GiD forum

Hi all,

I have a cloud of points and I want to create a mesh from them. In this
mail list I learned that I have the option of creating a NURBS surface that
approximate smoothly a cloud of irregular points by doing
Geometry-Create-NURBS surface-By points..., and selecting the points.
But when I do that, the boundary of my mesh is a rectangle (as you can see
from the attached picture) and not the boundary of the cloud of point. So
my question is, how can I create a quadrilateral mesh from a cloud of
points in which the boundary's mesh will coincide with the end of my points
(the points' boundary)?
Was it clear enough? Sorry for my english...

Best regards,
Julia
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As you pointed the NURBS surface that approximate a cloud of points is a
rectangular shape (projecting the points in a direction).



If do you have the curves of the contour of your domain, you can create
lateral surface extruding these curves along the projection direction some
distance (using the Utilities-Copy tool) ,

and then calculate the intersection of these surfaces with the squared
surface (Geometry-Edit-Intersection-Surfaces), in order to trim the
terrain with the wanted boundary, and then delete the outer part of the
trimmed surface.



Once do you have the trimmed NURBS surface you want, you can generate the
mesh of unstructured triangles or quadrilaterals.



Regards



Enrique Escolano





De: gidlist-bounces at listas.cimne.upc.edu
[mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de Julia Camargo
Enviado el: lunes, 17 de marzo de 2014 21:16
Para: gidlist at listas.cimne.upc.edu
Asunto: [GiDlist] Meshing a terrain from a cloud of points



Hi all,

I have a cloud of points and I want to create a mesh from them. In this mail
list I learned that I have the option of creating a NURBS surface that
approximate smoothly a cloud of irregular points by doing
Geometry-Create-NURBS surface-By points..., and selecting the points. But
when I do that, the boundary of my mesh is a rectangle (as you can see from
the attached picture) and not the boundary of the cloud of point. So my
question is, how can I create a quadrilateral mesh from a cloud of points in
which the boundary's mesh will coincide with the end of my points (the
points' boundary)?

Was it clear enough? Sorry for my english...

Best regards,
Julia

-------------- next part --------------
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Nice, I think I understood you! I will try to do that. As soon as I have
good news, I'll let you know.
Thank you!


2014-03-17 17:34 GMT-03:00 Enrique Escolano escolano at cimne.upc.edu:

As you pointed the NURBS surface that approximate a cloud of points is a
rectangular shape (projecting the points in a direction).



If do you have the curves of the contour of your domain, you can create
lateral surface extruding these curves along the projection direction some
distance (using the Utilities-Copy tool) ,

and then calculate the intersection of these surfaces with the squared
surface (Geometry-Edit-Intersection-Surfaces), in order to trim the
terrain with the wanted boundary, and then delete the outer part of the
trimmed surface.



Once do you have the trimmed NURBS surface you want, you can generate the
mesh of unstructured triangles or quadrilaterals.



Regards



Enrique Escolano





*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *Julia Camargo
*Enviado el:* lunes, 17 de marzo de 2014 21:16
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* [GiDlist] Meshing a terrain from a cloud of points



Hi all,

I have a cloud of points and I want to create a mesh from them. In this
mail list I learned that I have the option of creating a NURBS surface that
approximate smoothly a cloud of irregular points by doing
Geometry-Create-NURBS surface-By points..., and selecting the points.
But when I do that, the boundary of my mesh is a rectangle (as you can see
from the attached picture) and not the boundary of the cloud of point. So
my question is, how can I create a quadrilateral mesh from a cloud of
points in which the boundary's mesh will coincide with the end of my points
(the points' boundary)?

Was it clear enough? Sorry for my english...

Best regards,
Julia

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist


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Hello.When setting up the .bas file, how can one differentiate among a Quad4, Quad8 or Quad9 element type?Thanks in advance!
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Use the .bas command

*IsQuadratic

It is global for the whole mesh, all elements are quadratic or not.



You can write the element connectivities efficiently without need to know if
it is quadratic or not with *elemsconec :without any argument it write all
its nodes, e.g.



*loop elems

*elemsnum *elemsconec

*end elems





De: gidlist-bounces at listas.cimne.upc.edu
[mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de David R. José
Enviado el: martes, 18 de marzo de 2014 20:55
Para: gidlist at listas.cimne.upc.edu
Asunto: [GiDlist] Quadratic elements



Hello.

When setting up the .bas file, how can one differentiate among a Quad4,
Quad8 or Quad9 element type?

Thanks in advance!

