Any good examples of projects doing vision and image analysis?

Question

I have a need to take an image of a series of glass test tubes, and automatically give an indication of either the level fo liquid in the tubes or the point at which the liquid reaches the bottom of the tubes. The image would probably be gathered by a webcam and processed on a standard PC. I have no restrictions on language or method, but I'll have to learn whatever it is.

I've found these more general questions on Vision on SO;

• learning-about-computer-vision,
• what-is-the-best-library-for-computer-vision-in-c-c,
• open-source-machine-vision-libraries,
• where-do-i-start-learning-about-image-processing-and-object-recognition,

Does anyone know of any similar projects that are well documented that I could review, or other ideas / comments.

Answer 1

If you do it with image analysis, the first thing is to get the best possible image quality. Webcam will probably do, but in addition you'll need some illumination. You want your image's background brightness to be equal everywhere and get rid of shadows, to help segmenting the image correctly. Possibly illuminating the tubes from the back could make sense.

It could be tricky - since your liquids and tubes are clear, the surface of the liquid might not be too well visible. You could also consider using ultrasound-based approach (measure the time of echo from the surface of the liquid).

Edit: one more idea: If the tubes are open from the top, why don't blow air over them, measure the pitch, and calculate the liquid level from that :-)