uk.ac.starlink.ast
Class Region

java.lang.Object
  extended by uk.ac.starlink.ast.AstObject
      extended by uk.ac.starlink.ast.Mapping
          extended by uk.ac.starlink.ast.Frame
              extended by uk.ac.starlink.ast.Region
Direct Known Subclasses:
Box, Circle, CmpRegion, Ellipse, Interval, NullRegion, PointList, Polygon, Prism, Stc

public abstract class Region
extends Frame

Java interface to the AST Region class - represents a region within a coordinate system. This class provides the basic facilities for describing a region within a specified coordinate system. However, the Region class does not have a constructor function of its own, as it is simply a container class for a family of specialised sub-classes such as Circle, Box, etc, which implement Regions with particular shapes.

All sub-classes of Region require a Frame to be supplied when the Region is created. This Frame describes the coordinate system in which the Region is defined, and is referred to as the "encapsulated Frame" below. Constructors will also typically required one or more positions to be supplied which define the location and extent of the region. These positions must be supplied within the encapsulated Frame.

The Region class inherits from the Frame class, and so a Region can be supplied where-ever a Frame is expected. In these cases, supplying a Region is equivalent to supplying a reference to its encapsulated Frame. Thus all the methods of the Frame class can be used on the Region class. For instance, the astFormat function may be used on a Region to format an axis value.

In addition, since Frame inherits from Mapping, a Region is also a sort of Mapping. Transforming positions by supplying a Region to one of the astTran functions is the way to determine if a given position is inside or outside the Region. When used as a Mapping, most classes of Frame are equivalent to a UnitMap. However, the Region class modifies this behaviour so that a Region acts like a UnitMap only for input positions which are within the area represented by the Region. Input positions which are outside the area produce bad output values (i.e. the output values are equal to AST__BAD). This behaviour is the same for both the forward and the inverse transformation. In this sense the "inverse transformation" is not a true inverse of the forward transformation, since applying the forward transformation to a point outside the Region, and then applying the inverse transformation results, in a set of AST__BAD axis values rather than the original axis values. If required, the astRemoveRegions function can be used to remove the "masking" effect of any Regions contained within a compound Mapping or FrameSet. It does this by replacing each Region with a UnitMap or equivalent Frame (depending on the context in which the Region is used).

If the coordinate system represented by the Region is changed (by changing the values of one or more of the attribute which the Region inherits from its encapsulated Frame), the area represented by the Region is mapped into the new coordinate system. For instance, let's say a Circle (a subclass of Region) is created, a SkyFrame being supplied to the constructor so that the Circle describes a circular area on the sky in FK4 equatorial coordinates. Since Region inherits from Frame, the Circle will have a System attribute and this attribute will be set to "FK4". If the System attribute of the Region is then changed from FK4 to FK5, the circular area represented by the Region will automatically be mapped from the FK4 system into the FK5 system. In general, changing the coordinate system in this way may result in the region changing shape - for instance, a circle may change into an ellipse if the transformation from the old to the new coordinate system is linear but with different scales on each axis. Thus the specific class of a Region cannot be used as a guarantee of the shape in any particular coordinate system. If the astSimplify function is used on a Region, it will endeavour to return a new Region of a sub-class which accurately describes the shape in the current coordinate system of the Region (but this may not always be possible).

It is possible to negate an existing Region so that it represents all areas of the encapsulated Frame except for the area specified when the Region was created.

Licence

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public Licence as published by the Free Software Foundation; either version 2 of the Licence, or (at your option) any later version.

This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public Licence for more details.

