[Gmsh] Question about Gmsh

[David Colignon]

On 08/11/12 15:04, youngjun at mail.ustc.edu.cn wrote:

> Hi, David,
>
> Thank you for the advice.
>
> The method did work for plane surface, but when the model contains topography, problem comes again. I have to define the curved surface first with GPS data, and then embed the detecting points in the surface. If I still use the command Point | Line { expression-list } In Surface { expression };, it doesn't create a surface with topography.
>
> So the problem is the same as mentioned in my last email: If I have a large number of control points(like GPS data), is there a simple way to create a surface with topography using these points?

Hi,

do you know about the "Triangulate" plug-in ?

Plugin(Triangulate) triangulates the points in the view `View', assuming that all the points belong to a surface that 
can be projected one-to-one onto a plane.
If `View' < 0, the plugin is run on the current view.
Plugin(Triangulate) creates one new view.

and the corresponding "Tetrahedralize" plug-in ?

Plugin(Tetrahedralize) tetrahedralizes the points in the view `View'.
If `View' < 0, the plugin is run on the current view.
Plugin(Tetrahedralize) creates one new view.

>
> By the way, is there a command or combined technique to embed points in a volume like the one for surface?

No, it is much more difficult to implement in the 3D meshing algorithms than in the 2D's

Regards,

Dave


>
> Best Regards,
>
> Jun Yang
>
>
>
>> -----Original E-mail-----
>> From: "David Colignon" <David.Colignon at ulg.ac.be>
>> Sent Time: 2012-11-8 17:40:25
>> To: youngjun at mail.ustc.edu.cn
>> Cc: gmsh at geuz.org
>> Subject: Re: [Gmsh] Question about Gmsh
>>
>> Hi,
>>
>> did you see or try this:
>>
>> https://geuz.org/gmsh/doc/texinfo/gmsh.html#Miscellaneous-mesh-commands
>>
>> Point | Line { expression-list } In Surface { expression };
>>
>>       Embed the point(s) or line(s) in the given surface. The surface mesh will conform to the mesh of the point(s) or
>> lines(s). Note that embedded lines only work with the MeshAdapt 2-D algorithm.
>>
>>
>> Regards,
>>
>> Dave
>>
>> --
>> David Colignon, Ph.D.
>> Collaborateur Logistique du F.R.S.-FNRS
>> CÉCI - Consortium des Équipements de Calcul Intensif
>> ACE - Applied & Computational Electromagnetics
>> Université de Liège
>> Sart-Tilman B28
>> 10, Grande Traverse
>> 4000 Liège - BELGIQUE
>> Tél: +32 (0)4 366 37 32
>> WWW:    http://www.ceci-hpc.be/
>> Agenda: http://www.google.com/calendar/embed?src=david.colignon%40gmail.com
>>
>> On 08/11/12 05:56, youngjun at mail.ustc.edu.cn wrote:
>>> Dear Professor Christophe Geuzaine and Professor Jean-François Remacle,
>>>
>>> I'm a graduate student from University of Science and Technology of China. My major is geophysics and I am now using Gmsh to build models for modeling geoeletric field.
>>>
>>> These models are quite simple. The structure of the model is a cuboid space with some simple bodies whose properties differ from the cuboid space(We call them anomalies) inside it. Then when I try to specify large amount of points that regularly spread on the surface of the model for measuring the eletric potential, it seems that it's not going to be an easy task. I have to define all these points, then create line segments between every two adjacent points, followed by forming line loops to define plane surfaces, and finally put them into a part of the volume in order to execute the 3D mesh. If I don't do it in this way, the produced grid will have nothing to do with these deteting points. However, I need to make sure that these points on the surface are nodes of the elements.
>>>
>>> So is there an easy technique to accomplish this operation? More generally, is there an elementary classification for stand-alone control points which is going to be the nodes of the elements when execute the mesh operation, like the ones I described above? I'm not sure if I miss some important information in the Gmsh Reference Manual, but till now I can't find a simple way.
>>>
>>> The attachment is the .geo file that describes the model I want to build. Only the points, and lines are defined in the file. If these elementaries have to be defined manually, thousands of operations are needed.
>>>
>>> The Gmsh with GUI is quite easy to operate. Thanks for offering us this excellent software!
>>>
>>> Best Regards,
>>> Jun Yang
>>> University of Scinece and Technology of China
>>> Heifei,China
>>> Email: youngjun at mail.ustc.edu.cn
>>>
>>>
>>>
>>> _______________________________________________
>>> gmsh mailing list
>>> gmsh at geuz.org
>>> http://www.geuz.org/mailman/listinfo/gmsh
>>>
>>
>