CGAL 5.3 offers the following improvements and new functionality over CGAL 5.2:
Changelog
General changes

The support for the compiled version of CGAL is dropped. Only the headeronly version is supported.

On Windows, the type used for
Exact_rational
, inEpick
and indirectly (throughLazy_exact_nt
)Epeck
may now beboost::multiprecision::mpq_rational
, as has been the case on other platforms for several releases. This depends on various options and is added to a list that includesmpq_class
,CGAL::Gmpq
,leda_rational
andCGAL::Quotient<CGAL::MP_Float>
.
Quadtrees, Octrees, and Orthtrees (new package)
 This package implements a tree data structure in which each node encloses a hypercubic section of space and each nonleave node has hypercubic children whose edge lengths are half its edge length. Such a data structure is known as a quadtree in 2D, an octree in 3D, and is generalized as an “orthtree” in higher dimensions.
Triangulations on the Sphere (new package)
 This package enables the construction and manipulation of Delaunay triangulations on the 2sphere. Triangulations are built incrementally and can be modified by insertion or removal of vertices. Point location querying and primitives to build the dual Voronoi diagram are provided.
File Input / Output
 Point set, polygon soup, and polygon mesh file I/O functions have been harmonized and documented:
 Point set I/O functions can be found in the packages Point_set_processing_3, and Point_set_3.
 Polygon mesh I/O functions can be found in the package BGL.
 Polygon soup I/O can be found in the package Stream_support.
A comprehensive list of the supported file formats is available in the Stream_support package here; inversely, the following page can be used to find out which CGAL data structures can be used given a specific file format.
Requirements
 The CMake minimal version is now
3.14
.  The GNU compiler g++ versions 6 and 7 are no longer tested. Only version 8.3 or later are supported
2D and 3D Linear Geometry Kernel
 Added
is_translation()
,is_scaling()
,is_reflection()
, andis_rotation()
to the classesAff_transformation_2
andAff_transformation_3
, which enable determining if the transformations use a specialized representation internally.
2D Regularized Boolean SetOperations
 Added documentation for the free functions
oriented_side(const Point_2& p, ....)
that accept a point and a polygon.  Documentation has been improved across the whole package.
Polygon Mesh Processing
 Added the class
CGAL::Polyhedral_envelope
, providing a way to quickly check if a primitive (point, segment, or triangle) is within a polyhedral envelope around a set of triangles. It is based on the work of Bolun Wang, Teseo Schneider, Yixin Hu, Marco Attene, and Daniele Panozzo. “Exact and efficient polyhedral envelope containment check.” (ACM Trans. Graph., 394, July 2020).  Added more functions in the visitor of the corefinement based methods to track all edge creations.
Surface Mesh Topology
 Added the function
CGAL::Surface_mesh_topology::Curves_on_surface_topology::is_homotopic_to_simple_cycle()
, which can be used to determine whehter a closed path on a surface mesh can be continously transformed to a cycle without self intersection.
Surface Mesh Simplification
 Added a filtering mechanism so that costly tests get only applied to the next candidate for the edge collapse.
 Added the class
Polyhedral_envelope_filter
, which enables to perform mesh simplification inside a polyhedral envelope of the input mesh.
2D Polyline Simplification
 When polylines have common subsequences of vertices, these subsequences may now be simplifified simultaneously.
dD Triangulations
 Added the function
insert_if_in_star()
to the classCGAL::Regular_triangulation
, which enables users to insert a pointp
in a regular triangulation on the condition thatp
appears postinsertion in the star of a userspecified, existing vertex.
2D and 3D Alpha Shapes
 Breaking change: The following deprecated classes have been removed:
Alpha_shape_euclidean_traits_2
,Weighted_alpha_shape_euclidean_traits_2
,Alpha_shape_euclidean_traits_3
, andWeighted_alpha_shape_euclidean_traits_3
. All CGAL kernel can be used directly as models of the concepts of the 2D and 3D Alpha Shape packages.
Classification
 Breaking change: the support for TensorFlow has been dropped; the
classifier
CGAL::TensorFlow::Neural_network_classifier
has been removed.