You should have received a copy of the GNU General Public Licence along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street,Fifth Floor, Boston, MA 02110-1301, USA

See Also:
AST Region

Nested Class Summary
 
Nested classes/interfaces inherited from class uk.ac.starlink.ast.Mapping
Mapping.Interpolator, Mapping.Spreader
 
Field Summary
static int OVERLAP_INSIDE
          This region is completely inside the other one.
static int OVERLAP_NEGATE
          The other region is the exact negation of this one to within their uncertainties.
static int OVERLAP_NONE
          There is no overlap between this region and the other.
static int OVERLAP_OUTSIDE
          The other region is completely inside this one.
static int OVERLAP_PARTIAL
          There is partial overlap between this region and the other.
static int OVERLAP_SAME
          The regions are identical to within their uncertainties.
static int OVERLAP_UNKNOWN
          No overlap could be determined because the other region could not be mapped into the coordinate system of this one.
 
Fields inherited from class uk.ac.starlink.ast.Mapping
LINEAR_INTERPOLATOR, LINEAR_SPREADER, NEAREST_INTERPOLATOR, NEAREST_SPREADER
 
Fields inherited from class uk.ac.starlink.ast.AstObject
AST__BAD, AST__TUNULL, pointer
 
Method Summary
 boolean getAdaptive()
          Get should the area adapt to changes in the coordinate system.
 boolean getBounded()
          Get is the Region bounded.
 boolean getClosed()
          Get should the boundary be considered to be inside the region.
 double getFillFactor()
          Get fraction of the Region which is of interest.
 int getMeshSize()
          Get number of points used to represent the boundary of a Region.
 boolean getNegated()
          Get region negation flag.
 double[][] getRegionBounds()
          Returns the bounding box of Region.
 Frame getRegionFrame()
          Obtain a pointer to the encapsulated Frame within a Region.
 double[][] getRegionPoints()
          Returns the positions that define the given Region.
 Region getUnc(boolean def)
          Obtain uncertainty information from a Region.
 Region mapRegion(Mapping map, Frame frame)
          Transform a Region into a new Frame using a given Mapping.
 int mask(Mapping map, boolean inside, int ndim, int[] lbnd, int[] ubnd, Object in, Number val)
          Mask a region of a data grid.
 int maskB(Mapping map, boolean inside, int ndim, int[] lbnd, int[] ubnd, byte[] in, byte val)
          Masking method specific to byte data.
 int maskD(Mapping map, boolean inside, int ndim, int[] lbnd, int[] ubnd, double[] in, double val)
          Masking method specific to double data.
 int maskF(Mapping map, boolean inside, int ndim, int[] lbnd, int[] ubnd, float[] in, float val)
          Masking method specific to float data.
 int maskI(Mapping map, boolean inside, int ndim, int[] lbnd, int[] ubnd, int[] in, int val)
          Masking method specific to int data.
 int maskL(Mapping map, boolean inside, int ndim, int[] lbnd, int[] ubnd, long[] in, long val)
          Masking method specific to long data.
 int maskS(Mapping map, boolean inside, int ndim, int[] lbnd, int[] ubnd, short[] in, short val)
          Masking method specific to short data.
 void negate()
          Negate the area represented by a Region.
 int overlap(Region other)
          Test if two regions overlap each other.
 void setAdaptive(boolean adaptive)
          Set should the area adapt to changes in the coordinate system.
 void setClosed(boolean closed)
          Set should the boundary be considered to be inside the region.
 void setFillFactor(double fillFactor)
          Set fraction of the Region which is of interest.
 void setMeshSize(int meshSize)
          Set number of points used to represent the boundary of a Region.
 void setNegated(boolean negated)
          Set region negation flag.
 void setUnc(Region unc)
          Store uncertainty information in a Region.
 void showMesh(boolean format, String ttl)
          Display a mesh of points covering the surface of a Region.
 
