|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
ObjectCodeList<SequenceType>
SequenceType
@UML(identifier="CV_SequenceType", specification=ISO_19123) public class SequenceType
Specifies the order in which attribute value records are assigned to grid points. There are several sequencing rules based on incrementing - or decrementing - grid coordinate values in a simple fashion. More complex space filling curves can also be used. Space filling curves are generated by progressively subdividing a space in a regular way and connecting the elements resulting from each subdivision according to some rule. They can be used to generate a grid, but they can also be used to assign an ordering to the grid points or grid cells in a separately defined grid. They lend themselves more readily than simple incrementing methods to sequencing in grids that have irregular shapes or cells of variable size.
In every case, ordering of the grid cells starts by incrementing coordinates along one grid axis. At some point in the process, it begins to increment coordinates along a second grid axis, then a third, and so on until it has progressed in the direction of each of the grid axes. The attribute scan direction provides a list of signed axis names that identifies the order in which scanning takes place. The list may include an additional element to support interleaving of feature attribute values.
Ordering is continuous if consecutive pairs of grid cells in the sequence are maximally connected. It is semicontinuous if consecutive pairs of grid cells are connected, but less than maximally connected, and discontinuous if consecutive pairs of cells are not connected.
Example: In the two dimensional case, a cell is connected to the 8 cells with which it shares at least one corner. It is maximally connected to the 4 cells with which it shares an edge and two corners. In the three dimensional case, a cell is maximally connected to those cells with which it shares a face.
Field Summary | |
---|---|
static SequenceType |
BOUSTROPHEDONIC
A variant of linear scanning, in which the direction of the scan is reversed on alternate grid lines. |
static SequenceType |
CANTOR_DIAGONAL
Cantor-diagonal scanning, also called zigzag scanning, orders the grid points in alternating directions along parallel diagonals of the grid. |
static SequenceType |
HILBERT
Ordering based on a space-filling curve generated by progressively subdividing a space into quadrants. |
static SequenceType |
LINEAR
Feature attribute value records are assigned to consecutive grid points along a single grid line parallel to the first grid axis listed in scan direction. |
static SequenceType |
MORTON
Ordering based on a space-filling curve generated by progressively subdividing a space into quadrants and ordering the quadrants in a Z pattern. |
static SequenceType |
SPIRAL
Spiral scanning can begin either at the centre of the grid (outward spiral), or at a corner (inward spiral). |
Method Summary | |
---|---|
CodeList[] |
family()
Returns the list of enumerations of the same kind than this enum. |
static SequenceType |
valueOf(String code)
Returns the SequenceType that matches the given string, or returns a new one if none match it. |
static SequenceType[] |
values()
Returns the list of SequenceType s. |
Methods inherited from class CodeList |
---|
compareTo, name, ordinal, readResolve, toString |
Methods inherited from class Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
---|
@UML(identifier="Linear scanning", obligation=CONDITIONAL, specification=ISO_19123) public static final SequenceType LINEAR
@UML(identifier="Boustrophedonic scanning", obligation=CONDITIONAL, specification=ISO_19123) public static final SequenceType BOUSTROPHEDONIC
NOTE: Boustrophedonic scanning is also known as byte-offset scanning.
@UML(identifier="Cantor-diagonal scanning", obligation=CONDITIONAL, specification=ISO_19123) public static final SequenceType CANTOR_DIAGONAL
@UML(identifier="Spiral scanning", obligation=CONDITIONAL, specification=ISO_19123) public static final SequenceType SPIRAL
@UML(identifier="Morton order", obligation=CONDITIONAL, specification=ISO_19123) public static final SequenceType MORTON
NOTE: Because of the shape of the curve formed by the initial ordering of quadrants, Morton ordering is also known as Z ordering.
A grid generated with the Morton ordering technique will be square and its size in each direction will be a multiple of a power of 2. However, the bit interleaving technique for generating an index can be used to order the grid points in any grid, including grids that are irregular in shape or have grid cells of different sizes.
@UML(identifier="Hilbert order", obligation=CONDITIONAL, specification=ISO_19123) public static final SequenceType HILBERT
NOTE: Because of the shape of the curve formed by the initial ordering of quadrants, Hilbert ordering is also known as pi ordering.
Method Detail |
---|
public static SequenceType[] values()
SequenceType
s.
public CodeList[] family()
family
in class CodeList<SequenceType>
public static SequenceType valueOf(String code)
|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |