This week, I finished the first letter specific feature's analysis -- symmetry for letter m.
I took these steps to extract the feature
Step 1: scan the file, and if the gesture is m, find the bounding box and compute the middle line function y = b
Step 2: pass the b value (from step 1) and the corresponding list of points to find all crossing points, and store them in another list - cross point list. If two adjacent points Point 1 and Point 2 are on different sides of the line y = b, I consider the second point as a crossing point.
Step 3: filter some of the gestures according to the number of crossing points.
Only 1 crossing point: maybe a gesture that was not logged properly
Too many crossing points (e.g. 12 crossing points in Gesture 31 from Subject 10): the subject wrote two m…
Step 4: compute length of segments, and check which is on the left and which is on the right.
Step 5: get the ratio between two segments. Here, I use right_segment_length / left_segment_length, and compute average value for each level
The result shows that there are only significant differences in limited conditions. I think this is a potential feature, but still need adjustment to investigate in more details.