType value"vtkDataObject"/gt
• lt/DataTypeDomaingt
• lt/InputPropertygt
• Will change in future no way of saying
  DataType PolyData Temporal_required

62

• Particle Tracer
• TemporalStreamTracer

63
Particle Tracing
All Inputs must have same vector field Multiple
Multiblock Inputs supported (Temporal Required)
Meshes can be dynamic Parallel operation If
input dataset has N time steps Particle tracer
will generate N-1 output steps Output step 0 time
value corresponds to input step 0,1
time Nothing can be generated until 1 time period
has passed Seed points are supplied as separate
inputs Use SetTimeStep to combat odd time input
combinations
64
Request Update Extent

• for (int i0 iltnumInputs i)
• vtkInformation inInfo inputVector0-gtGetInfo
  rmationObject(i)
• // our output timestep T is timestep T1 in the
  source
• // so output inputTimeStepsT,
  inputTimeStepsT1
• inInfo-gt Set(vtkStreamingDemandDrivenPipelineU
  PDATE_TIME_STEPS(),
• this-gtInputTimeValuesthis-gtActualTimeStep,
  2)
• vtkDebugMacro(ltlt "requested 2 time values "
• ltlt this-gtInputTimeValuesthis-gtActualTimeStep
  ltlt " "
• ltlt this-gtInputTimeValuesthis-gtActualTimeStep
  1)

65
Particle Tracing (setup example)
Source (seedpoints) LineSource 100 points Time
Step resolution Leave as 1 this can be used to
scale time if the input time was not stored
correctly (e.g. it goes 0N but should be 0.1 0.2
0.3 etc) Time Step (output index) Set to zero
initially this will request steps, (0,1) from
the input and the time actually corresponds to
T1 (but it will be the 0th step on the output)
66
Particle Tracing
Force re-injection every 1 or 2 time
steps Particles will be injected at the seed
points every N steps Input vectors Usually a
velocity field, but could be another Initial
Integration step Used by Runge-Kutta integration
to make incremental velocity field
approximations Can be smaller but 0.25 usually
OK Static Seeds - Static Mesh Force
optimizations GEOMETRY_NOT_MODIFIED (work in
progress)
67
Particle Tracing

• Ignore pipeline time
• This is very important the particle tracer
  generates less output steps than the input (-1)
  and so we cannot (yet) use the default animation
  controls due to bug mentioned earlier.
• NB. This works now, but the comment is useful
• We therefore instruct the particle tracer to
  ignore pipeline time and instead animate the
  Timestep property from 0 to N-2 (if the input has
  N steps, the Particle tracer has N-1 steps
  output, so we go from 0 to N-2 to get the correct
  number)
• Particle filename (not shown)
• An option to store particles to disk will be
  included at a future date.

68
Side Note Ignore Pipeline Time

• if (this-gtIgnorePipelineTime)
• if (this-gtTimeStepltthis-gtOutputTimeValues.size())
  
• requestedTimeValue this-gtOutputTimeValuesth
  is-gtTimeStep
• else
• requestedTimeValue this-gtOutputTimeValues.ba
  ck()
• this-gtActualTimeStep this-gtTimeStep
• vtkDebugMacro(ltlt "SetTimeStep
  requestedTimeValue
• ltlt requestedTimeValue ltlt " ActualTimeStep "
• ltlt this-gtActualTimeStep)
• else
• the usual stuff to get requested time

69
Particle Tracing

• To generate animation of particles
• Use Sequence Mode Animation
• Use N-1 Frames (because there will be N-1 steps
  generated this data had 51 steps on the input
  indexed as 0-50), so we use 50 frames for output
• Create a Keyframe on ParticleTracer TimeStep.
• Set Keyframe index 0
• Time to start time 0.0 here
• Value to TimeStep 0
• Set Keyframe index 1
• Time to end time 7.99 in this example
• Value to 49 (last index 51-2)
• Animation can now be played/saved as movie

70
Francis Turbine
71

• PathLineFilter

72
Pathline Filter

• Connects to output of Particle tracer
• Can be used on any dataset with points (not just
  particles)
• Now supports selection of subset
• But needs to be updated to use vtkSelection type
• Uses Ids from selection dataset to choose points
  for line construction
• Is not strictly a vtkTemporalXXX filter because
  it does not loop time
• Listents to DATE_TIME_STEPS on input and builds
  list from that
• See other slides for example of usage

73

• Plotting Data
• over Time

74
Plotting of data over Time

• Iterative operation
• Extract one or more variables at a point or
  region over time
• GUI not driving the iteration process
• Filter manually sets CONTINUE_EXECUTING
• Exodus Data supports FAST_PATH_FOR_TEMPORAL_DATA
• And uses
• FAST_PATH_OBJECT_TYPE, (POINT, CELL, EDGE, FACE)
• FAST_PATH_ID_TYPE, (INDEX, GLOBAL)
• FAST_PATH_OBJECT_ID, (vtkIdType)
• vtkSelections ? For future use?

75
Temporal Statistics
76
Temporal Statistics

• Computes
• Mean
• Min
• Max
• Standard Deviation
• More can be added
• Can take time!

77
SelectionTime
78
Selection over time

• The same procedure can be used to query a
  particle over all available time
• Extract Selection over time filter builds a
  spreadsheet of values for the selected IDs over
  all time steps
• NB Cant set a sub region of time using the
  animation controls yet, but this feature will be
  coming
• Selection tutorial should cover possible types
• Cell/Point/Global IDs can be used here

79
Plot Selection over time
Which Point to display
Which field(s)
80
Plot Selection over Time
81
Animations with Non simple time
82
How to animate a slice on a time-dependent dataset

• Problem
• When I try to animate, time changes as well as
  the slice
• I cant set time start/end to constants and then
  animate slice alone
• ParaView hangs because of zero increment
• Trying to fool it with tiny increments is not
  safe.
• Show animation viewer and double click time track
• Now animate the slice or other property using
  sequence mode
• And keyframes to suit.

83
Demo 1

• How to animate a slice, and then animate the
  data?

Double click on these tracks
84
Setup a slice keyframe

• Create Slice offset keyframe
• Animate a slice 50 frames one way
• 50 frames back again
• Note that extents are /- 1.5 3
• Check values when adding keyframes

85
Change the Time track itself

• Double click Time track
• Time is variable
• It has its own keyframes
• Fix time from frames 1-50
• Animate time from 50 to 5060

86
Sequence mode coordination

• Make sure the Animation inspector has the same
  information as the animation viewer
• And.the keyframes
• When you add/remove them, or adjust the start/end
  time, they get rescaled
• Could do with a locking keyframe time option
  here
• The time here should be thought of as frames

87
Demo 2

• Fixed, forward and reverse time in one animation

Animation (frame) time
View (data) time
We need tracks per dataset to combine different
sources
88
Animate Camera from Python

• phi range(0, 360)
• for i in phi
• view.CameraPosition 2400math.cos(imath.pi2
  .0/360), 2400math.sin(imath.pi2.0/360), 300
• view.StillRender()
• imgfile "/path/to/snapshot.03d.png" i
• view.WriteImage(imgfile, "vtkPNGWriter", 1)
• To be Continued
• Python versions of TimeAnimationCue, Scene, View
• Exercise for the reader (Utkarsh) recreate
  fancy time animations in Python

89
Conclusion

• Few Time dependent filters in ParaView so far
• But
• Already powerful tool for animations/analysis
• Animation improvements and time step handling
  will make it hard to beat in terms of features
  and flexibility