Methods inherited from class uk.ac.starlink.ast.Frame
angle, axAngle, axDistance, axOffset, convert, distance, findFrame, format, getActiveUnit, getAlignSystem, getBottom, getDigits, getDigits, getDirection, getDomain, getDut1, getEpoch, getFormat, getLabel, getMatchEnd, getMaxAxes, getMinAxes, getNaxes, getNormUnit, getObsLat, getObsLon, getPermute, getPreserveAxes, getSymbol, getSystem, getTitle, getTop, getUnit, intersect, norm, offset, offset2, permAxes, pickAxes, resolve, setActiveUnit, setAlignSystem, setBottom, setDigits, setDigits, setDirection, setDomain, setDut1, setEpoch, setEpoch, setFormat, setLabel, setMatchEnd, setMaxAxes, setMinAxes, setObsLat, setObsLon, setPermute, setPreserveAxes, setSymbol, setSystem, setTitle, setTop, setUnit, unformat
 
Methods inherited from class uk.ac.starlink.ast.Mapping
decompose, getInvert, getNin, getNout, getReport, getTranForward, getTranInverse, invert, linearApprox, mapBox, mapSplit, rate, rebin, rebinD, rebinF, rebinI, resample, resampleB, resampleD, resampleF, resampleI, resampleL, resampleS, setInvert, setReport, simplify, tran1, tran2, tranGrid, tranN, tranP
 
Methods inherited from class uk.ac.starlink.ast.AstObject
annul, clear, copy, delete, equals, finalize, getAstConstantI, getB, getC, getD, getF, getI, getID, getIdent, getL, getNobject, getObjSize, getRefCount, hashCode, isThreaded, reportVersions, sameObject, set, setB, setC, setD, setF, setI, setID, setIdent, setL, show, test, tune
 
Methods inherited from class java.lang.Object
clone, getClass, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

OVERLAP_UNKNOWN

public static final int OVERLAP_UNKNOWN
No overlap could be determined because the other region could not be mapped into the coordinate system of this one.

See Also:
Constant Field Values

OVERLAP_NONE

public static final int OVERLAP_NONE
There is no overlap between this region and the other.

See Also:
Constant Field Values

OVERLAP_INSIDE

public static final int OVERLAP_INSIDE
This region is completely inside the other one.

See Also:
Constant Field Values

OVERLAP_OUTSIDE

public static final int OVERLAP_OUTSIDE
The other region is completely inside this one.

See Also:
Constant Field Values

OVERLAP_PARTIAL

public static final int OVERLAP_PARTIAL
There is partial overlap between this region and the other.

See Also:
Constant Field Values

OVERLAP_SAME

public static final int OVERLAP_SAME
The regions are identical to within their uncertainties.

See Also:
Constant Field Values

OVERLAP_NEGATE

public static final int OVERLAP_NEGATE
The other region is the exact negation of this one to within their uncertainties.

See Also:
Constant Field Values
Method Detail

getRegionBounds

public double[][] getRegionBounds()
Returns the bounding box of Region. This function returns the upper and lower limits of a box which just encompasses the supplied Region. The limits are returned as axis values within the Frame represented by the Region. The value of the Negated attribute is ignored (i.e. it is assumed that the Region has not been negated).

Notes

The value of the Negated attribute is ignored (i.e. it is assumed that he Region has not been negated). If an axis has no extent on an axis then the lower limit will be eturned larger than the upper limit. Note, this is different to an xis which has a constant value (in which case both lower and upper imit will be returned set to the constant value).

Returns:
A two-element array of naxes-element arrays giving the bounds of a box which contains this region. The first element is the lower bounds, and the second element is the upper bounds. If there is no limit on a lower/upper bound on a given axis, the corresponding value will be the lowest negative/highest positive possible value.
Throws:
AstException - if an error occurred in the AST library

getRegionFrame

public Frame getRegionFrame()
Obtain a pointer to the encapsulated Frame within a Region. This function returns a pointer to the Frame represented by a Region.

Notes


- A null Object pointer (AST__NULL) will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.

Returns:
A pointer to a deep copy of the Frame represented by the Region. Using this pointer to modify the Frame will have no effect on the Region. To modify the Region, use the Region pointer directly.
Throws:
AstException - if an error occurred in the AST library

getRegionPoints

public double[][] getRegionPoints()
Returns the positions that define the given Region. This function returns the axis values at the points that define the supplied Region. The particular meaning of these points will depend on the type of class supplied, as listed below under "Applicability:".

