Spatial Transforms

A SpatialTransform stores a registration between reference_fixed and reference_moving. It maps coordinates in the fixed resource to coordinates in the moving resource, in millimetres.

• matrix holds a 4×4 affine as 16 row-major values. For deformable registrations, path_nii_warp points to a displacement field on the fixed grid, applied before the matrix.
• parent_identifier is the fixed resource; derived_from lists both resources.
• generation_method, generation_version and generation_parameters record how the registration was produced. Updates keep the resource’s previous versions.

For slides, transforms use the catalog’s HistoScan.resolution (µm per pixel, [x, y]). Set it from image metadata before storing transforms and keep it unchanged while those transforms refer to it.

See vxreg for coordinate conventions, tool conversions, and examples of writing, chaining and applying transforms.