mirror of https://github.com/opencv/opencv.git
Open Source Computer Vision Library
https://opencv.org/
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
325 lines
10 KiB
325 lines
10 KiB
Planar Subdivisions (C API) |
|
============================ |
|
|
|
.. highlight:: c |
|
|
|
CvSubdiv2D |
|
---------- |
|
|
|
.. ocv:struct:: CvSubdiv2D |
|
|
|
Planar subdivision. |
|
|
|
:: |
|
|
|
#define CV_SUBDIV2D_FIELDS() \ |
|
CV_GRAPH_FIELDS() \ |
|
int quad_edges; \ |
|
int is_geometry_valid; \ |
|
CvSubdiv2DEdge recent_edge; \ |
|
CvPoint2D32f topleft; \ |
|
CvPoint2D32f bottomright; |
|
|
|
typedef struct CvSubdiv2D |
|
{ |
|
CV_SUBDIV2D_FIELDS() |
|
} |
|
CvSubdiv2D; |
|
|
|
.. |
|
|
|
Planar subdivision is the subdivision of a plane into a set of |
|
non-overlapped regions (facets) that cover the whole plane. The above |
|
structure describes a subdivision built on a 2D point set, where the points |
|
are linked together and form a planar graph, which, together with a few |
|
edges connecting the exterior subdivision points (namely, convex hull points) |
|
with infinity, subdivides a plane into facets by its edges. |
|
|
|
For every subdivision, there is a dual subdivision in which facets and |
|
points (subdivision vertices) swap their roles. This means that a facet is |
|
treated as a vertex (called a virtual point below) of the dual subdivision and |
|
the original subdivision vertices become facets. In the figure below, the |
|
original subdivision is marked with solid lines and dual subdivision - |
|
with dotted lines. |
|
|
|
.. image:: pics/subdiv.png |
|
|
|
OpenCV subdivides a plane into triangles using the Delaunay's |
|
algorithm. Subdivision is built iteratively starting from a dummy |
|
triangle that includes all the subdivision points for sure. In this |
|
case, the dual subdivision is a Voronoi diagram of the input 2D point set. The |
|
subdivisions can be used for the 3D piece-wise transformation of a plane, |
|
morphing, fast location of points on the plane, building special graphs |
|
(such as NNG,RNG), and so forth. |
|
|
|
CvQuadEdge2D |
|
------------ |
|
|
|
.. ocv:struct:: CvQuadEdge2D |
|
|
|
Quad-edge of a planar subdivision. |
|
|
|
:: |
|
|
|
/* one of edges within quad-edge, lower 2 bits is index (0..3) |
|
and upper bits are quad-edge pointer */ |
|
typedef long CvSubdiv2DEdge; |
|
|
|
/* quad-edge structure fields */ |
|
#define CV_QUADEDGE2D_FIELDS() \ |
|
int flags; \ |
|
struct CvSubdiv2DPoint* pt[4]; \ |
|
CvSubdiv2DEdge next[4]; |
|
|
|
typedef struct CvQuadEdge2D |
|
{ |
|
CV_QUADEDGE2D_FIELDS() |
|
} |
|
CvQuadEdge2D; |
|
|
|
.. |
|
|
|
Quad-edge is a basic element of a subdivision containing four edges (e, eRot, reversed e, and reversed eRot): |
|
|
|
.. image:: pics/quadedge.png |
|
|
|
CvSubdiv2DPoint |
|
--------------- |
|
|
|
.. ocv:struct:: CvSubdiv2DPoint |
|
|
|
Point of an original or dual subdivision. |
|
|
|
:: |
|
|
|
#define CV_SUBDIV2D_POINT_FIELDS()\ |
|
int flags; \ |
|
CvSubdiv2DEdge first; \ |
|
CvPoint2D32f pt; \ |
|
int id; |
|
|
|
#define CV_SUBDIV2D_VIRTUAL_POINT_FLAG (1 << 30) |
|
|
|
typedef struct CvSubdiv2DPoint |
|
{ |
|
CV_SUBDIV2D_POINT_FIELDS() |
|
} |
|
CvSubdiv2DPoint; |
|
|
|
.. |
|
|
|
* id |
|
This integer can be used to index auxiliary data associated with each vertex of the planar subdivision. |
|
|
|
CalcSubdivVoronoi2D |
|
------------------- |
|
Calculates the coordinates of the Voronoi diagram cells. |
|
|
|
.. ocv:cfunction:: void cvCalcSubdivVoronoi2D( CvSubdiv2D* subdiv ) |
|
.. ocv:pyoldfunction:: cv.CalcSubdivVoronoi2D(subdiv)-> None |
|
|
|
:param subdiv: Delaunay subdivision, in which all the points are already added. |
|
|
|
The function calculates the coordinates |
|
of virtual points. All virtual points corresponding to a vertex of the |
|
