[Paraview] Suggestion for STL import

[Utkarsh Ayachit]

Eugene,

BTW, the reader does support not merging points. I'll check if ParaView
exposes that option, if not, it should. That'll speed this up too.

Utkarsh

On Tue, Jul 5, 2016 at 12:04 PM, Utkarsh Ayachit <
utkarsh.ayachit at kitware.com> wrote:

> Eugene,
>
> I am pretty sure the community will be interested in this! While I'll need
> to look into the reader to understand, to get things going, do you have a
> sample dataset to demonstrate the issue?
>
> Utkarsh
>
> On Tue, Jul 5, 2016 at 10:28 AM, Eugene de Villiers <
> e.devilliers at engys.com> wrote:
>
>> Hi,
>>
>>
>>
>> When importing STL format geometry or similar, where connectivity
>> information is not implicit in the data structure, it appears that the
>> connectivity is reconstructed via an  octree search. This is very
>> inefficient when surfaces with large differences in edge length are
>> imported – we have had a recent case where an STL took 45mins to load. If
>> the same input geometry is converted to OBJ format via an external tool,
>> the load time reduces to minutes.
>>
>>
>>
>> A generally more efficient method is to calculate the distance of each
>> point from a location outside the point cloud bounding box and then to
>> bubble-sort the resulting list. Unless you are dealing with a pathological
>> case your local search neighbourhood of identical distance points will be
>> small and the algorithm very fast. More complex, multi-origin algorithms
>> are also possible to counter pathological instances.
>>
>>
>>
>> I can provide more details and sample code if you are interested.
>>
>>
>>
>> Best regards,
>>
>>
>>
>> *Eugene de Villiers*
>>
>> *Managing Director*
>>
>> e.devilliers at engys.com
>>
>> Mob: +44 (0) 77 89748490
>>
>> Tel: +44 (0)20 32393041 (ext. 102)
>>
>> Fax: +44 (0)20 33573123
>>
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