Package org.apache.sis.geometry

Basic geometric objects (envelopes and direct positions). Every geometry objects are associated with a Coordinate Reference System, which may have an arbitrary number of dimensions. However a few specialized classes restrict the CRS to a fixed number of dimensions only. The table below summarizes the most common objects, and list the Java2D classes that are conceptually equivalent.
Java2D and geometry equivalences
Purpose Any dimension One dimension Two dimensions Java2D equivalence
A point in a multi-dimensional space GeneralDirectPosition DirectPosition1D DirectPosition2D Point2D
A box in a multi-dimensional space GeneralEnvelope Envelope2D Rectangle2D
Java2D dependency
All classes having a name that ends with "2D" are designed for inter-operability with Java2D. All other classes have no dependency to Java2D. This clear separation aims to make easier to use Apache SIS on platforms that do not support Java2D (for example Android) or to avoid loading Java2D classes when only JavaFX is desired.
Envelopes spanning the anti-meridian of a Geographic CRS
The Web Coverage Service (WCS) 1.1 specification uses an extended interpretation of the bounding box definition. In a WCS 1.1 data structure, the lower corner defines the edges region in the directions of decreasing coordinate values in the envelope CRS, while the upper corner defines the edges region in the directions of increasing coordinate values. Those lower and upper corners are usually the algebraic minimum and maximum coordinates respectively, but not always. For example, an envelope crossing the anti-meridian could have a lower corner longitude greater than the upper corner longitude, like the red box below (the green box is the usual case):
Envelope spannning the anti-meridian
In SIS, every envelopes defined in this package support the extended bounding box interpretation: for any dimension, coordinate values such that upper < lower are handled in a special way. This handling is slightly different for two groups of methods:
  • In calculation of envelopes spans and median positions (centers) — handled specially only on axes having the WRAPAROUND range meaning.
  • When checking for containment, intersections or unions — can be handled specially for any axis, in which case the envelope represents an exclusion area instead than an inclusion area.
See Also:

Defined in the sis-referencing module