lsst::sphgeom::Region Class Reference

Region is a minimal interface for 2-dimensional regions on the unit sphere. More...

#include <Region.h>

Inheritance diagram for lsst::sphgeom::Region:

Public Member Functions
virtual	~Region ()
virtual std::unique_ptr< Region >	clone () const =0
	clone returns a deep copy of this region. More...
virtual Box	getBoundingBox () const =0
	getBoundingBox returns a bounding-box for this region. More...
virtual Box3d	getBoundingBox3d () const =0
	getBoundingBox3d returns a 3-dimensional bounding-box for this region. More...
virtual Circle	getBoundingCircle () const =0
	getBoundingCircle returns a bounding-circle for this region. More...
virtual bool	contains (UnitVector3d const &) const =0
	contains tests whether the given unit vector is inside this region. More...
virtual std::vector< uint8_t >	encode () const =0
	encode serializes this region into an opaque byte string. More...
virtual Relationship	relate (Region const &) const =0
virtual Relationship	relate (Box const &) const =0
virtual Relationship	relate (Circle const &) const =0
virtual Relationship	relate (ConvexPolygon const &) const =0
virtual Relationship	relate (Ellipse const &) const =0

Static Public Member Functions
static std::unique_ptr< Region >	decode (std::vector< uint8_t > const &s)
static std::unique_ptr< Region >	decode (uint8_t const *buffer, size_t n)

Detailed Description

Region is a minimal interface for 2-dimensional regions on the unit sphere.

It provides three core pieces of functionality:

• It allows a region to be approximated with a simpler one.
• It allows for inexact (but conservative) computation of the spatial relationships between two regions.
• It provides transformation between objects and binary strings.

Given a pixelization of the unit sphere with pixels that can be bounded by Regions, this provides all the necessary functionality for determining which pixels may intersect a Region.

When implementing a new concrete region subclass R, the Region interface should be extended with:

virtual Relationship relate(R const &) const = 0;

All other Region subclasses must then implement this method. In addition, R is expected to contain the following implementation of the generic relate method:

virtual Relationship relate(Region const & r) const {
    return invert(r.relate(*this));
}

where invert is defined in Relationship.h.

Given two Region references r1 and r2 of type R1 and R2, the net effect is that r1.relate(r2) will end up calling R2::relate(R1 const &). In other words, the call is polymorphic in the types of both r1 and r2.

One negative consequence of this design is that one cannot implement new Region types outside of this library.

Definition at line 79 of file Region.h.

Constructor & Destructor Documentation

~Region()

virtual lsst::sphgeom::Region::~Region ( )

inlinevirtual

Definition at line 81 of file Region.h.

{}

Member Function Documentation

clone()

virtual std::unique_ptr<Region> lsst::sphgeom::Region::clone ( ) const

pure virtual

clone returns a deep copy of this region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

contains()

virtual bool lsst::sphgeom::Region::contains ( UnitVector3d const &  ) const

pure virtual

contains tests whether the given unit vector is inside this region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

decode() [1/2]

static std::unique_ptr<Region> lsst::sphgeom::Region::decode ( std::vector< uint8_t > const &  s )

inlinestatic

decode deserializes a Region from a byte string produced by encode.

Definition at line 129 of file Region.h.

                                                                      {
        return decode(s.data(), s.size());
    }

decode() [2/2]

std::unique_ptr< Region > lsst::sphgeom::Region::decode ( uint8_t const *  buffer, size_t  n  )

static

decode deserializes a Region from a byte string produced by encode.

Definition at line 39 of file Region.cc.

                                                                     {
    if (buffer == nullptr || n == 0) {
        throw std::runtime_error("Byte-string is not an encoded Region");
    }
    uint8_t type = *buffer;
    if (type == Box::TYPE_CODE) {
        return Box::decode(buffer, n);
    } else if (type == Circle::TYPE_CODE) {
        return Circle::decode(buffer, n);
    } else if (type == ConvexPolygon::TYPE_CODE) {
        return ConvexPolygon::decode(buffer, n);
    } else if (type == Ellipse::TYPE_CODE) {
        return Ellipse::decode(buffer, n);
    }
    throw std::runtime_error("Byte-string is not an encoded Region");
}

encode()

virtual std::vector<uint8_t> lsst::sphgeom::Region::encode ( ) const

pure virtual

encode serializes this region into an opaque byte string.