Notes


- If the coordinate system represented by the Region has been changed since it was first created, the returned axis values refer to the new (changed) coordinate system, rather than the original coordinate system. Note however that if the transformation from original to new coordinate system is non-linear, the shape within the new coordinate system may be distorted, and so may not match that implied by the name of the Region subclass (Circle, Box, etc).

Returns:
The address of the first element in a 2-dimensional array of shape "[maxcoord][maxpoint]", in which to return the coordinate values at the positions that define the Region. These are stored such that the value of coordinate number "coord" for point number "point" is found in element "points[coord][point]".
Throws:
AstException - if an error occurred in the AST library

getUnc

public Region getUnc(boolean def)
Obtain uncertainty information from a Region. This function returns a Region which represents the uncertainty associated with positions within the supplied Region. See astSetUnc for more information about Region uncertainties and their use.

Notes


- If uncertainty information is associated with a Region, and the coordinate system described by the Region is subsequently changed (e.g. by changing the value of its System attribute, or using the astMapRegion function), then the uncertainty information returned by this function will be modified so that it refers to the coordinate system currently described by the supplied Region.
- A null Object pointer (NULL) will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.

Parameters:
def - Controls what is returned if no uncertainty information has been associated explicitly with the supplied Region. If a non-zero value is supplied, then the default uncertainty Region used internally within AST is returned (see "Applicability" below). If zero is supplied, then NULL will be returned (without error).
Returns:
A pointer to a Region describing the uncertainty in the supplied Region.
Throws:
AstException - if an error occurred in the AST library

mapRegion

public Region mapRegion(Mapping map,
                        Frame frame)
Transform a Region into a new Frame using a given Mapping. This function returns a pointer to a new Region which corresponds to supplied Region described by some other specified coordinate system. A Mapping is supplied which transforms positions between the old and new coordinate systems. The new Region may not be of the same class as the original region.

Notes


- The uncertainty associated with the supplied Region is modified using the supplied Mapping.
- A null Object pointer (AST__NULL) will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.

Parameters:
map - Pointer to a Mapping which transforms positions from the coordinate system represented by the supplied Region to the coordinate system specified by "frame". The supplied Mapping should define both forward and inverse transformations, and these transformations should form a genuine inverse pair. That is, transforming a position using the forward transformation and then using the inverse transformation should produce the original input position. Some Mapping classes (such as PermMap, MathMap, SphMap) can result in Mappings for which this is not true.
frame - Pointer to a Frame describing the coordinate system in which the new Region is required.
Returns:
A pointer to a new Region. This Region will represent the area within the coordinate system specified by "frame" which corresponds to the supplied Region.
Throws:
AstException - if an error occurred in the AST library

negate

public void negate()
Negate the area represented by a Region. This function negates the area represented by a Region. That is, points which were previously inside the region will then be outside, and points which were outside will be inside. This is acomplished by toggling the state of the Negated attribute for the supplied region.

Throws:
AstException - if an error occurred in the AST library

overlap

public int overlap(Region other)
Test if two regions overlap each other. This function returns an integer value indicating if the two supplied Regions overlap. The two Regions are converted to a commnon coordinate system before performing the check. If this conversion is not possible (for instance because the two Regions represent areas in different domains), then the check cannot be performed and a zero value is returned to indicate this.

Notes


- The returned values 5 and 6 do not check the value of the Closed attribute in the two Regions.
- A value of zero will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.

Parameters:
other - Other region for comparison with this one
Returns:
value indicating overlap status - it will be one of the OVERLAP_* static final integers defined in the Region class
Throws:
AstException - if an error occurred in the AST library

mask

public int mask(Mapping map,
                boolean inside,
                int ndim,
                int[] lbnd,
                int[] ubnd,
                Object in,
                Number val)
Mask a region of a data grid. This is a set of functions for masking out regions within gridded data (e.g. an image). The functions modifies a given data grid by assigning a specified value to all samples which are inside (or outside if "inside" is zero) the specified Region.

