Rob Carr Spring 2011 first presentation - go board

1. gobject-detector
Robert Carr
racarr@gnome.org

2. Sorry...
Actually has nothing to do with GObject

3. Go!

4. Go! (Weiqi, Baduk, Awesome)

~4000 year old board
game.

Place black and white
stones on board
intersection.

Probably don't ask me
for details or I will
never stop talking.

5. A Problem...

Common and important to review finished games.

Manual recording is tedious.

Human Memory is limited..

6. Enter gobject-detector

Scans an image, to transcribe a photo of a Go
Board to SGF (Smart Game Format)

7. How does it work?

Well.... first you start
from an image.

8. Edge Detection

The first step is a
Canny Edge
detector, to identify
areas of maximum
gradient in the
image.

9. Hough Transform

A computer vision
method for
obtaining
parameterizations of
lines in images.

10. Board Detection

Once we have a list of
candidate lines we
can find the four
largest, and use
them to compute
our corners and a
center.

11. Perspective transformation

Now that we have our
4 corners we can
order them and then
compute a
perspective
mapping.

12. Now for the grid....

Requires the board to
be oriented
correctly...

13. Image Filtering
 Grain! Some images
have glare and
shadows, difficult to
distinguish from
white and black
stones.
 Fix the colors
some...equalize the
lighting

14. Stone detection

Easy at this point. Just sample in a circle around
each grid point!

15. So wait how does this solve the
problem?

Anrdroid app.

Listens for sound of stone contacting wood and
takes that as a queue to take a new picture of
the board.

iPeter might write me an iPhone app.

16. What else?

This library will not detect the usage of libgobject
in your code

Play online using physical board, with webcam.

Probably need a new name. Go Image
Manipuation Package (GIMP), or Go Toolkit
(GTK?)

Integrated with SGF organizer app.

17. Questions?