Hello everyone,
I love how easy it is to create a mesh of an irregular volume with “Parallel Sculpt”.
However, when I create a mesh with sculpt all edges are smoothed and rounded. See this screenshot with the volume (with sharp edge) and the resulting mesh with rounded edges:
Is there a way to keep the sharp edges of the original geometry?
Best regards and thanks in advance for your help,
Willi
Greetings @Willi!
There is a beta-capability, that is not exposed in the GUI so you’ll need to use a terminal (command prompt on Windows) to access it. The command-line parameter is --capture and it accepts a value that specifies which features to capture. Below is a print-out of the manual for the capture functionality:
Input file command: capture <arg>
Command line options: -c <arg>
Argument Type: integer (0, 1, 2)
Input arguments: off (0)
on (1)
external_surfaces (2)
projections_only (3)
feature_angle_smooth (4)
topology_smooth (5)
Command Description:
This is an experimental option still in development. Nodes at the surfaces
of a default sculpt mesh will not necessarily exactly lie on the geometric surfaces
prescribed by the input STL geometry. While this characteristic can provide
additional flexibility for defeaturing and element quality, there are cases where
a more exact surface representation may be desired. The capture option attempts
to address this by extracting sharp features and/or projecting nodes to the facet
geometry.
Several options are currently being studied as possible solutions. They include
the following:
0 = (off) Capture option is off. No attempt is made at capturing sharp features.
1 = (on) STL geometry is used as basis for feature capture. A user defined
feature angle is used (capture_angle) to first generate groups of facets from the
STL geometry based on capture_angle. Topological curves are defined based
on projections to closest surface facets and edges. With default smoothing option,
the surface nodes will be projected to the closest STL surfaces as a final step
before exporting the exodus mesh. Consider using smooth = to_geometry option.
2 = (exterior_surfaces) Only exterior surfaces are captured. Uses the same
procedure as described in capture = 1, except that interior surfaces (those with
two adjacent volumes), will be ignored in the capture and projections stage.
3 = (projections_only) For this option, additional topology based on feature
angle is not extracted. Only the final projection of surface nodes to the STL
facets is done. Note that this option is useful for organic shapes that do not
have sharp features, or where sharp features should be ignored.
4 = (feature_angle_smooth) This option uses the procedure outlined in
capture = 1, except that the smooth = to_geometry is used by default.
Note that capture = 1 used with smooth = to_geometry should be
identical to this option.
5 = (topology_smooth) Curve topology is defined similar to capture = 1,
except that element face topology is first determined based on closest assigned
facet. Curve topology is then extracted based on adjacent element face associativity.
Surface node projections are only done for nodes that have unambiguous neighbor
associativity. This provides for a tolerant approach to resolving topology that
may result in defeaturing. (i.e. where the STL facet topology may be locally
more complex than can be resolved by the prescribed resolution). This option
also uses the smooth = to_geometry option as default for smoothing. Also
note that capture = 5 it is only currently available for serial execution
(j=1)
Thank you for the fast reply!
I will take a look into this and try if it works for my geometry.
Best regards,
Willi
To help with building your Sculpt command, I would recommend selecting the Create Input File and Do not run Sculpt options in the GUI:
and then open the sculpt_parallel.i file that is generated – and then add the capture command:
$ Input file created: Mon Mar 1 07:54:43 2021
BEGIN SCULPT
nelx = 197
nely = 121
nelz = 96
xmin = -13.274500
ymin = -15.125500
zmin = -23.349500
xmax = 35.975500
ymax = 15.124500
zmax = 0.650500
laplacian_iters = 5
pillow = 1
exodus_file = sculpt_parallel.diatom_result
diatom_file = sculpt_parallel.diatom
capture = 4 <----- ADD THIS LINE (delete this comment)
END SCULPT
Then you’ll simply run sculpt with the following structure:
## Serial Execution
& 'C:\Program Files\Coreform Cubit 2020.2\bin\sculpt.exe' -i .\sculpt_parallel.i
## Parallel Execution
& 'C:\Program Files\Coreform Cubit 2020.2\bin\sculpt.exe' -j <Num Processors> -i .\sculpt_parallel.i
This will output an Exodus file (*.e) that you can load into Cubit.