Circle (#20)

* find circle radius and center

* update readme

.gitignore

@@ -160,4 +160,5 @@ cython_debug/
 #.idea/
 
 output
-lines
+lines
+.vscode

README.md

@@ -1,10 +1,24 @@
 # cnceye
 ![Test](https://github.com/OpenCMM/cnceye/actions/workflows/ci.yml/badge.svg)
 
-cnceye measures the dimensions of a workpiece using the a laser triagulation sensor on a CNC machine.
+cnceye analyzes 3D models from a stl file and find measuring lines and curves.
 
 ![a laser triagulation sensor](https://opencmm.xyz/assets/images/sensor-55b7cf98350f293eba2c2b9d593bdd4f.png)
 
+## Installation
+```bash
+pip install cnceye
+```
+
+## Usage
+
+```python
+from cnceye import Shape
+
+shape = Shape("tests/fixtures/stl/sample.stl")
+lines, arcs = shape.get_lines_and_arcs()
+```
+
 ## Simulation with Blender
 Create test data
 

cnceye/__init__.py

@@ -0,0 +1 @@
+from .shape import Shape # noqa: F401

cnceye/arc.py

@@ -0,0 +1,70 @@
+import numpy as np
+from scipy.optimize import least_squares
+
+
+def get_edges_for_arc(arc_points: np.ndarray, number_of_edges: int):
+    """
+    Returns a list of edges for an arc/circle
+    Edges need to be distributed evenly along the arc
+    """
+    count = len(arc_points)
+    if count < 4:
+        raise ValueError("Not enough points to define arc")
+
+    if number_of_edges < 3:
+        raise ValueError("Not enough edges to define arc")
+
+    interval = count // number_of_edges
+
+    edges = []
+    for i in range(number_of_edges):
+        x, y, z = arc_points[i * interval].tolist()
+        edges.append((round(x, 3), round(y, 3), round(z, 3)))
+
+    return edges
+
+
+def get_arc_info(arc_points: np.ndarray, decimal_places: int = 3):
+    """
+    Get information about arc
+
+    Parameters
+    ----------
+    arc_points : list
+        List of arc coordinates [(x,y,z), (x,y,z)]
+    decimal_places : int
+        Number of decimal places to round to
+
+    Returns
+    -------
+    radius : float
+        Radius of arc
+    center : np.array
+        Center of arc
+    """
+    center_x, center_y, radius = fit_circle(arc_points[:, :2])
+    center = np.array([center_x, center_y, arc_points[0, 2]])
+    center = np.round(center, decimal_places)
+    radius = round(radius, decimal_places)
+    return radius, center
+
+
+def fit_circle(points):
+    x = points[:, 0]
+    y = points[:, 1]
+
+    initial_params = (
+        np.mean(x),
+        np.mean(y),
+        np.std(np.sqrt((x - np.mean(x)) ** 2 + (y - np.mean(y)) ** 2)),
+    )
+
+    result = least_squares(circle_residuals, initial_params, args=(x, y))
+    cx, cy, r = result.x
+
+    return cx, cy, r
+
+
+def circle_residuals(params, x, y):
+    cx, cy, r = params
+    return (x - cx) ** 2 + (y - cy) ** 2 - r**2

cnceye/shape.py

@@ -1,6 +1,7 @@
 import trimesh
 import numpy as np
 from trimesh.graph import face_adjacency
+from .arc import get_arc_info
 
 
 class Shape:
@@ -80,6 +81,27 @@ def group_by_coplanar_facets(self, facet_indices: np.ndarray):
         return coplanar_facets
 
     def get_lines_and_arcs(self, decimal_places: int = 3, arc_threshold: int = 1):
+        """
+        Extract lines and arcs from an STL file \n
+        If the line length is less than 1, it is considered an arc.
+        If the line length for an arc is close to the previous arc length,
+        it is considered part of the previous arc. \n
+        Note: This is not a robust algorithm.
+
+        Parameters
+        ----------
+        decimal_places : int
+            Number of decimal places to round to
+        arc_threshold : int
+            Length threshold to determine if a line is an arc
+
+        Returns
+        -------
+        lines : list
+            List of lines
+        arcs : list
+            List of arcs
+        """
         shapes = self.get_shapes()
         lines = []
         arcs = []
@@ -118,13 +140,6 @@ def get_lines_and_arcs(self, decimal_places: int = 3, arc_threshold: int = 1):
         return lines, arcs
 
