Doc update

Author: RomanJuranek

README.md

@@ -39,11 +39,39 @@ Alternatively, you can download this repository and install manually.
 import pclines as pcl
 ```
 
-2. Accumulation of observations
-The observations are 2D weighted coordinates enclosed by a known bounding box.
+2. Data and observations
+The observations are 2D weighted coordinates enclosed by a known bounding box. As an example we extract edge points from an image.
 
-*TBD*
+```python
+image = imread("doc/test.png", as_gray=True)
+edges = sobel(image)
+r,c = np.nonzero(edges > 0.5)
+x = np.array([c,r],"i").T
+weights = edges[r,c]
+```
+![](doc/image.png) ![](doc/edges.png)
+
+3. Accumulation in PCLines space
+
+```python
+h,w = image.shape[:2]
+bbox=(0,0,w,h)  #  Bounding box of observations
+d = 1024  # Accumulator resolution
+P = PCLines(bbox, d) # Create new accumulator
+P.insert(x, weights) # Insert observations
+p, w = P.find_peaks(min_dist=10, prominence=1.3, t=0.1) # Find local maxima
+```
+
+![](doc/accumulator.png)
+
+4. Detected lines
+
+```python
+h = P.inverse(p)  # (a,b,c) parameters of lines
+X,Y = utils.line_segments_from_homogeneous(h, bbox)  # Convert to line segments for plotting
+```
 
+![](doc/lines.png)
 
 
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