Paraview PTSReader misses the first point

alex_xu · February 18, 2021, 2:22am

I try to read .pts file in the Paraview.
here is one point in the test.pts file. the content is as follows:
7.75 14.28 19.08

Based on the source code here

github.com

Kitware/VTK/blob/master/IO/Geometry/vtkPTSReader.cxx

/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkPTSReader.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#include "vtkPTSReader.h"

#include "vtkCellArray.h"
#include "vtkDataArray.h"
#include "vtkDoubleArray.h"
#include "vtkFloatArray.h"

This file has been truncated. show original

There should be one point read in the Paraview.
However, there is no point at all.

Furthermore, when I have two points in the test.pts, such as
7.75 14.28 19.08
7.75 14.28 20.08

I will have only 1 point (the 2nd point) in the Paraview.

What need I do to have all points in the .pts file?
Thanks!

mwestphal · February 18, 2021, 8:37am

Please share your data.

aron.helser · February 18, 2021, 1:11pm

The comments in the source code you link make it a little more clear what is expected:
https://github.com/Kitware/VTK/blob/master/IO/Geometry/vtkPTSReader.cxx#L164
The first line of the .pts file should contain the number of points to be read.

alex_xu · February 18, 2021, 1:16pm

test1.pts (16 Bytes) test2.pts (18 Bytes)

Here are two test .pts files.
Each file has only one point.

test1.pts has point only.
test2.pts has the # of points at the first line.

alex_xu · February 18, 2021, 1:19pm

I tried both formats. You can find two test files in this thread.

Furthermore,

github.com

Kitware/VTK/blob/fb8caa82f798b8015119aed8b1db940c09dd81f7/IO/Geometry/vtkPTSReader.cxx#L181


getline(file, buffer);
// Scanf should match the integer part but not the string
int numArgs = sscanf(buffer.c_str(), "%d%s", &tempNumPts, junk);
if (numArgs == 1)
{
  numPts = static_cast<vtkTypeInt32>(tempNumPts);
  break;
}
if (numArgs != -1)
{
  // We have a file that doesn't have a number of points line
  // Instead we need to count the number of lines in the file
  // Remember we already read in the first line hence numPts starts
  // at 1
  for (numPts = 1; getline(file, buffer); ++numPts)
  {
    if (numPts % 1000000 == 0)
    {
      this->UpdateProgress(0.1);
      if (this->GetAbortExecute())
      {

It also shows that we can have points-only content.

aron.helser · February 18, 2021, 1:25pm

Cool - do you see any issue with the code?

alex_xu · February 18, 2021, 2:36pm

I just looked through the code.
The issue may be here:

github.com

Kitware/VTK/blob/fb8caa82f798b8015119aed8b1db940c09dd81f7/IO/Geometry/vtkPTSReader.cxx#L332


if (this->CreateCells)
{
  pids = new vtkIdType[targetNumPts];
}
long lastCount = 0;
for (long i = 0; i < numPts; i++)
{
  // Should we process this point?  Meaning that we skipped the appropriate number of points
  // based on the Max Number of points (onRatio) or the filtering by the read bounding box
  // OK to process based on Max Number of Points
  if (floor(i * onRatio) > lastCount)
  {
    lastCount++;
    sscanf(buffer.c_str(), "%lf %lf %lf %lf %lf %lf %lf", pt, pt + 1, pt + 2, irgb, irgb + 1,
      irgb + 2, irgb + 3);
    // OK to process based on bounding box
    if ((!this->LimitReadToBounds) || this->ReadBBox.ContainsPoint(pt))
    {
      pid = newPts->InsertNextPoint(pt);
      // std::cerr << "Point " << i << " : " << pt[0] << " " << pt[1] << " " << pt[2] << "\n";
      if (this->CreateCells)

let’s say onRatio = 1.0
when we process the first point,
lastCount = 0
i = 0
i * onRatio = 0
floor(i * onRatio) > lastCount is always false, lastCount remains 0
we miss the 1st point

however, in the following points
lastCount = 0
i = 1
i * onRatio = 1.0
floor(i * onRatio) > lastCount is true
we have the 2nd point,
lastCount becomes 1

then, i = 2, etc.

what’s more, even we set the Max Number of points
( onRatio = static_cast(this->MaxNumberOfPoints) / numPts;),
floor(i * onRatio) > lastCount doesn’t work as well IMHO.

I don’t understand why we need onRatio here,
why not use
if (this->MaxNumberOfPoints > lastCount)

But, I haven’t tested it yet. I am not very familiar with Paraview/VTK. And, my current work doesn’t allow me spend more time in debugging the vtkPTSReader. That’s the reason I posted this help-thread. Sorry about that.

alex_xu · February 25, 2021, 8:58pm

It seems that I forgot to @ you in the previous post, please take a look at my previous post.
thank you