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Voxelized Grids in DIRSIG4

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Another feature coming in DIRSIG 4.0.6 is support for regular voxelized grids. The advantage of these structures is that they allow for extremely fast intersections of regularly spaced boxes. The backend code for implementing these grids is also used by DIRSIG to implement support for the QUIC concentration map outputs.

In the ODB file:
REGULAR_GRID {
    INSERT_POINT = 0,0,0
    DELTA_X = 20
    DELTA_Y = 10
    DELTA_Z = 25
    GRID_FILENAME = niek.grid
}

The INSERT_POINT indicates a grid extent, the point with the smallest x,y,z coordinate values. DELTA_X/Y/Z indicates the size, in meters, of each voxel. The GRID_FILENAME indicates where the voxel data is stored. Note that the .grid extension is not required.

The contents of the .grid file are as follows:
10      10      10
9       9       0       13      230     0
9       8       0       13      230     0
9       7       0       13      230     0

The first line indicates the number of boxes in the x, y, and z direction. For each line following, the first three values indicate voxel indices (the voxel at the INSERT_POINT is voxel 0,0,0). The fourth value is the material id for this voxel. The fifth value is a temperature, in Kelvin. The sixth value is a concentration, in ppm, which can be used for gases. Voxels left unspecified will be treated as null hits.

The regular grid functionality in DIRSIG is still experimental; the syntax for specifying such a grid is subject to change. At this time, instancing is not yet supported for grid. Furthermore, all grids are currently axis-aligned.

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July 23, 2015 4:13 PM
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