GiD forum

Hi GiD team,
I'm using version 7.5.8b and I have three minor problems:

1 If I change the problemtype the materials submenu and
some other under "Data" tend to disappear. Note that in the
"Right Buttons" toolbar all the "Data" submenus keep being
there.
2 Drawing the materials with colours changes the background
colour.
3 If I use "Create Object" the snapping is not working,
whereas with lines and points everything is fine. (It seems
the grid button at the right bottom has no ToolTip assigned).

I hope these info can help you improving GiD.

Best regards
Andrea

Hi,

I have an arbitrary surface which has been triangulated outside GID and
converted into a .dxf file to be read into GID. I have the following
questions:

(1) Once the triangulated surface has been read into GID, is there a way to
manipulate it
so as to come up with a smooth surface using nurbs?

(2) Let's say I generate 2 separate volumes from 2 different triangulated
surfaces. I experience problems when trying to subtract one volume from the
other one. I receive an error message saying 'Not Close Volume'.
Can you help me? I am including a simpler example of my problem
which involves the subraction of 2 cylinders generated from triangulated
surfaces.

(3) I am working with large meshes and find GID slow on a PC
(Pentium M Processor 725 (1.60 GHz/400MHz FSB),512 MB Ram).
Do you think that the Linux/Unix version would run
much faster on similar computer configuration, or is it that my PC is simply
slow and I need to upgrade both CPU speed and RAM)

Thanks.

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Dear sir,
About your questions
(1) Once the triangulated surface has been read into GID, is there a way to manipulate it so as to come up with a smooth surface using nurbs?
Dxf is a very bad graphics exchange format, it don't support NURBS surfaces, then smoot surfaces are translated as a collection of triangles, and it's not possible to recover the original smooth shape. For a simple geometry, like yout two cylinders, it's better to reconstruct them in GiD (by revolution, etc), using the imported geometry only to get some dimensions.

Check if your external CAD can export in other better formats, like IGES, Parasolid, ACIS or VDA

(2) Let's say I generate 2 separate volumes from 2 different triangulated surfaces. I experience problems when trying to subtract one volume from the other one. I receive an error message saying 'Not Close Volume'. Can you help me? I am including a simpler example of my problem which involves the subraction of 2 cylinders generated from triangulated surfaces.

Boolean volume operations currently are slow and unstables in GiD.
They are slow because it's necessary to calculate all the intersections between lines-surface, and surfaces-surfaces. It works better with few smooth surfaces instead a lot of small triangles. After calculate intersections, and split entities, sometimes it's not possible to close a volume, and it's necessary manually solve some problem (some failed intersection, etc). This features must be enhanced for future GiD versions.

3) I am working with large meshes and find GID slow on a PC (Pentium M Processor 725 (1.60 GHz/400MHz FSB),512 MB Ram).
Do you think that the Linux/Unix version would run much faster on similar computer configuration, or is it that my PC is simply slow and I need to upgrade both CPU speed and RAM)

The Linux/Unix versions run at similar speed that Windows versions.

Best regards

Enrique Escolano

----- Original Message -----
From: "ya ya" e_oung at hotmail.com
To: gidlist at gatxan.cimne.upc.es
Sent: Saturday, August 06, 2005 12:28 AM
Subject: [GiDlist] Creating a 3D Geometry from triangulated arbitrary surfaces


Hi,

I have an arbitrary surface which has been triangulated outside GID and
converted into a .dxf file to be read into GID. I have the following
questions:

(1) Once the triangulated surface has been read into GID, is there a way to
manipulate it
so as to come up with a smooth surface using nurbs?

(2) Let's say I generate 2 separate volumes from 2 different triangulated
surfaces. I experience problems when trying to subtract one volume from the
other one. I receive an error message saying 'Not Close Volume'.
Can you help me? I am including a simpler example of my problem
which involves the subraction of 2 cylinders generated from triangulated
surfaces.

(3) I am working with large meshes and find GID slow on a PC
(Pentium M Processor 725 (1.60 GHz/400MHz FSB),512 MB Ram).
Do you think that the Linux/Unix version would run
much faster on similar computer configuration, or is it that my PC is simply
slow and I need to upgrade both CPU speed and RAM)

Thanks.