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Hi Enrico,
I managed to do a quadrilateral surface mesh from my cloud of points. Now
my objetive is to extrude this surface and create a volume from that. Then
I want to generate a hexaedra mesh. Well the first part I suceeded. I have
the volume in the shape I need. Do you agree with me that I could mesh that
in a semi-structured way? But I keep receiving the message that *"Volume
can't be semi-structured. They must be prismatic volumes and all boundaries
surfaces but two (the top ones) must be able to be structured."* Can you
guess what my problem is?
Thank you a lot for your help,
Best regards,
Julia


2014-03-17 17:45 GMT-03:00 Julia Camargo juliatcamargo at gmail.com:

Nice, I think I understood you! I will try to do that. As soon as I have
good news, I'll let you know.
Thank you!


2014-03-17 17:34 GMT-03:00 Enrique Escolano escolano at cimne.upc.edu:

As you pointed the NURBS surface that approximate a cloud of points is a
rectangular shape (projecting the points in a direction).



If do you have the curves of the contour of your domain, you can create
lateral surface extruding these curves along the projection direction some
distance (using the Utilities-Copy tool) ,

and then calculate the intersection of these surfaces with the squared
surface (Geometry-Edit-Intersection-Surfaces), in order to trim the
terrain with the wanted boundary, and then delete the outer part of the
trimmed surface.



Once do you have the trimmed NURBS surface you want, you can generate the
mesh of unstructured triangles or quadrilaterals.



Regards



Enrique Escolano





*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *Julia Camargo
*Enviado el:* lunes, 17 de marzo de 2014 21:16
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* [GiDlist] Meshing a terrain from a cloud of points



Hi all,

I have a cloud of points and I want to create a mesh from them. In this
mail list I learned that I have the option of creating a NURBS surface that
approximate smoothly a cloud of irregular points by doing
Geometry-Create-NURBS surface-By points..., and selecting the points.
But when I do that, the boundary of my mesh is a rectangle (as you can see
from the attached picture) and not the boundary of the cloud of point. So
my question is, how can I create a quadrilateral mesh from a cloud of
points in which the boundary's mesh will coincide with the end of my points
(the points' boundary)?

Was it clear enough? Sorry for my english...

Best regards,
Julia

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist



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If you have created the volume with the copy tool with extrusion, then it
seems that this volume must be valid to be meshed semi-structured.

Are you sure that all lateral surfaces have 4 sides?



Send me a zip with your model to have a look (directly to
escolano at cimne.upc.edu instead of the gidlist)



Enrique



De: gidlist-bounces at listas.cimne.upc.edu
[mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de Julia Camargo
Enviado el: miércoles, 19 de marzo de 2014 21:15
Para: gidlist at listas.cimne.upc.edu
Asunto: Re: [GiDlist] Meshing a terrain from a cloud of points



Hi Enrico,

I managed to do a quadrilateral surface mesh from my cloud of points. Now my
objetive is to extrude this surface and create a volume from that. Then I
want to generate a hexaedra mesh. Well the first part I suceeded. I have the
volume in the shape I need. Do you agree with me that I could mesh that in a
semi-structured way? But I keep receiving the message that "Volume can't be
semi-structured. They must be prismatic volumes and all boundaries surfaces
but two (the top ones) must be able to be structured." Can you guess what my
problem is?

Thank you a lot for your help,

Best regards,
Julia



2014-03-17 17:45 GMT-03:00 Julia Camargo juliatcamargo at gmail.com:

Nice, I think I understood you! I will try to do that. As soon as I have
good news, I'll let you know.

Thank you!



2014-03-17 17:34 GMT-03:00 Enrique Escolano escolano at cimne.upc.edu:

As you pointed the NURBS surface that approximate a cloud of points is a
rectangular shape (projecting the points in a direction).



If do you have the curves of the contour of your domain, you can create
lateral surface extruding these curves along the projection direction some
distance (using the Utilities-Copy tool) ,

and then calculate the intersection of these surfaces with the squared
surface (Geometry-Edit-Intersection-Surfaces), in order to trim the
terrain with the wanted boundary, and then delete the outer part of the
trimmed surface.



Once do you have the trimmed NURBS surface you want, you can generate the
mesh of unstructured triangles or quadrilaterals.



Regards



Enrique Escolano





De: gidlist-bounces at listas.cimne.upc.edu
[mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de Julia Camargo
Enviado el: lunes, 17 de marzo de 2014 21:16
Para: gidlist at listas.cimne.upc.edu
Asunto: [GiDlist] Meshing a terrain from a cloud of points



Hi all,

I have a cloud of points and I want to create a mesh from them. In this mail
list I learned that I have the option of creating a NURBS surface that
approximate smoothly a cloud of irregular points by doing
Geometry-Create-NURBS surface-By points..., and selecting the points. But
when I do that, the boundary of my mesh is a rectangle (as you can see from
the attached picture) and not the boundary of the cloud of point. So my
question is, how can I create a quadrilateral mesh from a cloud of points in
which the boundary's mesh will coincide with the end of my points (the
points' boundary)?

Was it clear enough? Sorry for my english...

Best regards,
Julia



_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist





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