Byte strings emitted by encode can be deserialized with decode.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

getBoundingBox()

virtual Box lsst::sphgeom::Region::getBoundingBox ( ) const

pure virtual

getBoundingBox returns a bounding-box for this region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

getBoundingBox3d()

virtual Box3d lsst::sphgeom::Region::getBoundingBox3d ( ) const

pure virtual

getBoundingBox3d returns a 3-dimensional bounding-box for this region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

getBoundingCircle()

virtual Circle lsst::sphgeom::Region::getBoundingCircle ( ) const

pure virtual

getBoundingCircle returns a bounding-circle for this region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

relate() [1/5]

virtual Relationship lsst::sphgeom::Region::relate ( Box const &  ) const

pure virtual

relate computes the spatial relationships between this region A and another region B. The return value S is a bitset with the following properties:

• Bit S & DISJOINT is set only if A and B do not have any points in common.
• Bit S & CONTAINS is set only if A contains all points in B.
• Bit S & WITHIN is set only if B contains all points in A.

Said another way: if the CONTAINS, WITHIN or DISJOINT bit is set, then the corresponding spatial relationship between the two regions holds conclusively. If it is not set, the relationship may or may not hold.

These semantics allow for conservative relationship computations. In particular, a Region may choose to implement relate by replacing itself and/or the argument with a simplified bounding region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

relate() [2/5]

virtual Relationship lsst::sphgeom::Region::relate ( Circle const &  ) const

pure virtual

relate computes the spatial relationships between this region A and another region B. The return value S is a bitset with the following properties:

• Bit S & DISJOINT is set only if A and B do not have any points in common.
• Bit S & CONTAINS is set only if A contains all points in B.
• Bit S & WITHIN is set only if B contains all points in A.

Said another way: if the CONTAINS, WITHIN or DISJOINT bit is set, then the corresponding spatial relationship between the two regions holds conclusively. If it is not set, the relationship may or may not hold.

These semantics allow for conservative relationship computations. In particular, a Region may choose to implement relate by replacing itself and/or the argument with a simplified bounding region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

relate() [3/5]

virtual Relationship lsst::sphgeom::Region::relate ( ConvexPolygon const &  ) const

pure virtual

relate computes the spatial relationships between this region A and another region B. The return value S is a bitset with the following properties:

• Bit S & DISJOINT is set only if A and B do not have any points in common.
• Bit S & CONTAINS is set only if A contains all points in B.
• Bit S & WITHIN is set only if B contains all points in A.

Said another way: if the CONTAINS, WITHIN or DISJOINT bit is set, then the corresponding spatial relationship between the two regions holds conclusively. If it is not set, the relationship may or may not hold.

These semantics allow for conservative relationship computations. In particular, a Region may choose to implement relate by replacing itself and/or the argument with a simplified bounding region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

relate() [4/5]

virtual Relationship lsst::sphgeom::Region::relate ( Ellipse const &  ) const

pure virtual

relate computes the spatial relationships between this region A and another region B. The return value S is a bitset with the following properties:

• Bit S & DISJOINT is set only if A and B do not have any points in common.
• Bit S & CONTAINS is set only if A contains all points in B.
• Bit S & WITHIN is set only if B contains all points in A.

Said another way: if the CONTAINS, WITHIN or DISJOINT bit is set, then the corresponding spatial relationship between the two regions holds conclusively. If it is not set, the relationship may or may not hold.

These semantics allow for conservative relationship computations. In particular, a Region may choose to implement relate by replacing itself and/or the argument with a simplified bounding region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

relate() [5/5]

virtual Relationship lsst::sphgeom::Region::relate ( Region const &  ) const

pure virtual

relate computes the spatial relationships between this region A and another region B. The return value S is a bitset with the following properties:

• Bit S & DISJOINT is set only if A and B do not have any points in common.
• Bit S & CONTAINS is set only if A contains all points in B.
• Bit S & WITHIN is set only if B contains all points in A.

Said another way: if the CONTAINS, WITHIN or DISJOINT bit is set, then the corresponding spatial relationship between the two regions holds conclusively. If it is not set, the relationship may or may not hold.

These semantics allow for conservative relationship computations. In particular, a Region may choose to implement relate by replacing itself and/or the argument with a simplified bounding region.

Implemented in lsst::sphgeom::Box, lsst::sphgeom::Ellipse, lsst::sphgeom::Circle, and lsst::sphgeom::ConvexPolygon.

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The documentation for this class was generated from the following files:

• /j/snowflake/release/lsstsw/stack/1a1d771/Linux64/sphgeom/20.0.0/include/lsst/sphgeom/Region.h
• /j/snowflake/release/lsstsw/stack/1a1d771/Linux64/sphgeom/20.0.0/src/Region.cc