You should use a masking function which matches the numerical type of the data you are processing by replacing in the generic function name astMask by an appropriate 1- or 2-character type code. For example, if you are masking data with type "float", you should use the function astMaskF (see the "Data Type Codes" section below for the codes appropriate to other numerical types).

Notes


- A value of zero will be returned if this function is invoked with the global error status set, or if it should fail for any reason.

Parameters:
map - Pointer to a Mapping. The forward transformation should map positions in the coordinate system of the supplied Region into pixel coordinates as defined by the "lbnd" and "ubnd" parameters. A NULL pointer can be supplied if the coordinate system of the supplied Region corresponds to pixel coordinates. This is equivalent to supplying a UnitMap.

The number of inputs for this Mapping (as given by its Nin attribute) should match the number of axes in the supplied Region (as given by the Naxes attribute of the Region). The number of outputs for the Mapping (as given by its Nout attribute) should match the number of grid dimensions given by the value of "ndim" below.

inside - A boolean value which indicates which pixel are to be masked. If a non-zero value is supplied, then all grid pixels with centres inside the supplied Region are assigned the value given by "val", and all other pixels are left unchanged. If zero is supplied, then all grid pixels with centres not inside the supplied Region are assigned the value given by "val", and all other pixels are left unchanged. Note, the Negated attribute of the Region is used to determine which pixel are inside the Region and which are outside. So the inside of a Region which has not been negated is the same as the outside of the corresponding negated Region.

For types of Region such as PointList which have zero volume, pixel centres will rarely fall exactly within the Region. For this reason, the inclusion criterion is changed for zero-volume Regions so that pixels are included (or excluded) if any part of the Region passes through the pixel. For a PointList, this means that pixels are included (or excluded) if they contain at least one of the points listed in the PointList.

ndim - The number of dimensions in the input grid. This should be at least one.
lbnd - Pointer to an array of integers, with "ndim" elements, containing the coordinates of the centre of the first pixel in the input grid along each dimension.
ubnd - Pointer to an array of integers, with "ndim" elements, containing the coordinates of the centre of the last pixel in the input grid along each dimension.

Note that "lbnd" and "ubnd" together define the shape and size of the input grid, its extent along a particular (j'th) dimension being ubnd[j]-lbnd[j]+1 (assuming the index "j" to be zero-based). They also define the input grid's coordinate system, each pixel having unit extent along each dimension with integral coordinate values at its centre.

in - Pointer to an array, with one element for each pixel in the input grid, containing the data to be masked. The numerical type of this array should match the 1- or 2-character type code appended to the function name (e.g. if you are using astMaskF, the type of each array element should be "float").

The storage order of data within this array should be such that the index of the first grid dimension varies most rapidly and that of the final dimension least rapidly (i.e. Fortran array indexing is used).

On exit, the samples specified by "inside" are set to the value of "val". All other samples are left unchanged.

val - specifies the value used to flag the masked data. This should be an object of the wrapper class corresponding to the array type of the in array.
Returns:
The number of pixels to which a value of "badval" has been assigned.
Throws:
AstException - if an error occurred in the AST library

maskB

public int maskB(Mapping map,
                 boolean inside,
                 int ndim,
                 int[] lbnd,
                 int[] ubnd,
                 byte[] in,
                 byte val)
Masking method specific to byte data.

See Also:
mask(uk.ac.starlink.ast.Mapping, boolean, int, int[], int[], java.lang.Object, java.lang.Number)

maskS

public int maskS(Mapping map,
                 boolean inside,
                 int ndim,
                 int[] lbnd,
                 int[] ubnd,
                 short[] in,
                 short val)
Masking method specific to short data.

See Also:
mask(uk.ac.starlink.ast.Mapping, boolean, int, int[], int[], java.lang.Object, java.lang.Number)

maskI

public int maskI(Mapping map,
                 boolean inside,
                 int ndim,
                 int[] lbnd,
                 int[] ubnd,
                 int[] in,
                 int val)
Masking method specific to int data.

