The conditions depend on the camera and detection method you are using, but you'll likely be using the similar formulas for detection. Therefore last years worksheet is still useful. You'll need to determine the necessary pixels to detect corn burors (last year it was 4 pixels for a 5 foot human) and the resolution of your camera (this is in the detailed background).
Also, if you need help with understanding the camera footprint worksheet, look at the 2012/2013 detailed background (last years challenge). The formulas used in the worksheet are explained and show how you can edit them in order to detect larger or smaller pixel densities.