org.apache.lucene.spatial.util

Class GeoEncodingUtils

java.lang.Object

org.apache.lucene.spatial.util.GeoEncodingUtils

public final class GeoEncodingUtils
extends Object

Basic reusable geopoint encoding methods

WARNING: This API is experimental and might change in incompatible ways in the next release.

Field Summary

Fields

Modifier and Type	Field and Description
static short	BITS number of bits used for quantizing latitude and longitude values
static int	BUF_SIZE_LONG The maximum term length (used for byte[] buffer size) for encoding geoEncoded values.
static double	TOLERANCE rounding error for quantized latitude and longitude values

Method Summary

Modifier and Type	Method and Description
static double	compare(double v1, double v2) Compare two position values within a TOLERANCE factor
protected static long	fromBytes(byte b1, byte b2, byte b3, byte b4, byte b5, byte b6, byte b7, byte b8) Converts 8 bytes to a long value
static void	geoCodedToPrefixCoded(long hash, int shift, BytesRefBuilder bytes) Convert a geocoded morton long into a prefix coded geo term
static String	geoTermToString(long term) Converts a long value into a bit string (useful for debugging)
static int	getPrefixCodedShift(BytesRef val) Get the prefix coded geo term shift value
static Long	mortonHash(double lat, double lon) encode latitude, longitude geopoint values using morton encoding method https://en.wikipedia.org/wiki/Z-order_curve
static double	mortonUnhashLat(long hash) decode latitude value from morton encoded geo point
static double	mortonUnhashLon(long hash) decode longitude value from morton encoded geo point
static long	prefixCodedToGeoCoded(BytesRef val) Convert a prefix coded geo term back into the geocoded morton long

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BITS

public static final short BITS

number of bits used for quantizing latitude and longitude values

See Also:

Constant Field Values

BUF_SIZE_LONG

public static final int BUF_SIZE_LONG

The maximum term length (used for byte[] buffer size) for encoding geoEncoded values.

See Also:

geoCodedToPrefixCodedBytes(long, int, BytesRefBuilder), Constant Field Values

TOLERANCE

public static final double TOLERANCE

rounding error for quantized latitude and longitude values

See Also:

Constant Field Values

Method Detail

mortonHash

public static final Long mortonHash(double lat,
                                    double lon)

encode latitude, longitude geopoint values using morton encoding method https://en.wikipedia.org/wiki/Z-order_curve

mortonUnhashLon

public static final double mortonUnhashLon(long hash)

decode longitude value from morton encoded geo point

mortonUnhashLat

public static final double mortonUnhashLat(long hash)

decode latitude value from morton encoded geo point

compare

public static double compare(double v1,
                             double v2)

Compare two position values within a TOLERANCE factor

geoCodedToPrefixCoded

public static void geoCodedToPrefixCoded(long hash,
                                         int shift,
                                         BytesRefBuilder bytes)

Convert a geocoded morton long into a prefix coded geo term

prefixCodedToGeoCoded

public static long prefixCodedToGeoCoded(BytesRef val)

Convert a prefix coded geo term back into the geocoded morton long

getPrefixCodedShift

public static int getPrefixCodedShift(BytesRef val)

Get the prefix coded geo term shift value

fromBytes

protected static long fromBytes(byte b1,
                                byte b2,
                                byte b3,
                                byte b4,
                                byte b5,
                                byte b6,
                                byte b7,
                                byte b8)

Converts 8 bytes to a long value

geoTermToString

public static String geoTermToString(long term)

Converts a long value into a bit string (useful for debugging)