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This table stores coordinates and indexes for cells in the MField table.
It allows one to translate between the Peano-HIlbert index (phkey) of a cell and its discrete cartesian coordinates (ix,iy,iz).
NOTE the (ix,iy,iz) coordinates have values in [-1,256], not in [0,255]!
The motivation for this is that it makes it somewhat easier to deal with periodic boundary conditions when
querying for the neighbours of a cell identified by its phkey:
select s2.phkey
from mfield..spatial s1
, mfield..spatial s2
where s1.phkey=123456
and s1.ix between 0 and 255
and s1.iy between 0 and 255
and s1.iz between 0 and 255
and s2.ix between s1.ix-1 and s1.ix+1
and s2.iy between s1.iy-1 and s1.iy+1
and s2.iz between s1.iz-1 and s1.iz+1
| column | type | UCD | unit | description |
|---|
| ix |
integer |
pos.cart.x |
|
The discrete x coordinate of the cell. Values between -1 and 256.
|
| iy |
integer |
pos.cart.y |
|
The discrete y coordinate of the cell. Values between -1 and 256.
|
| iz |
integer |
pos.cart.z |
|
The discrete z coordinate of the cell. Values between -1 and 256.
|
| phkey |
integer |
|
|
The Peano-Hilbert index of the cell. |
| zindex |
integer |
time |
|
The bit-interleaving index of the cell. |
|
