Holds classes and routines for calculating Hierarchical Triangular Mesh (HTM) Identifiers of points and cover maps for regions as well as the relevant SQL Server 2005 wrapper UDFs.
Classes
Class | Description | |
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Cover |
Cover provides static (a) methods to generate trixel covermaps of regions
A covermap can be extracted as a list of trixels, or lists of HtmID
(start, end) pairs.
In the latter case, the HtmIDs are always for level 20 trixels.
The trixels in the covermaps are either "inner" or "partial".
Inner trixels are completely contained
in the region. Partial trixels intersect the boundary of the
region. Partial trixels follow the outline(s) of the region.
The "outer" covermap is the union of
"inner" and "partial" covermaps.
Each covermap has an associated "cost," which is currently the number of
(start, end) HtmID range pairs in the outer covermap.
The cost is used in deciding when
to terminate the generation of the covermap
The Cover object uses an internal "machine" that
does all the computing. The machine runs in stages, each successive step
generates a finer
resolution covermap and therefore increases the depth of the partial
trixels in the covermap.
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Hidranges |
Hidranges manages lists of HtmID pairs. It is used mostly
internally by the Cover class. It has public exposure, because
the external test harness not in this namespace uses this class
for verifying the internal workings of the HTM library
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HtmState |
A singleton class housing many internal 'global' variables. Exposed only
for its getVersion method
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Sql | ||
Trixel |
Trixel static methods operate on HtmID's mostly.
operations needed to convert between location and HtmID
several representations of a HtmID, and locations expressed
in Cartesian, J2000 (ra/dec) geographic lat/lon space.
Since functions in the Spherical assembly convert
to and from J2000 or geographic coordinates, only XYZ
is handled by this class
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Structures
Structure | Description | |
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Int64AugPair |
An augmented pair of HtmId values. Besides the low-high pair, it also
includes a flag that indicates whether or not the trixels represented by the
range are inner trixels.
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Int64Pair |
A pair of low-high HtmId values
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Enumerations
Enumeration | Description | |
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Markup |
Markup is a classification of a trixel with respect to the way it intersects a
region.
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