original subdivision form (when connected together) a boundary of the Voronoi |
|
cell at that point. |
|
|
|
ClearSubdivVoronoi2D |
|
-------------------- |
|
Removes all virtual points. |
|
|
|
.. ocv:cfunction:: void cvClearSubdivVoronoi2D( CvSubdiv2D* subdiv ) |
|
.. ocv:pyoldfunction:: cv.ClearSubdivVoronoi2D(subdiv)-> None |
|
|
|
:param subdiv: Delaunay subdivision. |
|
|
|
The function removes all of the virtual points. It |
|
is called internally in |
|
:ocv:cfunc:`CalcSubdivVoronoi2D` |
|
if the subdivision |
|
was modified after the previous call to the function. |
|
|
|
CreateSubdivDelaunay2D |
|
---------------------- |
|
Creates an empty Delaunay triangulation. |
|
|
|
.. ocv:cfunction:: CvSubdiv2D* cvCreateSubdivDelaunay2D( CvRect rect, CvMemStorage* storage ) |
|
.. ocv:pyoldfunction:: cv.CreateSubdivDelaunay2D(rect, storage) -> CvSubdiv2D |
|
|
|
:param rect: Rectangle that includes all of the 2D points that are to be added to the subdivision. |
|
|
|
:param storage: Container for the subdivision. |
|
|
|
The function creates an empty Delaunay |
|
subdivision where 2D points can be added using the function |
|
:ocv:cfunc:`SubdivDelaunay2DInsert` |
|
. All of the points to be added must be within |
|
the specified rectangle, otherwise a runtime error is raised. |
|
|
|
Note that the triangulation is a single large triangle that covers the given rectangle. Hence the three vertices of this triangle are outside the rectangle |
|
``rect`` |
|
. |
|
|
|
FindNearestPoint2D |
|
------------------ |
|
Finds the subdivision vertex closest to the given point. |
|
|
|
.. ocv:cfunction:: CvSubdiv2DPoint* cvFindNearestPoint2D( CvSubdiv2D* subdiv, CvPoint2D32f pt ) |
|
.. ocv:pyoldfunction:: cv.FindNearestPoint2D(subdiv, pt)-> point |
|
|
|
:param subdiv: Delaunay or another subdivision. |
|
|
|
:param pt: Input point. |
|
|
|
The function is another function that |
|
locates the input point within the subdivision. It finds the subdivision vertex that |
|
is the closest to the input point. It is not necessarily one of vertices |
|
of the facet containing the input point, though the facet (located using |
|
:ocv:cfunc:`Subdiv2DLocate` |
|
) is used as a starting |
|
point. The function returns a pointer to the found subdivision vertex. |
|
|
|
Subdiv2DEdgeDst |
|
--------------- |
|
Returns the edge destination. |
|
|
|
.. ocv:cfunction:: CvSubdiv2DPoint* cvSubdiv2DEdgeDst( CvSubdiv2DEdge edge ) |
|
.. ocv:pyoldfunction:: cv.Subdiv2DEdgeDst(edge)-> point |
|
|
|
:param edge: Subdivision edge (not a quad-edge). |
|
|
|
The function returns the edge destination. The |
|
returned pointer may be NULL if the edge is from a dual subdivision and |
|
the virtual point coordinates are not calculated yet. The virtual points |
|
can be calculated using the function |
|
:ocv:cfunc:`CalcSubdivVoronoi2D`. |
|
|
|
Subdiv2DGetEdge |
|
--------------- |
|
Returns one of the edges related to the given edge. |
|
|
|
.. ocv:cfunction:: CvSubdiv2DEdge cvSubdiv2DGetEdge( CvSubdiv2DEdge edge, CvNextEdgeType type ) |
|
.. ocv:pyoldfunction:: cv.Subdiv2DGetEdge(edge, type)-> CvSubdiv2DEdge |
|
|
|
:param edge: Subdivision edge (not a quad-edge). |
|
|
|
:param type: Parameter specifying which of the related edges to return. The following values are possible: |
|
|
|
* **CV_NEXT_AROUND_ORG** next around the edge origin ( ``eOnext`` on the picture below if ``e`` is the input edge) |
|
|
|
* **CV_NEXT_AROUND_DST** next around the edge vertex ( ``eDnext`` ) |
|
|
|
* **CV_PREV_AROUND_ORG** previous around the edge origin (reversed ``eRnext`` ) |
|
|
|
* **CV_PREV_AROUND_DST** previous around the edge destination (reversed ``eLnext`` ) |
|
|
|
* **CV_NEXT_AROUND_LEFT** next around the left facet ( ``eLnext`` ) |
|
|
|
* **CV_NEXT_AROUND_RIGHT** next around the right facet ( ``eRnext`` ) |
|
|
|
