3D image acquisition apparatus and method of calculating depth information in the 3D image acquisition apparatus
A 3-dimensional (3D) image acquisition apparatus and a method of calculating depth information in the 3D image acquisition apparatus, the 3D image acquisition apparatus including: an optical modulator for modulating light reflected from a subject by sequentially projected N (N is 3 or a larger natural number) light beams; an image sensor for generating N sub-images by capturing the light modulated by the optical modulator; and a signal processor for calculating depth information regarding a distance to the subject by using the N sub-images.
1. A 3-dimensional (3D) image acquisition apparatus comprising:
an optical modulator which modulates light reflected from a subject by sequentially projected N light beams;
an image sensor which generates N sub-images by capturing the light modulated by the optical modulator; and
a signal processor which calculates depth information corresponding to a distance to the subject by using the N sub-images,
wherein N is a natural number that is greater than or equal to 3, and
wherein the image sensor is exposed during a projecting time of each light beam of the N light beams to capture the modulated light and forms the N sub-images during at least a portion of a remaining time of the projecting time of each light beam of the N light beams.
2. The 3D image acquisition apparatus of claim 1 , wherein the N light beams are discontinuously projected.
3. The 3D image acquisition apparatus of claim 1 , wherein the N projected light beams are different from each other and are emitted by one or more light sources.
4. The 3D image acquisition apparatus of claim 3 , wherein the one or more light sources sequentially project the N light beams with a predetermined time interval.
5. The 3D image acquisition apparatus of claim 1 , wherein an operating time of the optical modulator is synchronized with the projecting time of each light beam of the N light beams.
6. The 3D image acquisition apparatus of claim 5 , wherein the operating time of the optical modulator is shorter than the projecting time.
7. The 3D image acquisition apparatus of claim 5 , wherein an exposure time of the image sensor is synchronized with the operating time of the optical modulator.
8. The 3D image acquisition apparatus of claim 1 , wherein all pixels of the image sensor are exposed to the modulated light during the projecting time of each light beam of the N light beams.
9. The 3D image acquisition apparatus of claim 1 , wherein the N light beams are periodic waves having a same period and at least one light beam from among the N light beams comprises a different intensity and a different phase from the other N light beams.
10. The 3D image acquisition apparatus of claim 9 , wherein the optical modulator modulates the reflected light with the same modulation signal.
11. The 3D image acquisition apparatus of claim 1 , wherein the N light beams have the same periodic waves.
12. The 3D image acquisition apparatus of claim 1 , wherein the optical modulator modulates the reflected light with different modulation signals.
13. The 3D image acquisition apparatus of claim 1 , wherein a phase difference between any two light beams projected at adjacent times from among the N light beams is a value obtained by dividing 360° by N.
14. The 3D image acquisition apparatus of claim 1 , wherein the reflected light includes N reflection light beams obtained by reflecting the N light beams from the subject.
15. The 3D image acquisition apparatus of claim 1 , wherein the N sub-images generated by the image sensor to sequentially one-to-one match the N reflection light beams.
16. The 3D image acquisition apparatus of claim 1 , wherein, if the N sub-images do not one-to-one match the N reflection light beams, the signal processor converts the N sub-images on a line by line basis and sequentially one-to-one matches the N line-based sub-images with the N reflection light beams.
17. The 3D image acquisition apparatus of claim 1 , wherein the signal processor generates a first average image by averaging the N sub-images multiplied by first weighting factors, generates a second average image by averaging the N sub-images multiplied by second weighting factors, and calculates the depth information from the first average image and the second average image.
18. The 3D image acquisition apparatus of claim 17 , wherein the depth information is calculated from an arctangent value of a ratio of the first average image to the second average image.
19. A method of calculating depth information, the method comprising:
modulating light reflected from a subject by sequentially projecting N light beams;
generating N sub-images by capturing the modulated light; and
calculating depth information regarding a distance to the subject by using the N sub-images,
wherein N is a natural number that is greater than or equal to 3, and
wherein an image sensor is exposed during a projecting time of each light beam of the N light beams to capture the modulated light and form the N sub-images during at least a portion of a remaining time of the projecting time of each light beam of the N light beams.
20. The method of claim 19 , wherein the N light beams are discontinuously projected.
21. The method of claim 19 , wherein the N projected light beams are different from each other and are emitted by one or more light sources.
22. The method of claim 21 , wherein the N light beams are sequentially projected with a predetermined time interval.
23. The method of claim 19 , wherein an operating time of an optical modulator for modulating the light is synchronized with the projecting time of each light beam of the N light beams.
24. The method of claim 23 , wherein the operating time of the optical modulator is shorter than the projecting time.
25. The method of claim 23 , wherein an exposure time of the image sensor which captures the light is synchronized with the operating time of the optical modulator.
26. The method of claim 25 , wherein all pixels of the image sensor are exposed to the modulated light during the projecting time of each light beam of the N light beams.
27. The method of claim 19 , wherein the N light beams are periodic waves having a same period and at least one light beam from among the N light beams comprises a different intensity and a different phase from the other N light beams, and the reflected light is modulated with the same modulation signal.
28. The method of claim 19 , wherein the N light beams have the same periodic waves, and the reflected light is modulated with different modulation signals.
29. The method of claim 19 , wherein a phase difference between any two light beams projected at adjacent times from among the N light beams is a value obtained by dividing 360° by N.
30. The method of claim 19 , wherein the generated N sub-images sequentially one-to-one match the N reflection light beams.
31. The method of claim 19 , further comprising, if the N sub-images do not one-to-one match the N reflection light beams, converting the N sub-images on a line by line basis and sequentially one-to-one matching the N line-based sub-images with the N reflection light beams.
32. The method of claim 19 , wherein a first average image is generated by averaging the N sub-images multiplied by first weighting factors, a second average image is generated by averaging the N sub-images multiplied by second weighting factors, and the depth information is calculated from the first average image and the second average image.
33. The method of claim 32 , wherein the depth information is calculated from an arctangent value of a ratio of the first average image to the second average image.