This code implements the ACM SIGGRAPH 2024 paper: Adaptive grid generation for discretizing implicit complexes. Given one or multiple functions in 3D and desired type of implicit complex defined by these functions (e.g., implicit arrangement, material interface, CSG, or curve network), this algorithm generates an adaptive simplicial (tetrahedral) grid, which can then be used to discretize the implicit complex using this robust method.
Use the following command to build:
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
makeThe program isosurfacing will be generated in the build file.
Currently, all the packages dependencies are available. These are currently in a release process and will be available shortly.
To use the isosurfacing tool, you must provide an initial mesh file and implicit function file as arguments, along with any desired options.
./isosurfacing <mesh> <function> [OPTIONS]mesh : The path to the initial mesh file that will be used for isosurfacing. This file can either be a .msh or .json file.
Examples of mesh files can be found in the data/mesh directory.function : The path to the implicit function file that is used to evaluate the isosurface.-h, --help : Show the help message and exit the program.-t, --threshold : Set the threshold value for the isosurface generation. This is a DOUBLE value that defines the precision level of the isosurfacing.-o, --option : Set the type of the implicit complexes from Implicit Arrangement(IA), Material Interface(MI), or Constructive Solid Geometry(CSG). This is a STRING value that takes input from "IA", "MI", and "CSG". The default type is "IA".--tree : The path to the CSG tree file that defines the set of boolean operations on the functions. Only required if the option is set to be "CSG".-c, --curve_network : Set the switch of extracting only the Curve Network. Notice that Curve Network of all the above implicit complexes are different given the same set of input functions. This is a BOOLEAN type that takes in 1 or 0.-m, --max-elements : Set the maximum number of elements in the mesh after refinement. This is an INT value that limits the size of the generated mesh. If this value is a negative number, the mesh will be refined until the threshold value is reached.-s,--shortest-edge : Set the shortest length of edges in the mesh after refinement. This is a DOUBLE value that defines the shortest edge length.The following is an example of how to use the isosurfacing tool with all available options:
./isosurfacing ../data/mesh/cube6.msh ../data/function_examples/1-sphere.json -t 0.01 -o "IA" -m 10000 -s 0.05In this example, cube6.msh is the initial mesh file, sphere.json is the implicit function file, 0.01 is the threshold value, "IA" is the type of implicit complexes, 10000 is the maximum number of elements, and 0.05 is the shortest edge length.
Examples from the paper can be found in the data folder, where each example contains a mesh file and a function file. If the example is a CSG, then it also includes a CSG tree file. Each figure folder also contains a figure.sh and a figure.bat file containing the exact commandline to produce the examples from the paper.
You can always run ./isosurfacing -h to display the help message which provides usage information and describes all the options available.
The complete set of output files include data files (tet_mesh.msh, active_tets.msh, mesh.json, and function_value.json) and information files (timings.json and stats.json). The first two files can be viewed using Gmsh software showing the entire background grid or only the grid elements containing the surfaces. The last two files are for the later isosurfacing tool.
We have an off-the-shelf algorithm that extracts the isosurfacs robustly from the grid for implicit complexes. First download and build this isosurfacing method following its instructions.
After generating the grid using our method, please use the above isosurfacing tool by replacing its config_file with data/config.json according its usage example:
./impl_arrangement [OPTIONS] config_fileCurrently, this isosurfacing tool supports implicit arrangement, material interface, and CSG. For CSG, please specify the same path to the CSG tree file using the same command.
timing.json: timing of different stages of our pipeline. Details can be found in the paper.
stats.json: statistics of the background grid, e.g., the worst tetrahedral quality (radius ratio).