Project help, detecting motion

Hi there, My project initiates when the user walks up to a screen.

I've researched:
Passive Infrared Sensors (Starts when someone nears the sensor)
Force Sensitive Sensors (Starts when someone stands in a specific area (weight))
Photo Electric Sensors (Starts when someone stands in a specific area (breaks the light-beam))

I've been advised to look up the likes of Blob Detection and Gesture Detection but apart from sensors I'm unsure of other options.
Any ideas on initiating the start of media by anything apart from triggering a sensor?

Thanks

The obvious one is ultrasonic,

However, if "advised" means instructor/professor, I suspect you need to follow that line of thinking.

Ray

Ultrasonic may well be quite a poor choice; humans tend to be squishy,and not good reflectors.

Thanks for the ultrasound suggestion!

By 'advise', yes my tutor advised looking elsewhere but still likes the idea of sensors once they work perfectly, so sensors are still in question for me. My friend lent me an object tracking sensor but i'm guessing thats no good? Most likely i'll have to buy the most appropriate sensor instead.

It is hard to beat PIR sensors for cost, simplicity, range and adjustable sensitivity. I don't know about Kinect, but inexpensive Blob Detection cameras like CMUCam rely on the blob color and connectivity for tracking, which seems unlikely to work for a random human.

kinect uses IR structured light.. quite impressive.

Range?

If you use PIR sensors, you'll want to provide some kind of screening so it only sees the area of interest. I have a PIR triggered light next to my front door, it lights up even when someone drives by. If I had the option, I'd mount it higher and point it down.

polymorph:
Range?

If you use PIR sensors, you'll want to provide some kind of screening so it only sees the area of interest. I have a PIR triggered light next to my front door, it lights up even when someone drives by. If I had the option, I'd mount it higher and point it down.

You can add an IR blocking mask to limit the sensing area. Some brands of PIR are even supplied with small shields designed to be installed inside the housing for that purpose.