PrecisionModel class

Specifies the precision model of the {@link Coordinate}s in a {@link Geometry}. In other words, specifies the grid of allowable points for all Geometrys.

The {@link #makePrecise(Coordinate)} method allows rounding a coordinate to a "precise" value; that is, one whose precision is known exactly.

Coordinates are assumed to be precise in geometries. That is, the coordinates are assumed to be rounded to the precision model given for the geometry. JTS input routines automatically round coordinates to the precision model before creating Geometries. All internal operations assume that coordinates are rounded to the precision model. Constructive methods (such as bool operations) always round computed coordinates to the appropriate precision model.

Currently three types of precision model are supported:

FLOATING - represents full double precision floating point. This is the default precision model used in JTS
FLOATING_SINGLE - represents single precision floating point.
FIXED - represents a model with a fixed number of decimal places. A Fixed Precision Model is specified by a scale factor. The scale factor specifies the size of the grid which numbers are rounded to. Input coordinates are mapped to fixed coordinates according to the following equations:
- jtsPt.x = round( (inputPt.x * scale ) / scale
- jtsPt.y = round( (inputPt.y * scale ) / scale

For example, to specify 3 decimal places of precision, use a scale factor of 1000. To specify -3 decimal places of precision (i.e. rounding to the nearest 1000), use a scale factor of 0.001.

Coordinates are represented internally as Java double-precision values. Since Java uses the IEEE-394 floating point standard, this provides 53 bits of precision. (Thus the maximum precisely representable integer is 9,007,199,254,740,992 - or almost 16 decimal digits of precision).

JTS binary methods currently do not handle inputs which have different precision models. The precision model of any constructed geometric value is undefined.

@version 1.7

Implemented types

Comparable

Constructors

PrecisionModel(): Creates a PrecisionModel with a default precision of FLOATING.
PrecisionModel.fixedPrecision(double scale): Creates a PrecisionModel that specifies Fixed precision. Fixed-precision coordinates are represented as precise internal coordinates, which are rounded to the grid defined by the scale factor.
PrecisionModel.fromPrecisionModel(PrecisionModel pm): Copy constructor to create a new PrecisionModel from an existing one.
PrecisionModel.fromType(Type modelType): Creates a PrecisionModel that specifies an explicit precision model type. If the model type is FIXED the scale factor will default to 1.

Properties

hashCode → int: The hash code for this object.
no setterinherited
modelType ↔ Type: The type of PrecisionModel this represents.
getter/setter pair
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
scale ↔ double: The scale factor which determines the number of decimal places in fixed precision.
getter/setter pair

Methods

compareTo(dynamic o) → int: Compares this {@link PrecisionModel} object with the specified object for order. A PrecisionModel is greater than another if it provides greater precision. The comparison is based on the value returned by the {@link #getMaximumSignificantDigits} method. This comparison is not strictly accurate when comparing floating precision models to fixed models; however, it is correct when both models are either floating or fixed.
override
equals(Object other) → bool
getMaximumSignificantDigits() → int: Returns the maximum number of significant digits provided by this precision model. Intended for use by routines which need to print out decimal representations of precise values (such as {@link WKTWriter}).
getScale() → double: Returns the scale factor used to specify a fixed precision model. The number of decimal places of precision is equal to the base-10 logarithm of the scale factor. Non-integral and negative scale factors are supported. Negative scale factors indicate that the places of precision is to the left of the decimal point.
getType() → Type: Gets the type of this precision model @return the type of this precision model @see Type
isFloating() → bool: Tests whether the precision model supports floating point @return true if the precision model supports floating point
makeCoordinatePrecise(Coordinate coord) → void: Rounds a Coordinate to the PrecisionModel grid.
makePrecise(double val) → double: Rounds a numeric value to the PrecisionModel grid. Asymmetric Arithmetic Rounding is used, to provide uniform rounding behaviour no matter where the number is on the number line.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
setScale(double scale) → void: Sets the multiplying factor used to obtain a precise coordinate. This method is because PrecisionModel is an immutable (value) type.
toString() → String: A string representation of this object.
override

Operators

operator ==(Object other) → bool: The equality operator.
inherited

Static Properties

FIXED → Type: Fixed Precision indicates that coordinates have a fixed number of decimal places. The number of decimal places is determined by the log10 of the scale factor.
final
FLOATING → Type: Floating precision corresponds to the standard Java double-precision floating-point representation, which is based on the IEEE-754 standard
final
maximumPreciseValue → double: The maximum precise value representable in a double. Since IEE754 double-precision numbers allow 53 bits of mantissa, the value is equal to 2^53 - 1. This provides almost 16 decimal digits of precision.
final

Static Methods

mostPrecise(PrecisionModel pm1, PrecisionModel pm2) → PrecisionModel: Determines which of two {@link PrecisionModel}s is the most precise (allows the greatest number of significant digits).