[vtkusers] vtkOBJReader not reading the whole mesh

[Bill Lorensen]

This problem is because in given polydata the number of tcoords or normals
does not match the number of points.  The importer silently skips the
polydata.

On Dec 13, 2017 6:28 PM, "Todd Martin" <nztoddler at yahoo.com> wrote:

> I found a problem similar to this when using  vtkPolyData->SetPoints(). If
> the point coordinates were not initialised, no polygons were produced.
>
> I didn't search the code, but it seemed to me that the coordinate values
> (floats) should be explicitly set to zero when a vtkPoint object is created
> (or any other object with real values), because I presume the compiler will
> not do it automatically (unlike integers).
>
> Todd.
>
>
> On Thursday, December 14, 2017, 10:45:17 AM GMT+13, Bill Lorensen <
> bill.lorensen at gmail.com> wrote:
>
>
> I found the problem. The OBJImporter skips any polydata that
>           // If some vertices have tcoords and not others (likewise
> normals)
>           // then we must do something else VTK will complain. (crash
> on render attempt)
>           // Easiest solution is to delete polys that don't have
> complete tcoords (if there
>           // are any tcoords in the dataset) or normals (if there are
> any normals in the dataset).
>
> If does without warning. Only report the skipping  if debug is on.
> This is bad!!!
>
> I'll try to fix the problem in a different way. At the very least I'll
> warn out loud about the skipping.
>
> I've attached a model.obj that removes the tcoords and normals.
>
> Bill
>
>
> On Wed, Dec 13, 2017 at 3:35 PM, Bill Lorensen <bill.lorensen at gmail.com>
> wrote:
> > There must be a bug in the OBJImporter. It reports 4 actors, but only
> > one has polygons. The others report 0 polygons.
> >
> > I'll take a look.
> >
> >
> > On Wed, Dec 13, 2017 at 2:07 PM, Tony Yuan <tonyuanac at gmail.com> wrote:
> >> Hi Sebastien,
> >>
> >> The js loader works fine, but I couldn’t get the same behavior in C++. I
> >> tried to see if the reader has multiple outputs, but
> >> objReader.getNumberOfOutputPorts() returns 1.
> >>
> >> I am interested in getting the mesh as a vtkPolyData, is there a way I
> can
> >> do that with OBJImporter? There seems to be no GetOutput function like
> >> OBJReader.
> >>
> >> Tony
> >>
> >> On Dec 13, 2017, at 12:25 PM, Sebastien Jourdain
> >> <sebastien.jourdain at kitware.com> wrote:
> >>
> >> The file you sent have several materials and I think that the
> vtkOBJReader
> >> just read the first one as it is focusing on the mesh only.
> >>
> >> Your file is correct and I've tried it with vtk.js with success here:
> >> https://kitware.github.io/vtk-js/examples/OBJViewer.html
> >>
> >> But you may have more luck with the importer which could also process
> the
> >> mtl file that should come along. That way all the pieces that compose
> that
> >> object will be loaded.
> >>
> >> Seb
> >>
> >> On Wed, Dec 13, 2017 at 9:40 AM, Tony Yuan <tonyuanac at gmail.com> wrote:
> >>>
> >>> Hi,
> >>>
> >>> I have a problem reading Blender OBJ files using VTK. The vtkOBJReader
> >>> seems to only read part of the mesh. When I render the data being read
> it
> >>> looks like this:
> >>>
> >>>
> >>>
> >>> However, when I import the OBJ file in Meshlab it looks fine. Mac’s
> >>> Preview is also able to open the complete mesh.
> >>>
> >>>
> >>>
> >>> I attached the OBJ file and my code below. I am not very familiar with
> the
> >>> OBJ format and how vtkOBJReader is implemented. If someone could point
> me to
> >>> the problem and possible fixes, that would be great.
> >>>
> >>>
> >>>
> >>> Thanks,
> >>> Tony
> >>>
> >>>
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> >>
> >>
> >>
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> >
> >
> >
> > --
> > Unpaid intern in BillsBasement at noware dot com
>
>
>
> --
> Unpaid intern in BillsBasement at noware dot com
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>
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>
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