See Also:
mask(uk.ac.starlink.ast.Mapping, boolean, int, int[], int[], java.lang.Object, java.lang.Number)

maskL

public int maskL(Mapping map,
                 boolean inside,
                 int ndim,
                 int[] lbnd,
                 int[] ubnd,
                 long[] in,
                 long val)
Masking method specific to long data.

See Also:
mask(uk.ac.starlink.ast.Mapping, boolean, int, int[], int[], java.lang.Object, java.lang.Number)

maskF

public int maskF(Mapping map,
                 boolean inside,
                 int ndim,
                 int[] lbnd,
                 int[] ubnd,
                 float[] in,
                 float val)
Masking method specific to float data.

See Also:
mask(uk.ac.starlink.ast.Mapping, boolean, int, int[], int[], java.lang.Object, java.lang.Number)

maskD

public int maskD(Mapping map,
                 boolean inside,
                 int ndim,
                 int[] lbnd,
                 int[] ubnd,
                 double[] in,
                 double val)
Masking method specific to double data.

See Also:
mask(uk.ac.starlink.ast.Mapping, boolean, int, int[], int[], java.lang.Object, java.lang.Number)

setUnc

public void setUnc(Region unc)
Store uncertainty information in a Region. Each Region (of any class) can have an "uncertainty" which specifies the uncertainties associated with the boundary of the Region. This information is supplied in the form of a second Region. The uncertainty in any point on the boundary of a Region is found by shifting the associated "uncertainty" Region so that it is centred at the boundary point being considered. The area covered by the shifted uncertainty Region then represents the uncertainty in the boundary position. The uncertainty is assumed to be the same for all points.

The uncertainty is usually specified when the Region is created, but this function allows it to be changed at any time.

Parameters:
unc - Pointer to the new uncertainty Region. This must be of a class for which all instances are centro-symetric (e.g. Box, Circle, Ellipse, etc.) or be a Prism containing centro-symetric component Regions. A deep copy of the supplied Region will be taken, so subsequent changes to the uncertainty Region using the supplied pointer will have no effect on the Region "this".
Throws:
AstException - if an error occurred in the AST library

showMesh

public void showMesh(boolean format,
                     String ttl)
Display a mesh of points covering the surface of a Region. This function writes a table to standard output containing the axis values at a mesh of points covering the surface of the supplied Region. Each row of output contains a tab-separated list of axis values, one for each axis in the Frame encapsulated by the Region. The number of points in the mesh is determined by the MeshSize attribute.

The table is preceeded by a given title string, and followed by a single line containing the word "ENDMESH".

Parameters:
format - A boolean value indicating if the displayed axis values should be formatted according to the Format attribute associated with the Frame's axis. Otherwise, they are displayed as simple floating point values.
ttl - A title to display before displaying the first position.
Throws:
AstException - if an error occurred in the AST library

getAdaptive

public boolean getAdaptive()
Get should the area adapt to changes in the coordinate system. The coordinate system represented by a Region may be changed by assigning new values to attributes such as System, Unit, etc. For instance, a Region representing an area on the sky in ICRS coordinates may have its System attribute changed so that it represents (say) Galactic coordinates instead of ICRS. This attribute controls what happens when the coordinate system represented by a Region is changed in this way.

If Adaptive is non-zero (the default), then area represented by the Region adapts to the new coordinate system. That is, the numerical values which define the area represented by the Region are changed by mapping them from the old coordinate system into the new coordinate system. Thus the Region continues to represent the same physical area.

If Adaptive is zero, then area represented by the Region does not adapt to the new coordinate system. That is, the numerical values which define the area represented by the Region are left unchanged. Thus the physical area represented by the Region will usually change.

