1. An interactive projection system comprising: a projection device with a projection lens, and the projection lens used for projecting a plurality of the calibrating patterns formed by visible light onto a screen individually, wherein the areas of the calibrating patterns are not all equal; an image capture device comprising an image sensor connected to the projection device and a filter fixed on the image sensor, wherein the image sensor has an optical axis passing through the filter and is used to capture the images of the calibrating patterns through the filter; and a distance between the optical axis and the calibrating pattern with a large area is larger than a distance between the optical axis and the calibrating pattern with a small area.