[GiDlist] varying mesh quality

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Smith, Mark

[GiDlist] varying mesh quality

Post by Smith, Mark »

Hi GiD team
I have been repeatedly meshing a solid with normal tetrahedral elements with a fixed element size and the identical meshing parameters set in the utilities:meshing and get wildly different mesh quality (minimum dihedral angle) results for the mesh.
The results of 12 meshing runs gave me the following results for the minimum dihedral angle (smallest i.e. angle from) all in degrees.
1.35, 5.38, 1.31, 1.01, 3 wrong volumes, 13.7, 8.33, 3 wrong volumes, 6.78, 1 wrong volume, 7.98, 2.18
The largest angle was always the same at 70.5°.
Repeating the test with quadratic tetrahedral elements gave the following results
9.76, 1.31, 3.33, 3.9, gid encountered a problem & needs to close, 5.19, 2.83, 0.887, 1.73, 5.1, 1.36, 3.58
Again the largest angle was always the same at 70.5°.
Is this as expected?

Prior to this series of tests I had assumed when I got the error message "wrong volumes" that there was something wrong with my model or my selection of mesh size but now I know this is not the case. It appears that the meshing routine has an element of randomness and not wholly deterministic otherwise I would get the same mesh each and every time I pressed the mesh button?
If I want the best quality mesh is there any other way other than repeatedly meshing & inspecting the quality until I get one that I'm happy with? as this can be a highly time consuming activity.

GiD version 9.0.4 windowsXP 32bit.

Hoping you can help.
Regards
mark

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[GiDlist] automated response

Post by Eric TONICELLO »

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Thanh Chau Dinh

[GiDlist] automated response

Post by Thanh Chau Dinh »

Dear GiD Team:
Could you please tell me how to download the trial version of Abaqus
Interface module from the GiD homepage?
I tried to use Download-Module but this menu automatically moves to GiD
Plus-Module so that I can not find where the file is.
Thank you in advance.
Thanh
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User avatar
amelendo
Posts: 57
Joined: Tue Sep 16, 2014 2:20 pm

[GiDlist] automated response

Post by amelendo »

El 27/07/2011 9:44, Thanh Chau Dinh escribió:
Dear GiD Team:
Could you please tell me how to download the trial version of Abaqus
Interface module from the GiD homepage?
I tried to use Download-Module but this menu automatically moves to
GiD Plus-Module so that I can not find where the file is.
Thank you in advance.
Thanh


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Dear Thanh,
The Abaqus Interface must be download from GiD-Data-Problem
Type-Internet Retrieve
From this link:
http://www.gidhome.com/gid-plus/modules/interfaces-for-third-party-software/75-abaqus-interface
You can find installation instructions:
http://www.gidhome.com/gid-plus/modules/interfaces-for-third-party-software/213

Regards,
Adrià
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Miguel Baritt

[GiDlist] Surface and Volume from a Cloud Point Data

Post by Miguel Baritt »

Hi all,

I have a point cloud data from 3d scanner. I need to create the surface
defined by that point cloud, and then create the volume enclosed by that
surface. Is this possible to make it in gid? How?

Thanks in advance.

Miguel Baritto


Español (spanish):

Hola,

Tengo una nube de puntos obtenida a partir de un scanner 3d. Necesito crear
la superficie definida por esa nube de puntos, y luego generar el volumen
encerrado por esa superficie. Puede hacerse con gid?

Gracias,

Miguel Baritto
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escolano
Posts: 1918
Joined: Sun Sep 05, 1982 10:51 pm

[GiDlist] Surface and Volume from a Cloud Point Data

Post by escolano »

In general is not possible to do this in an automatic way.

Depending on how the cloud of points is, you could try different approaches.
I recommend you that if it is possible you create by hand (connecting some points) a net of appropiated curves that define the shape, and then create the surfaces by the boundary of this lines.
e.g. you can use
Geometry-Create-NURBS surface-By points
to create some patche that approximate a cloud of points projecting them on a direction. But you must select only groups of 'projectable' points of a relativelly smooth region.

Sometimes scanners include software to create triangles that connect the cloud of points, these triangles could aid you to create smooth surfaces from them
e.g. for simple cases can try
Geometry-Create-Geometry from mesh...
or maybe you can directly work with the triangle mesh creating pseudo-surfaces with
Geometry-Creata-Surface mesh...
that can be used as volume boundary and re-meshed, also for simple cases.

If you send your data, I can have a look to provide you some advice about how to handle it.
(could send directly to escolano at cimne.upc.edu)

Regards
Enrique Escolano
----- Original Message -----
From: Miguel Baritt
To: gidlist at gatxan.cimne.upc.es ; gidlist at listas.cimne.upc.edu
Sent: Monday, August 15, 2011 6:41 PM
Subject: [GiDlist] Surface and Volume from a Cloud Point Data


Hi all,

I have a point cloud data from 3d scanner. I need to create the surface defined by that point cloud, and then create the volume enclosed by that surface. Is this possible to make it in gid? How?

Thanks in advance.

Miguel Baritto


Español (spanish):

Hola,

Tengo una nube de puntos obtenida a partir de un scanner 3d. Necesito crear la superficie definida por esa nube de puntos, y luego generar el volumen encerrado por esa superficie. Puede hacerse con gid?

Gracias,

Miguel Baritto



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