     def get_shapes(self):
-        """
-        Extract lines and arcs from an STL file \n
-        If the line length is less than 1, it is considered an arc. \n
-        if the line length for an arc is close to the previous arc length,
-        it is considered part of the previous arc. \n
-        Note: This is not a robust algorithm.
-        """
         visible_facet_indices = self.get_visible_facets()
         group_facets = self.group_by_coplanar_facets(visible_facet_indices)
         adjacency = face_adjacency(self.mesh.faces)
@@ -152,6 +167,26 @@ def get_shapes(self):
 
         return shapes
 
+    def get_arc_info(self, arc_points: np.ndarray, decimal_places: int = 3):
+        """
+        Get information about arc
+
+        Parameters
+        ----------
+        arc_points : list
+            List of arc coordinates [(x,y,z), (x,y,z)]
+        decimal_places : int
+            Number of decimal places to round to
+
+        Returns
+        -------
+        radius : float
+            Radius of arc
+        center : np.array
+            Center of arc
+        """
+        return get_arc_info(arc_points, decimal_places=decimal_places)
+
 
 def round_shape_values(shapes: np.ndarray, decimal_places: int = 3):
     for i in range(len(shapes)):

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "cnceye"
-version = "0.4.3"
+version = "0.5.0"
 description = "CMM python library"
 license = "MIT"
 authors = ["yuichiroaoki <45054071+yuichiroaoki@users.noreply.github.com>"]
@@ -13,6 +13,7 @@ python = ">=3.11,<3.13"
 trimesh = "^4.0.5"
 numpy = "^1.26.2"
 rtree = "^1.1.0"
+scipy = "^1.11.4"
 
 
 [tool.poetry.group.dev.dependencies]

tests/test_arc.py

@@ -0,0 +1,42 @@
+from cnceye import Shape
+from cnceye.arc import (
+    fit_circle,
+    get_arc_info,
+    get_edges_for_arc,
+)
+
+
+def test_fit_circle():
+    shape = Shape("tests/fixtures/stl/sample.stl")
+    lines, arcs = shape.get_lines_and_arcs()
+    for arc_points in arcs[0]:
+        points = arc_points[:, :2]
+        center_x, center_y, radius = fit_circle(points)
+        assert radius > 0.0
+
+
+def test_get_arc_info():
+    shape = Shape("tests/fixtures/stl/sample.stl")
+    lines, arcs = shape.get_lines_and_arcs()
+    for arc_points in arcs[0]:
+        radius, center = get_arc_info(arc_points)
+        assert radius == 9.0 or radius == 5.0
+
+
+def test_get_edges_for_arc():
+    shape = Shape("tests/fixtures/stl/sample.stl")
+    lines, arcs = shape.get_lines_and_arcs()
+    for arc_points in arcs[0]:
+        edges = get_edges_for_arc(arc_points, 3)
+        assert len(edges) == 3
+
+
+def test_get_edges_for_arc_many_edges():
+    shape = Shape("tests/fixtures/stl/sample.stl")
+    lines, arcs = shape.get_lines_and_arcs()
+    for arc_points in arcs[0]:
+        edges = get_edges_for_arc(arc_points, 4)
+        assert len(edges) == 4
+
+        edges = get_edges_for_arc(arc_points, 6)
+        assert len(edges) == 6

tests/test_shape.py

@@ -1,4 +1,4 @@
-from cnceye.shape import Shape
+from cnceye import Shape
 
 
 def test_are_facets_on_same_plane():
@@ -60,3 +60,11 @@ def test_get_lines_and_arcs_with_step_slope():
     assert len(lines[0]) == 4
     assert len(lines[1]) == 4
     assert len(lines[2]) == 4
+
+
+def test_get_arc_info():
+    shape = Shape("tests/fixtures/stl/sample.stl")
+    lines, arcs = shape.get_lines_and_arcs()
+    for arc_points in arcs[0]:
+        radius, center = shape.get_arc_info(arc_points)
+        assert radius == 9.0 or radius == 5.0