[vtkusers] Writing point cloud to .vtk using MATLAB

[rakesh patil]

Dear Haluk,

As far as my knowledge is concerned, these scalars may be either depth
values, temperature, pressure etc defined at those point locations. That's
why it is called POINT_DATA. It can be also used to specify colors for
individual cells in which case, scalars will be assigned to CELL_DATA
instead of POINT_DATA.

Please see this example:

http://www.vtk.org/Wiki/VTK/Examples/Cxx/VTKConcepts/Scalars

Seniors correct me if I am wrong.

Thanks

Regards
Rakesh Patil

On Wed, Sep 14, 2011 at 10:29 PM, Haluk Noyan Tokgozoglu
<htokgoz1 at jhu.edu>wrote:

> Hi,
>
> What are those scalar values supposed to denote?
>
> Haluk Noyan Tokgozoglu
>
> Johns Hopkins University
> Computer Science PhD Student
> Computational Interaction and Robotics Library
> Secretary of the GRO
> Treasurer of UPE
>
>
>
> On Wed, Sep 14, 2011 at 12:21, rakesh patil <prakeshofficial at gmail.com>wrote:
>
>> Hi,
>>
>> As mentioned in the pdf file
>>
>>
>> http://www.vtk.org/VTK/img/file-formats.pdf
>>
>> There must be some scalar values for the POINT_DATA. Check for the example
>> on page number 8 in that file. Your code only writes the x,y,z points in the
>> file. Scalar values should follow after POINT_DATA.
>>
>> Hope that helps.
>>
>> Regards
>> Rakesh Patil
>>
>> On Wed, Sep 14, 2011 at 9:08 PM, Haluk Noyan Tokgozoglu <htokgoz1 at jhu.edu
>> > wrote:
>>
>>> Hi,
>>>
>>> I have point cloud data in the form of 3 vectors, x y z which are n-by-1
>>> and contain the 3 coordinates of the points. I am trying to swiftly generate
>>> a .vtk file in MATLAB so I can view it in Paraview, but I am having trouble
>>> understanding the documentation at
>>> http://www.vtk.org/VTK/img/file-formats.pdf
>>>
>>> I have written some code, where I write the points as an unstructred
>>> grid, but paraview doesn't show anything when I try to view the file.
>>>
>>> Here's my code:
>>>
>>> function [] = write_vtk(x,y,z)
>>>
>>>     n=size(x);
>>>     delete('data.vtk');
>>>     fid=fopen('data.vtk','w');
>>>     fprintf(fid,'# vtk DataFile Version 2.0\n');
>>>     fprintf(fid,'blah\n');
>>>     fprintf(fid,'ASCII\n');
>>>     fprintf(fid,'DATASET UNSTRUCTURED_GRID\n');
>>>     fprintf(fid,'POINTS %d float\n',n);
>>>     for i=1:n
>>>         fprintf(fid,'%f %f %f\n',x(i),y(i),z(i));
>>>     end
>>>     fprintf(fid,'POINT_DATA %d\n',n);
>>>     fclose(fid);
>>>
>>>
>>> end
>>>
>>> What am I doing wrong?
>>>
>>>
>>> Haluk Noyan Tokgozoglu
>>>
>>> Johns Hopkins University
>>> Computer Science PhD Student
>>> Computational Interaction and Robotics Library
>>> Secretary of the GRO
>>> Treasurer of UPE
>>>
>>>
>>>
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