voxcity.importer.transform

Build the affine that maps OBJ model coordinates to VoxCity voxel indices.

Convention (rotation=0, axis-aligned domain):

model +X -> +v (east / array axis 1) model +Y -> +u (north / array axis 0) model +Z -> +k (up)

Positive rotation (degrees) rotates the model counter-clockwise in the (east, north) plane so that, at rotation=90, model +X points north (+u).

The composed transform (right-to-left, applied to a column vector [x, y, z, 1]):

  M = Toff @ Sv @ T1 @ R @ S @ T0

T0  translate model space so ``anchor_model_point`` becomes the origin.
S   scale model units -> metres (``unit_scale(units)``).
R   rotate the now-metric (x=east, y=north) vector by ``rotation`` degrees,
    then re-express it in the VoxCity domain's own (u, v) axes -- the domain
    itself may be rotated relative to true north (``domain_rotation``).
T1  translate to the anchor's position in domain metres (``u_a, v_a``),
    apply the horizontal/vertical ``move`` offset, and shift the vertical
    datum so the DEM minimum sits at z=0 (matching the voxel grid's ground
    datum).
Sv  scale metres -> voxel indices (divide by ``meshsize``) and add the +1
    vertical offset because the voxelizer seats buildings one voxel above
    the ground voxel (``ground_level = int(dem/voxel_size + 0.5) + 1``).

Functions

grid_geom_from_voxcity(voxcity)	Recover grid geometry from a VoxCity object via its rectangle_vertices.
build_placement_transform(voxcity, anchor_lonlat, ...)	Return a 4x4 affine mapping model coords -> voxel index space (i, j, k).

Module Contents

voxcity.importer.transform.grid_geom_from_voxcity(voxcity)

Recover grid geometry from a VoxCity object via its rectangle_vertices.

voxcity.importer.transform.build_placement_transform(voxcity, anchor_lonlat, anchor_elevation, anchor_model_point=(0.0, 0.0, 0.0), rotation=0.0, move=(0.0, 0.0, 0.0), units='m')

Return a 4x4 affine mapping model coords -> voxel index space (i, j, k).