As an example, consider a Region describe a range of wavelength from 2000 Angstrom to 4000 Angstrom. If the Unit attribute for the Region is changed from Angstrom to "nm" (nanometre), what happens depends on the setting of Adaptive. If Adaptive is non-zero, the Mapping from the old to the new coordinate system is found. In this case it is a simple scaling by a factor of 0.1 (since 1 Angstrom is 0.1 nm). This Mapping is then used to modify the numerical values within the Region, changing 2000 to 200 and 4000 to 400. Thus the modified region represents 200 nm to 400 nm, the same physical space as the original 2000 Angstrom to 4000 Angstrom. However, if Adaptive had been zero, then the numerical values would not have been changed, resulting in the final Region representing 2000 nm to 4000 nm.

Setting Adaptive to zero can be necessary if you want correct inaccurate attribute settings in an existing Region. For instance, when creating a Region you may not know what Epoch value to use, so you would leave Epoch unset resulting in some default value being used. If at some later point in the application, the correct Epoch value is determined, you could assign the correct value to the Epoch attribute. However, you would first need to set Adaptive temporarily to zero, because otherwise the area represented by the Region would be Mapped from the spurious default Epoch to the new correct Epoch, which is not what is required.

Returns:
this object's Adaptive attribute

setAdaptive

public void setAdaptive(boolean adaptive)
Set should the area adapt to changes in the coordinate system. The coordinate system represented by a Region may be changed by assigning new values to attributes such as System, Unit, etc. For instance, a Region representing an area on the sky in ICRS coordinates may have its System attribute changed so that it represents (say) Galactic coordinates instead of ICRS. This attribute controls what happens when the coordinate system represented by a Region is changed in this way.

If Adaptive is non-zero (the default), then area represented by the Region adapts to the new coordinate system. That is, the numerical values which define the area represented by the Region are changed by mapping them from the old coordinate system into the new coordinate system. Thus the Region continues to represent the same physical area.

If Adaptive is zero, then area represented by the Region does not adapt to the new coordinate system. That is, the numerical values which define the area represented by the Region are left unchanged. Thus the physical area represented by the Region will usually change.

As an example, consider a Region describe a range of wavelength from 2000 Angstrom to 4000 Angstrom. If the Unit attribute for the Region is changed from Angstrom to "nm" (nanometre), what happens depends on the setting of Adaptive. If Adaptive is non-zero, the Mapping from the old to the new coordinate system is found. In this case it is a simple scaling by a factor of 0.1 (since 1 Angstrom is 0.1 nm). This Mapping is then used to modify the numerical values within the Region, changing 2000 to 200 and 4000 to 400. Thus the modified region represents 200 nm to 400 nm, the same physical space as the original 2000 Angstrom to 4000 Angstrom. However, if Adaptive had been zero, then the numerical values would not have been changed, resulting in the final Region representing 2000 nm to 4000 nm.

Setting Adaptive to zero can be necessary if you want correct inaccurate attribute settings in an existing Region. For instance, when creating a Region you may not know what Epoch value to use, so you would leave Epoch unset resulting in some default value being used. If at some later point in the application, the correct Epoch value is determined, you could assign the correct value to the Epoch attribute. However, you would first need to set Adaptive temporarily to zero, because otherwise the area represented by the Region would be Mapped from the spurious default Epoch to the new correct Epoch, which is not what is required.

Parameters:
adaptive - the Adaptive attribute of this object

getNegated

public boolean getNegated()
Get region negation flag. This attribute controls whether a Region represents the "inside" or the "outside" of the area which was supplied when the Region was created. If the attribute value is zero (the default), the Region represents the inside of the original area. However, if it is non-zero, it represents the outside of the original area. The value of this attribute may be toggled using the astNegate function.

Note, whether the boundary is considered to be inside the Region or not is controlled by the Closed attribute. Changing the value of the Negated attribute does not change the value of the Closed attribute. Thus, if Region is closed, then the boundary of the Region will be inside the Region, whatever the setting of the Negated attribute.

Returns:
this object's Negated attribute

setNegated

public void setNegated(boolean negated)
Set region negation flag. This attribute controls whether a Region represents the "inside" or the "outside" of the area which was supplied when the Region was created. If the attribute value is zero (the default), the Region represents the inside of the original area. However, if it is non-zero, it represents the outside of the original area. The value of this attribute may be toggled using the astNegate function.

