Projection system

1. A projection system that projects an image based on a measurement of an object including a marker, the projection system comprising:

a visible light projector that projects an image with visible light;

an invisible light projector that projects an invisible light image onto the object with invisible light;

an imaging device that captures the invisible light image projected from the invisible light projector; and

a controller that obtains information regarding reflected invisible light from the object while obtaining three-dimensional measurements of the object to control the image, based on a capture image captured with the imaging device, wherein

the invisible light image includes a bright region having a predetermined invisible light amount and a dark region having an invisible light amount less than the invisible light amount of the bright region,

the invisible light projector emits invisible light to cause the invisible light amount of the dark region in the invisible light image to be more than or equal to a predetermined offset value, the predetermined offset value thus providing the invisible light amount to the dark region, and

the predetermined offset value is set to provide the invisible light amount to the dark region such that the marker receives the invisible light amount at the dark region to result in the amount of the invisible light reflected by the marker at the dark region being larger than the amount of the invisible light reflected by remaining portions of the object other than the marker at the bright region.

2. The projection system according to claim 1 , wherein

the information regarding the reflected invisible light from the object includes a two-dimensional position of the marker.

3. The projection system according to claim 1 , wherein the marker retroreflects the invisible light.

4. The projection system according to claim 1 , further comprising a background member disposed behind the object in a direction in which the invisible light projector emits the invisible light.

5. The projection system according to claim 4 , wherein the controller obtains information regarding invisible light reflected from the object other than the background member.

6. The projection system according to claim 4 , wherein the background member reflects invisible light incident thereon with a polarization state of the invisible light being preserved.

7. The projection system according to claim 6 , wherein

the invisible light projector emits the invisible light having a predetermined polarization state, and

a polarizer is provided to cut off a component having the predetermined polarization state out of invisible light incident on the imaging device.

8. The projection system according to claim 6 , wherein the background member prevents invisible light incident thereon from being diffusely reflected.

9. The projection system according to claim 1 , wherein the invisible light image includes a measurement pattern in accordance with a spatial coding scheme.

10. The projection system according to claim 1 , wherein

the controller generates a depth image based on a plurality of frames of capture image for the invisible light image,

the controller detects 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, and

the controller corrects 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.