[Paraview] Custom plugin reader with time series

[Mike Jackson]

I think at some point when I started writing custom readers there was  
a statement somewhere that basically said starting with  
vtkUnstructuredGridAlgorithm (or any of the other *Algorithms) was  
appropriate for a custom reader so that is why I selected that as my  
superclass. Also, I needed more/different functionality from my  
readers AND my actual file readers do NOT depend on VTK so they can  
be stand alone if needed.

-- 
Mike Jackson


On May 11, 2008, at 4:31 AM, Dominik Szczerba wrote:

> OK so this is basically about reading the series myself explicitly.  
> But one thing is not clear to me: I am deriving my readers from  
> vtkDataReader, after UnstructuredGridReader and  
> StructuredPointsReader, who can read time series somehow, so this  
> functionality must be already in somewhere (upstream). There is no  
> explicit time series handling in those classes and yet they work,  
> so why mine do not? I can see that you do derive your reader from  
> vtkUnstructuredGridAlgorithm, and not vtkDataReader, why? I wonder  
> if I really have to re-implement it and if there is no simpler way  
> to achieve the goal, like taking advantage of some existing  
> functionality.
> Thanks, Dominik
>
> Mike Jackson wrote:
>> Take a look at <http://titanium.imts.us/viewvc/Task_4/ 
>> PVDislocation/src/DislocationReaders/ 
>> vtkPrdsMultiOutDislocationReader.cxx?view=markup>
>>  to see how I did a time series reader.
>> Basically in RequestInformation  you will need to determine the the
>> range of times that your data covers, probably by opening each  
>> file or
>> some other means. Then set
>>     double timeRange[2];
>>     timeRange[0] = lowestTimeValue
>>     timeRange[1] = highesetTimeValue
>>     outInfo->Set(vtkStreamingDemandDrivenPipeline::TIME_RANGE(),
>> timeRange, 2);
>> Also, you will need to have the following in your header:
>>    vtkSetMacro(TimeStep, int);
>>    vtkGetMacro(TimeStep, int);
>>  int GetNumberOfTimeSteps();
>> Now, down in the RequestData() Method you can get the requested time
>> step from the
>> pipeline and then open and read the data from the proper data file.
>> int tsLength = outInfo->Length 
>> (vtkStreamingDemandDrivenPipeline::TIME_STEPS());
>>   double* steps = outInfo->Get 
>> (vtkStreamingDemandDrivenPipeline::TIME_STEPS());
>>   // Check if a particular time was requested.
>>   if(outInfo->Has 
>> (vtkStreamingDemandDrivenPipeline::UPDATE_TIME_STEPS()))
>>   {
>>     // Get the requested time step. We only supprt requests of a  
>> single time
>>     // step in this reader right now
>>     double *requestedTimeSteps =
>> outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_TIME_STEPS());
>>     this->TimeValue = requestedTimeSteps[0];
>>     // find the first time value larger than requested time value
>>     // this logic could be improved
>>     int cnt = 0;
>>     while (cnt < tsLength-1 && steps[cnt] < this->TimeValue)
>>       {
>>       cnt++;
>>       }
>>     this->ActualTimeStep = cnt;
>>   }
>>   if (this->TimeStep > -1)
>>   {
>>     this->ActualTimeStep = this->TimeStep;
>>   }
>>   if (this->ActualTimeStep >= this->TimeStepRange[0] &&
>> this->ActualTimeStep <= this->TimeStepRange[1]) {
>>     vtkSmartPointer<DislocationReader> reader =
>> vtkSmartPointer<DislocationReader>::New();
>>     reader->SetFileName(this->FileName);
>>     reader->SetTimeStep(this->ActualTimeStep);
>>     //reader->SetInformationVector(outputVector);
>>     reader->SetFileOffsets(this->FileOffsets);
>>     reader->read();
>>     vtkUnstructuredGrid* grid;
>>     grid = reader->GetDislocations();
>>     dislocations->ShallowCopy(grid);
>>    // dislocations->SetBlock(0, grid);    // Block 0 is the  
>> Dislocation Data
>>     grid = reader->GetSimulationBox();
>>     simBox->ShallowCopy(grid);
>>     //dislocations->SetBlock(1, grid); // Block 1 is the  
>> Simulation Limits
>>   } else {
>>       std::cout << "vtkPrdsMultiOutDislocationReader: Timestep was  
>> out
>> of Range: " << this->ActualTimeStep << std::endl;
>>       std::cout << "vtkPrdsMultiOutDislocationReader: Timestep  
>> Range:"
>> << this->TimeStepRange[0] << " -> " << this->TimeStepRange[1] <<
>> std::endl;
>>       return 0;
>>   }
>> This code is specific to my case where I have a whole separate reader
>> for my data where I feed it the name of the file to read and then  
>> tell
>> it to read the file and get the output. This may also be the case for
>> you also.
>> Hope some of the helps.
>> Mike
>> On Sat, May 10, 2008 at 6:03 AM, Dominik Szczerba
>> <domi at vision.ee.ethz.ch> wrote:
>>> Hi,
>>> I have successfully implemented a reader for my data as a PV  
>>> plugin. It
>>> loads separate files correctly, refuses, however, to read the  
>>> whole series
>>> (file_01.h5, file_02.h5, etc.). How do I go about achieving the  
>>> same effect
>>> as the native readers to have a series as transient data?
>>> Thanks for any hints.
>>> --
>>> Dominik Szczerba, Ph.D.
>>> Computer Vision Lab CH-8092 Zurich
>>> http://www.vision.ee.ethz.ch/~domi
>>> _______________________________________________
>
> -- 
> Dominik Szczerba, Ph.D.
> Computer Vision Lab CH-8092 Zurich
> http://www.vision.ee.ethz.ch/~domi