* **CV_PREV_AROUND_LEFT** previous around the left facet (reversed ``eOnext`` ) |
|
|
|
* **CV_PREV_AROUND_RIGHT** previous around the right facet (reversed ``eDnext`` ) |
|
|
|
.. image:: pics/quadedge.png |
|
|
|
The function returns one of the edges related to the input edge. |
|
|
|
Subdiv2DNextEdge |
|
---------------- |
|
Returns next edge around the edge origin. |
|
|
|
.. ocv:cfunction:: CvSubdiv2DEdge cvSubdiv2DNextEdge( CvSubdiv2DEdge edge ) |
|
.. ocv:pyoldfunction:: cv.Subdiv2DNextEdge(edge)-> CvSubdiv2DEdge |
|
|
|
:param edge: Subdivision edge (not a quad-edge). |
|
|
|
The function returns the next edge around the edge origin: |
|
``eOnext`` |
|
on the picture above if |
|
``e`` |
|
is the input edge). |
|
|
|
Subdiv2DLocate |
|
-------------- |
|
Returns the location of a point within a Delaunay triangulation. |
|
|
|
.. ocv:cfunction:: CvSubdiv2DPointLocation cvSubdiv2DLocate( CvSubdiv2D* subdiv, CvPoint2D32f pt, CvSubdiv2DEdge* edge, CvSubdiv2DPoint** vertex=NULL ) |
|
.. ocv:pyoldfunction:: cv.Subdiv2DLocate(subdiv, pt) -> (loc, where) |
|
|
|
:param subdiv: Delaunay or another subdivision. |
|
|
|
:param pt: Point to locate. |
|
|
|
:param edge: Output edge that the point belongs to or is located to the right of it. |
|
|
|
:param vertex: Optional output vertex double pointer the input point coincides with. |
|
|
|
The function locates the input point within the subdivision. There are five cases: |
|
|
|
* |
|
The point falls into some facet. The function returns |
|
``CV_PTLOC_INSIDE`` |
|
and |
|
``*edge`` |
|
will contain one of edges of the facet. |
|
|
|
* |
|
The point falls onto the edge. The function returns |
|
``CV_PTLOC_ON_EDGE`` |
|
and |
|
``*edge`` |
|
will contain this edge. |
|
|
|
* |
|
The point coincides with one of the subdivision vertices. The function returns |
|
``CV_PTLOC_VERTEX`` |
|
and |
|
``*vertex`` |
|
will contain a pointer to the vertex. |
|
|
|
* |
|
The point is outside the subdivision reference rectangle. The function returns |
|
``CV_PTLOC_OUTSIDE_RECT`` |
|
and no pointers are filled. |
|
|
|
* |
|
One of input arguments is invalid. A runtime error is raised or, if silent or "parent" error processing mode is selected, |
|
``CV_PTLOC_ERROR`` |
|
is returnd. |
|
|
|
Subdiv2DRotateEdge |
|
------------------ |
|
Returns another edge of the same quad-edge. |
|
|
|
.. ocv:cfunction:: CvSubdiv2DEdge cvSubdiv2DRotateEdge( CvSubdiv2DEdge edge, int rotate ) |
|
.. ocv:pyoldfunction:: cv.Subdiv2DRotateEdge(edge, rotate)-> CvSubdiv2DEdge |
|
|
|
:param edge: Subdivision edge (not a quad-edge). |
|
|
|
:param rotate: Parameter specifying which of the edges of the same quad-edge as the input one to return. The following values are possible: |
|
|
|
* **0** the input edge ( ``e`` on the picture below if ``e`` is the input edge) |
|
|
|
* **1** the rotated edge ( ``eRot`` ) |
|
|
|
* **2** the reversed edge (reversed ``e`` (in green)) |
|
|
|
* **3** the reversed rotated edge (reversed ``eRot`` (in green)) |
|
|
|
The function returns one of the edges of the same quad-edge as the input edge. |
|
|
|
SubdivDelaunay2DInsert |
|
---------------------- |
|
Inserts a single point into a Delaunay triangulation. |
|
|
|
.. ocv:cfunction:: CvSubdiv2DPoint* cvSubdivDelaunay2DInsert( CvSubdiv2D* subdiv, CvPoint2D32f pt) |
|
.. ocv:pyoldfunction:: cv.SubdivDelaunay2DInsert(subdiv, pt)-> point |
|
|
|
:param subdiv: Delaunay subdivision created by the function :ocv:cfunc:`CreateSubdivDelaunay2D`. |
|
|
|
:param pt: Inserted point. |
|
|
|
The function inserts a single point into a subdivision and modifies the subdivision topology appropriately. If a point with the same coordinates exists already, no new point is added. The function returns a pointer to the allocated point. No virtual point coordinates are calculated at this stage. |
|
|
|
|