Tarantula 2.0
A completely new piece of software is behind the release tarantula 2.0. This results in:
-> smoother surfaces,
-> better mesh quality,
-> simpler parameter control,
-> faster meshing time.
The new version is (like the previous) controlled via a configuration file. This file can be now read in standard text format, or in .slk (coming from e.g. openOffice). A sample file looks like:
of course this does the same as in text format:
MESHFILENAME mesh.spm.gz
VOXFILENAME i_wedge.vox.gz
FLIP_VOXELS
ISO_REFINEMENT_LEVEL .5 3
#INTERVAL_REFINEMENT_LEVEL .5 1.5 4
BASEH 8
NOSHRINK_ITERATIONS 3
CUTTING_VALUE .5
#SKIPSMOOTHING
#TAGGING
END
In the following a short description of the parameters:
MESHFILENAME
defines the output-filename
VOXFILENAME
defines the input-filename (voxeldataset)
FLIP_VOXELS
Within the voxeldataset there comes a series of 0 and 1 (non-zeros). This parameter changes non-zeros to zeros and vize versa.
ISO_REFINEMENT_LEVEL param1 param2
Does a local refinement (param2-levels) on the isosurface param1. This means only the surface is refinened.
INTERVAL_REFINEMENT_LEVEL param1 param2 param3
Does a local refinement (param3-levels) on the volume enclosed between the isosurfaces of param1
and param2. This means a volume is refined.
BASEH param1
param1 is used as maximal cellwith. Since the lenght of a voxel is defined within tarantula2.0 as 1-1-1, use a power of 2 for this parameter (2,4,8,16).
NOSHRINK_ITERATIONS param1
Defines the number of smoothing-steps on the voxeldataset. The more smoothing-iterations, the smoother the surface of the resulting mesh but less details. The less smoothing-iterations, the more details, but not that smooth surfaces. A useful range for this parameter is 1-5.
CUTTING_VALUE param1
Defines the isosurface used for mesh generation. A valid range for this parameter is 0.2 to 0.8.
SKIPSMOOTHING
If activated, the generated mesh will not be smoothed and has negative cells (so cannot be used for simulation), but will be much faster. This can be useful for „premeshing“, and checking meshing parameters, or it only the surface will be used lateron.
TAGGING
If not only 0s and 1s are present, all not-zeros are treated as 1s, but the different „tags“ are mapped and available within the mesh as different materials. Still the isosurface can only be done between 0.2 and 0.8.
Remarks:
Tarantula2.0 can only run on voxel-data.
The „default“ setup is BASEH 8 and XXX_REFINENEMT_LEVEL 3 for a coarse (but full detailed) mesh, and BASEH 8 XXX_REFINENEMT_LEVEL 4 for a fine mesh. Leaving these parameter-sets is not recommended.
The values for refinement should be related to the cutting-value. Interval-refining e.g of the interval [0.7 1.1] and a cutting value 0.5 makes no sense (and is therefore not recommended).
For a new meshing job please use a configuration file of an „old“ example, or the configuration file of the tarantula2.0 example.
Check the mesh if is has the correct orientation (or if it is „mirrored“). In the case the mesh is „wrong“, you have to mirror the voxel-dataset (planed to be done within tarantula in the future).
In case tarantula works not as expected, please submit the problem with configuration-file and voxelfile, otherwise the problem cannot be checked.
Freitag, 14. März 2008