If there are N images, the cylinder is made of N panels each with N facets. Strictly, it is a regular polygonal prism.
More facets makes for a smoother result but a larger file and increased rendering time.
The level 0 cylinder extends from Y1 metres to Y2 metres in height. The radius is determined from the image sizes. Level - 0 corresponds to a set of photographs shot with the camera horizontal. A digital still camera will do nicely. With a digital video camera, you can just swing the camera in a circle and figure it out later.