[vtkusers] vtkusers Digest, Vol 145, Issue 16

Richard Frank rickfrank at me.com
Mon May 16 13:38:21 EDT 2016


Sorry for the blank reply previous.

The Tutorial is great but I don't see an example of the case I'm talking about.

That is, returning a pointer to the caller in such a way that the caller doesn't  have to think about whether they need to explicitly delete.

so, given a function  or method with a signature already returning a bool, and other code already dependent on that return type, I want to return the result of reading a file, for instance:

bool ReadAnImageFile(vtkSmartPointer<vtkImageData> & theImageRead)
{
   vtkSmartPointer<vtkImageFileReader> reader =  vtkSmartPointer<vtkImageFileReader>::New9);

reader->SetFileName("Something.png");
reader->Update();

vtkImageData * image =  reader->GetOutput();  How to get image into theImageRead?

// This seems to work

theImageRead->DeepCopy(image);

// but if it's really doing a deep copy and I have a large 3D .mha file or something
// it will be slow.....is there a better way?
}


Thanks

Rick

On May 16, 2016, at 12:00 PM, vtkusers-request at vtk.org wrote:

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Today's Topics:

1. why does the generated 3D model have borken part? (Liu_tj)
2. Re: SmartPointer reference? (Dan Lipsa)
3. Re: vtkBooleanOperationPolyDataFilter creates  non-manifold
edges (Andras Lasso)


----------------------------------------------------------------------

Message: 1
Date: Mon, 16 May 2016 21:11:33 +0800 (CST)
From: Liu_tj <tjlp at netease.com>
To: vtkusers <vtkusers at vtk.org>
Subject: [vtkusers] why does the generated 3D model have borken part?
Message-ID: <7543d5b6.11.154b9b16f2f.Coremail.tjlp at netease.com>
Content-Type: text/plain; charset="utf-8"

Hi,

I used vtkMarchingCubes, vtkDecimatePro and vtkSmoothPolyDataFilter to generate 3D model for DICOM image. When it is firstly generated, the 3D model is fine (See the attached First.jpg). However, when I store it to STL file and use STLReader to read the STL file and display in vtkRenderWindow, it shows broken part (See loading.jpg). Why?

Thanks
Liu Peng

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Message: 2
Date: Mon, 16 May 2016 10:18:30 -0400
From: Dan Lipsa <dan.lipsa at kitware.com>
To: Richard Frank <rickfrank at me.com>
Cc: VTK Users <vtkusers at vtk.org>
Subject: Re: [vtkusers] SmartPointer reference?
Message-ID:
 <CADwGrVq4_tna0Oph5Tqn+m=6Uk4GTn8GJuGBvdfZ8XudbjcsBA at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Does this help?
http://www.vtk.org/Wiki/VTK/Tutorials/SmartPointers

What exactly is the problem you are seeing?
Dan


On Fri, May 13, 2016 at 7:22 PM, Richard Frank <rickfrank at me.com> wrote:


Hi,

Is it possible to return a smart pointer by reference?

I'd like to return an image as a parameter, rather than a return type but
nothing seems to be happy.

for instance

bool SomeFunction(vtkSmartPointer<vtkImageData> & outImage)
{
vtkSmartPointer<vtkImageReader> r =
vtkSmartPointer<vtkImageReader>::New();
r->SetFileName("Path");
r->Update();
// What next?

return true;
}

I though Take was a possible choice

outImage = vtkSmartPointer<vtkImageData>::Take(r->GetOutput());

but no happiness there.

Any solution?

Thanks

Rick



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Message: 3
Date: Mon, 16 May 2016 15:14:15 +0000
From: Andras Lasso <lasso at queensu.ca>
To: normanius <juch at zhaw.ch>, "vtkusers at vtk.org" <vtkusers at vtk.org>
Subject: Re: [vtkusers] vtkBooleanOperationPolyDataFilter creates
   non-manifold        edges
Message-ID:
       <DM2PR07MB350120A5448638CA86B2746D8770 at DM2PR07MB350.namprd07.prod.outlook.com>
       
Content-Type: text/plain; charset="us-ascii"

but it cannot be that one has to do that extra cleanup step after every such basic operation, right?!

Performing Boolean operation on meshes may sound easy but is an extremely difficult problem. It would be nice if VTK had a solution that worked reliably, so it's great that you submit reports on specific problems you find.

However, I'm not sure if there is anybody who could work on fixing these issues in the near future. So, if you cannot fix them yourself then most likely your best bet is to work around the problem by converting all meshes to images, combining them, and regenerating a mesh.

Andras

-----Original Message-----
From: vtkusers [mailto:vtkusers-bounces at vtk.org] On Behalf Of normanius
Sent: May 15, 2016 4:54 AM
To: vtkusers at vtk.org
Subject: [vtkusers] vtkBooleanOperationPolyDataFilter creates non-manifold edges

Hi all

This is an issue that has been raised already. But I wanted to ask whether there is a workaround or whether it actually is a bug that has been properly reported.

Find attached sample code which reproduces the problem: If I union two overlapping, watertight objects A and B, the resulting object C very likely won't be watertight (it shows border edges and non-manifold edges).

The sample code in essence does this:
- create cylinder A as a vtk.vtkCylinderSource
- create sphere B as a vtk.vtkSphereSource
- extract triangles from A and B
- create union C with vtk.vtkBooleanOperationPolyDataFilter() with
SetOperationToUnion()

The problem occurs also, if I use other objects than cylinders or spheres.
The problem occurs also, if I "clean/condition" the surfaces of A and B before calculating the union. (I tried vtkCleanPolyData(),
vtkFillHolesFilter() and addition of small noise on the vertices, which sometimes helps to regularise operations on objects)

In the following two screenshots. The first one indicates the two objects to union. The second one shows the result, with the non-manifold and border edges.

<http://vtk.1045678.n5.nabble.com/file/n5738088/input.png>
<http://vtk.1045678.n5.nabble.com/file/n5738088/result.png> 

Because I often make use of vtkBooleanOperationPolyDataFilter, the problem is really annoying for me. That's why I thought to seek help in the community. Any ideas of how to handle this?
Cleaning the surface (set flag cleanOutputSurface=True in my code) does improve the situation in some cases - but it cannot be that one has to do that extra cleanup step after every such basic operation, right?!

By the way: this problem has been reported already: see here <http://vtk.1045678.n5.nabble.com/Non-manifold-triangles-after-running-vtkBooleanOperationPolydataFilter-td5713964.html>
and here
<http://vtk.1045678.n5.nabble.com/Broken-surfaces-for-vtkBooleanOperationPolyDataFilter-Bug-td5735413.html>
reproduced_problem.py
<http://vtk.1045678.n5.nabble.com/file/n5738088/reproduced_problem.py> .

Thanks for any inputs from your side.



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