Question

My homework is to write a very simple application (Java or C#, I know both), which can detect water level of a glass of water / coke in a picture (it have to draw a line there). I don’t even know how to start it. I have googled all day, but have found no useful results. Are there any good algorithms, which can detect the level of the liquid?

The photo is taken from the side, like this:

(it’s also good if it detects both lines). So could you help me out with how to start? Use egde detection (are there any good basic algorythms?), or other method?

It would be best would be if it detected water, coke, and every liqued etc….

Answer 1

You are going to have to do some edge detection and then once you have the edges, try and find the level within the glass. You could use a toolkit like Aforge.NET. Then code to detect the edges is pretty simple, for example:

Bitmap b = new Bitmap(Image.FromFile(@"C:\Temp\water.jpg"));
// create filter
Edges filter = new Edges();
// apply the filter
filter.ApplyInPlace(b);

pictureBox1.Image = b;

Yields an image like this:

Now it should be a little bit easier to find the point of water in the glass. Since all of the background noise has been eliminated, you can focus on determining which edge you should key off of.