_________________________________________________________________
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Dear Enrique,

Thank-you very much for your quick reply!

1) Once the triangulated surface has been read into GID, is there a way =
to manipulate it so as to come up with a smooth surface using nurbs?
Dxf is a very bad graphics exchange format, it don't support NURBS =
surfaces, then smoot surfaces are translated as a collection of =
triangles, and it's not possible to recover the original smooth shape. =
For a simple geometry, like yout two cylinders, it's better to =
reconstruct them in GiD (by revolution, etc), using the imported =
geometry only to get some dimensions.

Check if your external CAD can export in other better formats, like =
IGES, Parasolid, ACIS or VDA

Unfortunately, the cylinder was a simple fictituous example that I chose in
order to demonstrate to you my problem. Actually, I am dealing with a 3D
arbitrary shaped solid (prostate organ) that I have reconstructed from a
series of ultrasound images defining the outline of the prostate
(cross-sections)in an axial direction. The end result is a triangulated
surface. Right now, when I read it into GID, it takes every single triangle
as a surface and we end up using a large number of triangles (about 10,000),
hence problems with volume subtraction operations and slowness in processing
time. I understand that for Boolean volume substractions, it is better to
have few surfaces, and SMOOTH ones for the algorithm to work well and
'fast'.

You mentioned about getting the data into IGES, Parasolid, ACIS or VDA
format, but the software that I use to construct the triangulated surface
does not support these formats as export format. So, how do I convert my
triangulated surface into a smooth (nurbed) surface that can be read into
GID as one single surface?

Thank-you!!

Bahong

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I don't know any program capable to automatically convert this
triangulations to several smooth surfaces.
I tried some specialized reverse engineering programs, like Delcam CopyCAD,
or Cadmus fashion,
but they can't automatically do this work. (in other hand, I'm not an expert
using this related programs)

Maybe you can send me some real sample (can send directly to
escolano at cimne.upc.es) , in order to enhance
GiD for this type of models.

Regards
Enrique Escolano

----- Original Message -----
From: "ya ya" e_oung at hotmail.com
To: gidlist at gatxan.cimne.upc.es
Cc: wan at ucalgary.ca
Sent: Monday, August 08, 2005 11:53 PM
Subject: [GiDlist] Creating a 3D Geometry from triangulated arbitrary


Dear Enrique,

Thank-you very much for your quick reply!

1) Once the triangulated surface has been read into GID, is there a way =
to manipulate it so as to come up with a smooth surface using nurbs?
Dxf is a very bad graphics exchange format, it don't support NURBS =
surfaces, then smoot surfaces are translated as a collection of =
triangles, and it's not possible to recover the original smooth shape. =
For a simple geometry, like yout two cylinders, it's better to =
reconstruct them in GiD (by revolution, etc), using the imported =
geometry only to get some dimensions.

Check if your external CAD can export in other better formats, like =
IGES, Parasolid, ACIS or VDA

Unfortunately, the cylinder was a simple fictituous example that I chose
in
order to demonstrate to you my problem. Actually, I am dealing with a 3D
arbitrary shaped solid (prostate organ) that I have reconstructed from a
series of ultrasound images defining the outline of the prostate
(cross-sections)in an axial direction. The end result is a triangulated
surface. Right now, when I read it into GID, it takes every single
triangle
as a surface and we end up using a large number of triangles (about
10,000),
hence problems with volume subtraction operations and slowness in
processing
time. I understand that for Boolean volume substractions, it is better to
have few surfaces, and SMOOTH ones for the algorithm to work well and
'fast'.

You mentioned about getting the data into IGES, Parasolid, ACIS or VDA
format, but the software that I use to construct the triangulated surface
does not support these formats as export format. So, how do I convert my
triangulated surface into a smooth (nurbed) surface that can be read into
GID as one single surface?

Thank-you!!

Bahong

_________________________________________________________________
Take advantage of powerful junk e-mail filters built on patented
Microsoft®
SmartScreen Technology.

http://join.msn.com/?pgmarket=en-ca&page=byoa/prem&xAPID=1994&DI=1034&SU=http://hotmail.com/enca&HL=Market_MSNIS_Taglines
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