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JIGSAW(GEO) is a set of algorithms designed to generate unstructured grids for computational geophysics. Applications include: large-scale atmospheric simulation and numerical weather prediction, global and coastal ocean-modelling, and ice-sheet dynamics.

JIGSAW(GEO) can be used to produce high-quality staggered Delaunay / Voronoi tessellations for unstructured finite-volume / element type models. Grids can be generated in local two-dimensional domains, and over general spheroidal surfaces. Mesh resolution can be adapted to follow complex user-defined metrics, including: topographic contours, discrete solution profiles or coastal features. These features enable the generation of complex, multi-resolution climate process models, with simulation fidelity enhanced in regions of interest.

JIGSAW(GEO) is a stand-alone mesh generator written in c++, based on the general-purpose meshing package JIGSAW. This toolbox provides a MATLAB / OCTAVE based scripting interface, including file I/O, mesh visualisation and post-processing facilities. The underlying JIGSAW library is a collection of unstructured triangle- and tetrahedron-based meshing algorithms, designed to produce high quality Delaunay-based grids for computational simulation. JIGSAW includes both Delaunay-refinement based algorithms for the construction of new meshes, as well as optimisation driven methods for the improvement of existing grids.

JIGSAW(GEO) is typically able to produce the very high-quality unstructured grids required by contemporary unstructued general circulation models (i.e. MPAS, COMPAS, FESOM, ICON, etc), generating highly optimised, multi-resolution meshes that are locally-orthogonal, mutually-centroidal and self-centred.

JIGSAW(GEO) has been compiled and tested on various 64-bit Linux , Windows and Mac based platforms.

JIGSAW(GEO) is a multi-part library, consisting of a MATLAB / OCTAVE front-end, and a core c++ back-end. All of the heavy-lifting is done in the c++ layer - the interface contains additional scripts for file I/O, visualisation and general data processing:

JIGASW(GEO)::
├── mesh-util -- MATLAB/OCTAVE utilities
└── jigsaw
    ├── src -- JIGSAW src code
    ├── inc -- JIGSAW header files (for libjigsaw)
    ├── bin -- put JIGSAW exe binaries here
    ├── lib -- put JIGSAW lib binaries here
    ├── geo -- geometry definitions and input data
    ├── out -- default folder for JIGSAW output
    └── uni -- unit tests and libjigsaw example programs

The MATLAB / OCTAVE interface is provided for convenience - you don't have to use it, but it's probably the easiest way to get started!

It's also possible to interact with the JIGSAW back-end directly, either through (i) scripting: building text file inputs and calling the JIGSAW executable from the command-line, or (ii) programmatically: using JIGSAW data-structures within your own applications and calling the library via its API.

The first step is to compile the code! The JIGSAW src can be found in ../jigsaw/src/.

JIGSAW is a header-only package - there is only the single main jigsaw.cpp file that simply #include's the rest of the library as headers. The resulting build process should be fairly straight-forward as a result. JIGSAW does not currently dependent on any external packages or libraries.

JIGSAW has been successfully built using various versions of the g++ and llvm compilers. Since the build process is a simple one-liner, there's no make script - instead:

g++ -std=c++11 -pedantic -Wall -s -O3 -flto -D NDEBUG -I libcpp 
-static-libstdc++ jigsaw.cpp -o jigsaw64r

can be used to build a JIGSAW executable, while:

g++ -std=c++11 -pedantic -Wall -O3 -flto -fPIC -D NDEBUG -I libcpp 
-static-libstdc++ jigsaw.cpp -shared -o libjigsaw64r.so

can be used to build a JIGSAW shared library. See the headers in ../jigsaw/inc/ for details on the API. The #define __lib_jigsaw directive in jigsaw.cpp toggles the source between executable and shared-library modes.

JIGSAW has been successfully built using various versions of the msvc compiler. I do not provide a sample msvc project, but the following steps can be used to create one:

* Create a new, empty MSVC project.
* Import the jigsaw.cpp file, this contains the main() entry-point.
* Modify the MSVC project settings to include the "../src/" and "../src/libcpp/" directories.

Once you have built the JIGSAW binaries, place them in the appropriate sub-folders in../jigsaw/bin/ and/or ../jigsaw/lib/ directories, so that they can be found by the MATLAB / OCTAVE interface, and the unit tests in ../jigsaw/uni/. If you wish to support multiple platforms, simply build binaries for each OS and place them in the appropriate directory - the MATLAB / OCATVE interface will do an OS-dependent lookup to call the appropriate binary.

After downloading and building the code, navigate to the root JIGSAW(GEO) directory within your MATLAB / OCTAVE installation to run the set of examples contained in meshdemo.m:

meshdemo(1); % a simple, two-dimensional domain.
meshdemo(2); % a multi-resolution grid for the Australian region.
meshdemo(3); % a uniform resolution spheroidal grid.
meshdemo(4); % a global grid with regional "patch".
meshdemo(5); % a global grid with multi-resolution grid-spacing constraints.

Additionally, the ../jigsaw/example.jig file provides a description of JIGSAW's configuration options, and can be used as a command-line example. A set of unit-tests and libjigsaw example programs are contained in ../jigsaw/uni/. The JIGSAW-API is documented via the header files in ../jigsaw/inc/.

This program may be freely redistributed under the condition that the copyright notices (including this entire header) are not removed, and no compensation is received through use of the software. Private, research, and institutional use is free. You may distribute modified versions of this code UNDER THE CONDITION THAT THIS CODE AND ANY MODIFICATIONS MADE TO IT IN THE SAME FILE REMAIN UNDER COPYRIGHT OF THE ORIGINAL AUTHOR, BOTH SOURCE AND OBJECT CODE ARE MADE FREELY AVAILABLE WITHOUT CHARGE, AND CLEAR NOTICE IS GIVEN OF THE MODIFICATIONS. Distribution of this code as part of a commercial system is permissible ONLY BY DIRECT ARRANGEMENT WITH THE AUTHOR. (If you are not directly supplying this code to a customer, and you are instead telling them how they can obtain it for free, then you are not required to make any arrangement with me.)

DISCLAIMER: Neither I nor: Columbia University, the Massachusetts Institute of Technology, the University of Sydney, nor the National Aeronautics and Space Administration warrant this code in any way whatsoever. This code is provided "as-is" to be used at your own risk.

Information and references regarding the formulation of the underlying JIGSAW mesh-generator can also be found here. Additionally, there are a number of publications that describe the algorithms used in JIGSAW(GEO) in detail. Please cite as appropriate:

[1] - Darren Engwirda: Generalised primal-dual grids for unstructured co-volume schemes, under review, https://arxiv.org/abs/1712.02657, 2017.

[2] - Darren Engwirda: JIGSAW-GEO (1.0): locally orthogonal staggered unstructured grid generation for general circulation modelling on the sphere, Geosci. Model Dev., 10, 2117-2140, https://doi.org/10.5194/gmd-10-2117-2017, 2017.

[3] - Darren Engwirda: Multi-resolution unstructured grid-generation for geophysical applications on the sphere, Research note, Proceedings of the 24th International Meshing Roundtable, https://arxiv.org/abs/1512.00307, 2015.

[4] - Darren Engwirda, Locally-optimal Delaunay-refinement and optimisation-based mesh generation, Ph.D. Thesis, School of Mathematics and Statistics, The University of Sydney, http://hdl.handle.net/2123/13148, 2014.