[vtkusers] How to get the facet normals from stl file

[冒牌天使]

But the stl file contains the normals information, why do I compute the normals again with the vtkPolyDataNormal? Actually I have tried it. The normals geted from the vtkPolyDataNormal is not eaqual to the normals in the file. 
 
 
------------------ Original ------------------
From: "Adriano Gagliardi"; 
Date: 2011年6月17日(星期五) 晚上9:29
To: "'David Doria'"; "'Samu'"; 
Cc: "vtkusers"; 
Subject: RE: [vtkusers] How to get the facet normals from stl file

 

You could always generate the normals from your vtkPolyData input using
vtkPolyDataNormals?


===================================

Adriano Gagliardi MEng PhD
Business Sector Leader
Computational Aerodynamics
Aircraft Research Association Ltd.
Manton Lane
Bedford

Tel: 01234 32 4644
E-mail: agagliardi at ara.co.uk
Url: www.ara.co.uk 
-----Original Message-----
From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf
Of David Doria
Sent: 17 June 2011 14:18
To: Samu
Cc: vtkusers at vtk.org
Subject: Re: [vtkusers] How to get the facet normals from stl file

On Fri, Jun 17, 2011 at 9:06 AM, Samu <gaoxuanhui at foxmail.com> wrote:
> Hi all:
>     I have met a problem about reading the normals information from 
> stl file. I search the mail list and find some people had met the same 
> problem as I do, but the problem was left unsolved. Could anyone give 
> any suggestions?
> Here is the copy of the mail list:
> Hi everyone:
>   Now I can get three points coodinates of the same one triangle facet 
> by the help of Vladimir Lazunin. But I have another question that I 
> cannot solve by myself. In stl file there is normal information of a 
> triangle facet. I want to
>
> get normal information too. I searched the book of vtk user's guide 
> and web,but I
>
> didnot find interface to get normal information of stl file in vtk. 
> Could someone give any suggestions?

You should not think of it as getting normals from an STL file. You should
think about it as reading an STL file into a vtkPolyData, and then getting
normals from a vtkPolyData. If the normals aren't in the vtkPolyData, then
the STL reader is incomplete.

David
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