Update documentation

README.md

@@ -58,3 +58,11 @@ Simply wrap the `Register` in a ROS node, subscribing to pose updates and publis
   - `source venv/bin/activate` (Linux/Mac) or `venv\Scripts\activate` (Windows)
 - Install package with dev and test dependencies
   - `pip install -e '.[dev,test]'`
+
+# Implementation Details
+
+- Transforms are stored as a tree starting from the world frame (provided at `Registry` initialization).
+- To optimize run-time performance, the paths between all pairs of frames are eagerly precomputed and stored when a frame is added.
+  - Therefore, the runtime complexity on request is proportional to the shortest path, instead of all frames in the case of a full graph search.
+- Transitive transforms themselves are only computed on-demand because an intermediate transform can change.
+  - This is preferred because poses often change more often than they are requested.

frame_transforms/transforms.py

@@ -80,7 +80,7 @@ def __matmul__(self, other: TransformTarget_t) -> TransformTarget_t:
         or a 4x4 homogeneous transformation matrix.
         """
         if isinstance(other, Transform):
-            # Correct transformation composition: rotate other's translation, then add this translation
+            # Rotate other's translation, then add this translation
             new_translation = self._translation + self._rotation.apply(
                 other.translation
             )
@@ -95,7 +95,7 @@ def __matmul__(self, other: TransformTarget_t) -> TransformTarget_t:
                 case (4, 4):
                     return self.as_matrix() @ other
                 case (3,):
-                    # Correct vector transformation: rotate first, then translate
+                    # Rotate first, then translate
                     return np.array(self._rotation.apply(other) + self._translation)  # type: ignore[return-value]
                 case _:
                     raise ValueError(
@@ -181,8 +181,8 @@ class Registry(Generic[FrameID_T]):
     """
     Registry of coordinate frames and corresponding transforms.
 
-    Automatically computes transitive tramsforms between frames if possible by
-    maintaining a directed acyclic graph (DAG) of relationships.
+    Automatically computes transitive transforms between frames if possible by
+    maintaining a tree of relationships.
 
     Made for use with 4x4 3D transformation matrices.
     """

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "frame-transforms"
-version = "0.3.0"
+version = "0.3.1"
 readme = "README.md"
 python = "^3.10"