A projection system (1, 1A, 1B) that projects an image based on a measurement of an object, the projection system (1, 1A, 1B) comprising: a visible light projector configured to project an image with visible light; an invisible light projector configured to project an invisible light image (80, 80A) onto the object with invisible light; an imaging device configured to capture the invisible light image projected from the invisible light projector; a marker configured to reflect the invisible light, and adapted to be fixed to the object, and a controller configured to obtain information regarding reflected invisible light from the object, configured to obtain three-dimensional measurements of the object for a depth image and configured to control the visible image, based on a capture image captured with the imaging device, wherein the invisible light image (80, 80A) includes a bright region having a predetermined light amount and a dark region having a light amount less than the light amount of the bright region, and the invisible light projector is configured to project a set of measurement patterns, superimposed with invisible light having a uniform distribution to cause the light amount of the dark region in the invisible light image to be more than or equal to a predetermined offset value, the controller is configured to generate the depth image based on a plurality of frames of capture image by decoding the bright region and the dark region, the controller is configured to detect in two dimensions the position or contour of the object on each frame of capture image by detecting the pixels having a brightness more than a predetermined threshold, characterized in that the controller is configured to correct the image projected by the visible light projector three-dimensionally each time the depth image is generated, and, within a period corresponding to a plurality of frames until a new depth image is obtained, two-dimensionally on a frame-by-frame basis based on the two dimensional detection, wherein the predetermined offset value is set such that the marker reflects more amount of the invisible light in the capture image than other part of the object. a visible light projector configured to project an image with visible light; an invisible light projector configured to project an invisible light image (80, 80A) onto the object with invisible light; an imaging device configured to capture the invisible light image projected from the invisible light projector; a marker configured to reflect the invisible light, and adapted to be fixed to the object, and a controller configured to obtain information regarding reflected invisible light from the object, configured to obtain three-dimensional measurements of the object for a depth image and configured to control the visible image, based on a capture image captured with the imaging device, wherein the invisible light image (80, 80A) includes a bright region having a predetermined light amount and a dark region having a light amount less than the light amount of the bright region, and the invisible light projector is configured to project a set of measurement patterns, superimposed with invisible light having a uniform distribution to cause the light amount of the dark region in the invisible light image to be more than or equal to a predetermined offset value, the controller is configured to generate the depth image based on a plurality of frames of capture image by decoding the bright region and the dark region, the controller is configured to detect in two dimensions the position or contour of the object on each frame of capture image by detecting the pixels having a brightness more than a predetermined threshold, characterized in that the controller is configured to correct the image projected by the visible light projector three-dimensionally each time the depth image is generated, and, within a period corresponding to a plurality of frames until a new depth image is obtained, two-dimensionally on a frame-by-frame basis based on the two dimensional detection, wherein the predetermined offset value is set such that the marker reflects more amount of the invisible light in the capture image than other part of the object.