voxcity.importer.rhino_obj

Public entry point: add buildings from an OBJ file to a VoxCity model.

Functions

add_buildings_from_obj(voxcity, obj_path, ...[, ...])

Voxelize buildings from an OBJ file and stamp them into a VoxCity model.

Module Contents

voxcity.importer.rhino_obj.add_buildings_from_obj(voxcity, obj_path, 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', roles=None, backend='trimesh', z_up=True, swap_yz=False, overwrite=True, auto_window=True, window_keywords=None, window_value=-16, gridvis=False)[source]

Voxelize buildings from an OBJ file and stamp them into a VoxCity model.

Loads geometry groups from obj_path, selects the groups whose resolved role is "building", places them into the VoxCity domain using an anchor lon/lat + elevation (plus optional rotation/translation/unit scaling), voxelizes each building group, and stamps the resulting cells into a copy of voxcity. The input voxcity is never mutated; this function always returns a new object. See docs/rhino_obj_import.md for the Rhino export guide and conventions.

Parameters:

  • voxcity – source VoxCity object. Read for its grid geometry (extras['rectangle_vertices']), voxel shape, DEM, and existing building grids; never mutated. A deep copy is made internally and returned (with buildings stamped in), or returned unmodified (still a deep copy) if no in-domain geometry is found.

  • obj_path – path to the OBJ file to import. Must exist on disk; checked before any other validation.

  • anchor_lonlat – (lon, lat) pair giving the geographic position that anchor_model_point is placed at. Must have exactly 2 elements.

  • anchor_elevation – elevation (metres) of anchor_model_point in the real world. Combined with the VoxCity DEM minimum to fix the vertical (Z) placement of the model.

  • anchor_model_point – (x, y, z) point in OBJ model coordinates (in units, pre-scale) that is pinned to anchor_lonlat / anchor_elevation. Defaults to the model origin (0.0, 0.0, 0.0).

  • rotation – rotation in degrees applied to the model in the horizontal (east/north) plane before placement. Positive values rotate the model counter-clockwise; e.g. at rotation=90, model +X ends up pointing north. Defaults to 0.0 (no rotation).

  • move – (east, north, up) offset in metres applied after anchoring, e.g. for fine-tuning placement without changing the anchor. Defaults to (0.0, 0.0, 0.0) (no offset).

  • units – model length unit, used to scale OBJ coordinates to metres. One of "m", "cm", "mm", "ft", "in" (case-insensitive). Defaults to "m".

  • roles – optional {group_name: role} mapping overriding the auto-detected role of a group. Recognized roles: "building" (voxelized solid as -3), "window" (surface-voxelized and stamped as glass -16 on the building facade it touches), and "skip" (excluded). Matching is exact-string only. Groups absent from this mapping are auto-classified (see auto_window).

  • backend – voxelization backend. "trimesh" (default) uses voxelize_mesh() (column z-ray casting). "meshlib" uses the optional voxelize_mesh_meshlib() SDF backend, which requires the optional meshlib package to be installed (see Raises below); this backend is best-effort and not empirically verified against a real MeshLib install (see that function’s docstring for details).

  • z_up – whether the OBJ’s vertical axis is already Z-up (Rhino’s convention), the default (True). When False, the loaded mesh is treated as Y-up and axes 1/2 (Y/Z) are swapped before placement, equivalent to setting swap_yz=True.

  • swap_yz – if True, force an explicit Y/Z axis swap on the loaded geometry regardless of z_up. Defaults to False. The effective swap applied is swap_yz or (not z_up).

  • overwrite – if True (default), newly stamped building voxels overwrite any existing non-empty voxel at that cell (and the collision is counted/logged). If False, only cells that are currently empty are stamped; already-occupied cells are left untouched.

  • auto_window – if True (default), groups whose name or assigned OBJ material name contains a window keyword (see window_keywords) are auto-classified as "window". An explicit roles entry always overrides this.

  • window_keywords – optional iterable of case-insensitive substrings used for window auto-detection. None (default) uses ("window", "glass", "glazing").

  • window_value – voxel code written for window cells. Defaults to -16 (the standard glass code).

  • gridvis – if True, after stamping, display a quick-look 2D visualization of the post-import building height grid. Purely a debugging aid; failures in the visualization step (including a missing/broken plotting backend) are swallowed silently. Defaults to False.

Returns:

A new VoxCity object with the imported buildings stamped in (or an unmodified deep copy of voxcity if no building-role geometry was found, or none of it voxelized to cells inside the domain). The voxcity argument passed in is never mutated.

Raises:

  • FileNotFoundError – if obj_path does not exist.

  • ValueError – if units is not one of the recognized unit strings, if backend is not "trimesh" or "meshlib", or if anchor_lonlat does not have exactly 2 elements.

  • ImportError – if backend="meshlib" is requested but the optional meshlib package is not installed.