Method and apparatus for calculating a distance between an optical apparatus and an object
First Claim
1. A method of extracting distance information, the method comprising:
- projecting a plurality of different lights onto an object;
modulating, by a light modulator having a gain, reflected lights reflected from the object into modulated images;
detecting, by a photodetector, the modulated images and obtaining from the modulated images a plurality of intensity images respectively corresponding to the plurality of different lights;
obtaining a phase delay of each of the reflected lights from the plurality of intensity images; and
calculating a distance to the object from the obtained phase delay,wherein the obtaining of the phase delay comprises referring to a lookup table that stores information obtained by measuring the waveforms of the plurality of different lights and the gain of the light modulator,wherein the lookup table associates the phase delay, the waveforms of the lights projected onto the object, and the gain of the light modulator with each other.
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Abstract
A method and apparatus for determining a distance between an optical apparatus and an object by considering a measured nonlinear waveform, as opposed to a mathematically ideal waveform. The method and apparatus may accurately calculate distance information without being affected by a type of waveform projected onto the object and may not require an expensive light source or a light modulator for generating a light with little distortion and nonlinearity. Further, since the method may be able to use a general light source, a general light modulator, and a general optical apparatus, additional costs do not arise. Furthermore, a lookup table, in which previously calculated distance information is stored, may be used, and thus the amount of computation required to be performed to calculate the distance is small, thereby allowing for quick calculation of the distance information in real time.
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Citations
39 Claims
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1. A method of extracting distance information, the method comprising:
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projecting a plurality of different lights onto an object; modulating, by a light modulator having a gain, reflected lights reflected from the object into modulated images; detecting, by a photodetector, the modulated images and obtaining from the modulated images a plurality of intensity images respectively corresponding to the plurality of different lights; obtaining a phase delay of each of the reflected lights from the plurality of intensity images; and calculating a distance to the object from the obtained phase delay, wherein the obtaining of the phase delay comprises referring to a lookup table that stores information obtained by measuring the waveforms of the plurality of different lights and the gain of the light modulator, wherein the lookup table associates the phase delay, the waveforms of the lights projected onto the object, and the gain of the light modulator with each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of extracting distance information, the method comprising:
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projecting light having a periodic waveform onto an object; modulating, by a light modulator having a plurality of different gains, a light reflected from the object into modulated images; detecting, by a photodetector, the modulated images to obtain a plurality of intensity images respectively corresponding to the plurality of different gains; obtaining a phase delay of the reflected light by using the plurality of intensity images; and calculating a distance to the object from the obtained phase delay, wherein the obtaining of the phase delay comprises obtaining the phase delay by referring to a lookup table having information obtained by measuring waveforms of the projected light and the plurality of different gains of the light modulator, wherein the lookup table associates the phase delay, the waveforms of the lights projected onto the object, and the gain of the light modulator with each other. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. An optical apparatus that determines a distance between the optical apparatus and an object, the optical apparatus comprising:
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a light source that generates a plurality of different lights and projects the plurality of different lights onto the object, each of the plurality of different lights having a periodic waveform; a light modulator having a gain that modulates reflected lights reflected from the object into modulated images, each of the modulated images having a periodic waveform; a photodetector that detects the modulated images obtained by the light modulator and obtains, from the modulated images, a plurality of intensity images respectively corresponding to the plurality of different lights; and a distance information image processor obtains a phase delay of each of the reflected lights from the plurality of intensity images, and calculates the distance between the optical apparatus and the object by referring to a lookup table that stores information obtained by measuring the waveforms of the plurality of different lights and the gain of the light modulator, wherein the lookup table associates the phase delay, the waveforms of the lights projected onto the object, and the gain of the light modulator with each other. - View Dependent Claims (30, 31, 32, 33, 34)
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35. A method of creating a lookup table for calculating distance information between an optical apparatus and an object, the method comprising:
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measuring waveforms of a plurality of different lights projected onto the object and a gain of a light modulator; obtaining polynomial expressions representing the plurality of different lights and the gain of a light modulator from the measured waveforms and the gain; obtaining polynomial expressions with respect to a plurality of intensity images from the polynomial expressions with respect to the waveforms of the plurality of different lights and the gain of the light modulator; representing each of the polynomial expressions with respect to the plurality of intensity images as a sum of a function of a phase delay and a constant term that is not related to the phase delay; defining a vector function of the phase delay in a three-dimensional (3D) space from a combination of differences between a plurality of functions of the phase delay, and defining a specific vector as a reference vector; defining an intensity image vector in the 3D space as a combination of differences between the polynomial expressions with respect to the plurality of intensity images; determining a relationship between a rotation angle of the intensity image vector from the reference vector and a phase delay corresponding to the rotation angle; and expressing the determined relationship in the form of a table or a function. - View Dependent Claims (37)
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36. A method of creating a lookup table for calculating distance information between an optical apparatus and an object, the method comprising:
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measuring waveforms light projected onto the object and a plurality of different gains of a light modulator; obtaining polynomial expressions representing the light and the plurality of different gains of the light modulator from the measured light and the plurality of different gains; obtaining polynomial expressions with respect to a plurality of intensity images from the polynomial expressions with respect to the light and the plurality of different gains of the light modulator; quantizing each of polynomial expressions with respect to the plurality of intensity images as a sum of a function of a phase delay and a constant term that is not related to the phase delay; defining a vector function of the phase delay in a three-dimensional (3D) space from a combination of differences of a plurality of functions of the phase delay, and defining a specific vector as a reference vector; defining an intensity image vector in the 3D space as a combination of differences between the polynomial expressions with respect to the plurality of intensity images; determining a relationship between a rotation angle of the intensity image vector from the reference vector and a phase delay corresponding to the rotation angle; and expressing the determined relationship in the form of a table or a function. - View Dependent Claims (38)
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39. A non-transitory method of calculating a distance between an optical apparatus and an object, the method comprising:
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projecting light onto the object, the light having a waveform; modulating, by a light modulator of the optical apparatus, the light modulator having a gain, light reflected from the object into modulated images; obtaining, from the modulated images, an intensity image corresponding to the light projected onto the object; obtaining, from the intensity image, a phase delay of the light reflected from the object; and calculating, by a processor of the optical apparatus, the distance between the optical apparatus and the object from the phase delay, the waveform of the light projected onto the object, and the gain of the light modulator, wherein the calculating comprises calculating the distance by referring to a lookup table that associates the phase delay, the waveform of the light projected onto the object, and he gain of the light modulator with each other.
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Specification