Note, whether the boundary is considered to be inside the Region or not is controlled by the Closed attribute. Changing the value of the Negated attribute does not change the value of the Closed attribute. Thus, if Region is closed, then the boundary of the Region will be inside the Region, whatever the setting of the Negated attribute.

Parameters:
negated - the Negated attribute of this object

getClosed

public boolean getClosed()
Get should the boundary be considered to be inside the region. This attribute controls whether points on the boundary of a Region are considered to be inside or outside the region. If the attribute value is non-zero (the default), points on the boundary are considered to be inside the region (that is, the Region is "closed"). However, if the attribute value is zero, points on the bounary are considered to be outside the region.

Returns:
this object's Closed attribute

setClosed

public void setClosed(boolean closed)
Set should the boundary be considered to be inside the region. This attribute controls whether points on the boundary of a Region are considered to be inside or outside the region. If the attribute value is non-zero (the default), points on the boundary are considered to be inside the region (that is, the Region is "closed"). However, if the attribute value is zero, points on the bounary are considered to be outside the region.

Parameters:
closed - the Closed attribute of this object

getMeshSize

public int getMeshSize()
Get number of points used to represent the boundary of a Region. This attribute controls how many points are used when creating a mesh of points covering the boundary or volume of a Region. Such a mesh is returned by the astGetRegionMesh method. The boundary mesh is also used when testing for overlap between two Regions: each point in the bomdary mesh of the first Region is checked to see if it is inside or outside the second Region. Thus, the reliability of the overlap check depends on the value assigned to this attribute. If the value used is very low, it is possible for overlaps to go unnoticed. High values produce more reliable results, but can result in the overlap test being very slow. The default value is 200 for two dimensional Regions and 2000 for three or more dimensional Regions (this attribute is not used for 1-dimensional regions since the boundary of a simple 1-d Region can only ever have two points). A value of five is used if the supplied value is less than five.

Returns:
this object's MeshSize attribute

setMeshSize

public void setMeshSize(int meshSize)
Set number of points used to represent the boundary of a Region. This attribute controls how many points are used when creating a mesh of points covering the boundary or volume of a Region. Such a mesh is returned by the astGetRegionMesh method. The boundary mesh is also used when testing for overlap between two Regions: each point in the bomdary mesh of the first Region is checked to see if it is inside or outside the second Region. Thus, the reliability of the overlap check depends on the value assigned to this attribute. If the value used is very low, it is possible for overlaps to go unnoticed. High values produce more reliable results, but can result in the overlap test being very slow. The default value is 200 for two dimensional Regions and 2000 for three or more dimensional Regions (this attribute is not used for 1-dimensional regions since the boundary of a simple 1-d Region can only ever have two points). A value of five is used if the supplied value is less than five.

Parameters:
meshSize - the MeshSize attribute of this object

getFillFactor

public double getFillFactor()
Get fraction of the Region which is of interest. This attribute indicates the fraction of the Region which is of interest. AST does not use this attribute internally for any purpose. Typically, it could be used to indicate the fraction of the Region for which data is available.

The supplied value must be in the range 0.0 to 1.0, and the default value is 1.0 (except as noted below).

Returns:
this object's FillFactor attribute

setFillFactor

public void setFillFactor(double fillFactor)
Set fraction of the Region which is of interest. This attribute indicates the fraction of the Region which is of interest. AST does not use this attribute internally for any purpose. Typically, it could be used to indicate the fraction of the Region for which data is available.

The supplied value must be in the range 0.0 to 1.0, and the default value is 1.0 (except as noted below).

Parameters:
fillFactor - the FillFactor attribute of this object

getBounded

public boolean getBounded()
Get is the Region bounded. This is a read-only attribute indicating if the Region is bounded. A Region is bounded if it is contained entirely within some finite-size bounding box.

Returns:
this object's Bounded attribute


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