Migrating from Open3D

Open3D's point-cloud and reconstruction API maps closely onto ordito.points, ordito.registration, ordito.reconstruction, and ordito.voxels — the main structural difference is that Open3D's PointCloud / TriangleMesh are mutable objects with in-place filters, where ordito functions take arrays and return new arrays.

import open3d as o3d  # before
import ordito as od  # after

Point clouds

Open3D	ordito
`pcd.estimate_normals()`	`points.estimate_normals(points, neighbor_idx)` (neighbourhood built explicitly via `neighbors.query_nearest`; normals oriented away from the cloud's centroid, where Open3D leaves the sign arbitrary until an `orient_normals_*` call)
`pcd.remove_radius_outlier(nb_points, radius)`	`points.radius_outlier_mask` (returns a mask of the outliers; keep the rest with `array.flatnonzero` and a gather)
`pcd.remove_statistical_outlier(nb_neighbors, std_ratio)`	`points.statistical_outlier_mask` (also a mask)
`pcd.voxel_down_sample(voxel_size)`	`voxels.voxel_down_sample`
`pcd.farthest_point_down_sample(n)`	`points.farthest_point_sample`
`o3d.geometry.VoxelGrid.create_from_point_cloud`	`voxels.voxelize_points`
`o3d.geometry.VoxelGrid.create_from_triangle_mesh`	`voxels.voxelize_mesh`

Registration

Open3D	ordito
`o3d.pipelines.registration.registration_icp(..., TransformationEstimationPointToPoint())`	`registration.icp`
`o3d.pipelines.registration.registration_icp(..., TransformationEstimationPointToPlane())`	`registration.icp_point_to_plane`
A manual Procrustes / Kabsch fit over known correspondences	`registration.procrustes`

Surface reconstruction and meshes

Open3D	ordito
`TriangleMesh.create_from_point_cloud_poisson`	`reconstruction.screened_poisson`
`TriangleMesh.create_from_point_cloud_ball_pivoting`	`reconstruction.ball_pivoting`
`TriangleMesh.get_volume()`	`measures.volume` / `Trimesh.volume`
`TriangleMesh.is_watertight()`	`validation.is_watertight` / `Trimesh.is_watertight`
`TriangleMesh.simplify_quadric_decimation`	`remesh.quadric_decimate`
`TriangleMesh.filter_smooth_laplacian`	`smoothing.filter_laplacian`
`TriangleMesh.filter_smooth_taubin`	`smoothing.filter_taubin`

Ray casting

Open3D (`o3d.t.geometry.RaycastingScene`)	ordito
`.compute_closest_points()`	`proximity.closest_point_on_mesh`
`.compute_signed_distance()`	`proximity.signed_distance_on_mesh` (same sign convention: negative inside)
`.cast_rays()` (first hit)	`ray.intersects_first` / `ray.intersects_location`
`.count_intersections()` (parity test)	`ray.contains_points`

What's different, not just renamed

No mutable-object filters. Every Open3D TriangleMesh/PointCloud method that returns self after mutating in place (.remove_duplicated_vertices(), .compute_vertex_normals(), ...) is a ordito function returning a new array, e.g. repair.remove_duplicated_vertices.
Legacy vs. tensor API distinction doesn't apply. ordito has one API; there's no separate o3d.t.geometry GPU path to choose — every function already runs on whatever device its input arrays are on.