Internal BLOB-TinyPoint format [since version 5.0]

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TinyPoint is an alternative BLOB format specifically optimized to store Point-Geometries [POINT, POINT Z, POINT M or POINT ZM] consuming a very low storage amount.

The classic BLOB-GEOMETRY encoding always includes an explicit definition of the BBOX requiring 4 double values and consuming 32 bytes.
But on the very specific case of POINT explicitly defining a BBOX is kind of an overkill and is not strictly required.
The new BLOB-TinyPoint encoding just suppresses the BBOX definition, thus requiring a significantly reduced storage amount accordingly to the following table:

GEOMETRY Class BLOB-GEOMETRY
size (in bytes) BLOB-TinyPoint
size (in byes)

POINT 60 24

POINT Z 68 32

POINT M 68 32

POINT ZM 76 40

GEOMETRY Class	BLOB-GEOMETRY size (in bytes)	BLOB-TinyPoint size (in byes)
POINT	60	24
POINT Z	68	32
POINT M	68	32
POINT ZM	76	40

Important notice: developers intending to develop their own codecs supporting the BLOB-TinyPoint encoding could probably find useful using the tinypoint-sample.sqlite DB as a practical implementation reference.

BLOB-TinyPoint format specification

Byte Offset	Content	Notes
0	START [hex 00]	a TinyPoint encoded BLOB value must always start with a 0x00 byte
1	ENDIAN [hex 80 or hex 81]	if this TinyPoint is BIG_ENDIAN ordered must contain a 0x80 byte value otherwise, if this TinyPoint is LITTLE_ENDIAN ordered must contain a 0x81 byte value Any other value [neither 0x80 nor 0x81], means that this BLOB cannot be a valid TinyPoint
2 - 5	SRID	a 32-bits integer value [little- big-endian ordered, accordingly with the precedent one] corresponding to the SRID for this TinyPoint
6	TINYPOINT TYPE	0x01 = TINYPOINT_XY 0x02 = TINYPOINT XYZ 0x03 = TINYPOINT_XYM 0x04 = TINYPOINT_XYZM All following bytes are interpreted accordingly to this one Type declaration; any other value in this position causes the current one to be considered as an invalid TinyPoint.
7 - ...	Point Type specific	length and content depends on Point Type [POINT, POINT Z, POINT M or POINT ZM]
LAST	END [hex FE]	a TinyPoint encoded BLOB value must always end with a 0xFE byte

The preceding one is the general format that SpatiaLite uses for internal representations of any BLOB encoded TinyPoint.
Specific formats for the various classes of POINT-GEOMETRY are as follows:

SFS GEOMETRY Class

TinyPoint Type

Format
Byte Offset	Content	Notes

POINT

TINYPOINT_XY

0 - 7	X coordinate	a double value corresponding to the X coordinate for this POINT
8 - 15	Y coordinate	a double value corresponding to the Y coordinate for this POINT

POINT Z

TINYPOINT_XYZ

0 - 7	X coordinate	a double value corresponding to the X coordinate for this POINT Z
8 - 15	Y coordinate	a double value corresponding to the Y coordinate for this POINT Z
16 - 23	Z coordinate	a double value corresponding to the Z coordinate for this POINT Z

POINT M

TINYPOINT_XYM

0 - 7	X coordinate	a double value corresponding to the X coordinate for this POINT M
8 - 15	Y coordinate	a double value corresponding to the Y coordinate for this POINT M
16 - 23	M coordinate	a double value corresponding to the M coordinate for this POINT M

POINT ZM

TINYPOINT_XYZM

0 - 7	X coordinate	a double value corresponding to the X coordinate for this POINT ZM
8 - 15	Y coordinate	a double value corresponding to the Y coordinate for this POINT ZM
16 - 23	Z coordinate	a double value corresponding to the Z coordinate for this POINT ZM
24 - 31	M coordinate	a double value corresponding to the M coordinate for this POINT ZM

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