Electronic device and method for adjusting size of three-dimensional object in augmented reality

1. An electronic device, comprising:

an image sensor, configured to capture a plurality of object images of a target object, wherein a first positioning tag, a second positioning tag, and a third positioning tag are disposed on the target object;

a display device;

a processor, configured to perform an augmented-reality program to perform steps of:

recognizing the first positioning tag, the second positioning tag, and the third positioning tag from each object image;

calculating a scaling ratio corresponding to each dimension of a three-dimensional object according to positions of the recognized first positioning tag, the recognized second positioning tag, and the recognized third positioning tag;

performing an image-scaling process on the three-dimensional object according to the scaling ratio corresponding to each dimension of the three-dimensional object and rendering the scaled three-dimensional object; and

overlaying the scaled three-dimensional object on each object image to generate an output image and displaying the output image on the display device,

wherein first three-dimensional coordinates of the first positioning tag are origin coordinates of the scaled three-dimensional object,

wherein the AR program executed by the processor further performs the following steps:

calculating a vertical distance according to the first three-dimensional coordinates of the first positioning tag and second three-dimensional coordinates of the second positioning tag;

calculating a horizontal distance according to the first three-dimensional coordinates of the first positioning tag and third three-dimensional coordinates of the third positioning tag;

dividing height and width of the three-dimensional object with the vertical distance and the horizontal distance to obtain a vertical scaling ratio and a horizontal scaling ratio, respectively,

setting the smaller of the vertical scaling ratio and the horizontal scaling ratio as a depth scaling ratio; and

performing the image-scaling process on length, width, and depth of the three-dimensional object to render the scaled three-dimensional object.

2. The electronic device as claimed in claim 1 , wherein the processor sequentially recognizes the first positioning tag, the second positioning tag, and the third positioning tag in a first time period, a second time period, and a third time period, respectively,

wherein the third time period is later than the second time period, and the second time period is later than the first time period.

3. A method for adjusting size of a three-dimensional object in augmented reality (AR), for use in an electronic device, wherein the electronic device comprises an image sensor and a display device, the method comprising:

utilizing the image sensor to capture a plurality of object images of a target object, wherein a first positioning tag, a second positioning tag, and a third positioning tag are disposed on the target object;

recognizing the first positioning tag, the second positioning tag, and the third positioning tag from each object image;

calculating a scaling ratio corresponding to each dimension of a three-dimensional object according to positions of the recognized first positioning tag, the recognized second positioning tag, and the recognized third positioning tag;

performing an image-scaling process on the three-dimensional object according to the scaling ratio in respect to each dimension of the three-dimensional object and rendering the scaled three-dimensional object; and

overlaying the scaled three-dimensional object on each object image to generate an output image and displaying the output image on the display device,

wherein first three-dimensional coordinates of the first positioning tag are origin coordinates of the scaled three-dimensional object,

wherein the step of performing an image-scaling process on the three-dimensional object according to the scaling ratio in respect to each dimension of the three-dimensional object and rendering the scaled three-dimensional object comprises:

calculating a vertical distance according to the first three-dimensional coordinates of the first positioning tag and second three-dimensional coordinates of the second positioning tag;

calculating a horizontal distance according to the first three-dimensional coordinates of the first positioning tag and third three-dimensional coordinates of the third positioning tag;

dividing height and width of the three-dimensional object with the vertical distance and the horizontal distance to obtain a vertical scaling ratio and a horizontal scaling ratio, respectively;

setting the smaller of the vertical scaling ratio and the horizontal scaling ratio as a depth scaling ratio; and

performing the image-scaling process on the length, width, and depth of the three-dimensional object to render the scaled three-dimensional object.

4. The method as claimed in claim 3 , further comprising:

sequentially recognizing the first positioning tag, the second positioning tag, and the third positioning tag in a first time period, a second time period, and a third time period, respectively,

wherein the third time period is later than the second time period, and the second time period is later than the first time period.