WO2018076663A1

WO2018076663A1 - Method and system for unwrapping panoramic image

Info

Publication number: WO2018076663A1
Application number: PCT/CN2017/084481
Authority: WO
Inventors: 王士博; 沈靖程; 刘亚辉
Original assignee: 深圳市圆周率软件科技有限责任公司
Priority date: 2016-10-31
Filing date: 2017-05-16
Publication date: 2018-05-03
Also published as: CN106991640B; CN106991640A

Abstract

Provided in the present disclosure are a method and a system for unwrapping a panoramic image. The method comprises: dividing equally and longitudinally, by an equal latitudinal difference N-1, a spherical panoramic image into N spherical regions, and respectively projecting the N spherical regions to obtain an unwrapped latitudinal view; dividing equally and latitudinally, by longitudinal difference M-1, the unwrapped latitudinal view into M spherical regions, and respectively projecting the M spherical regions to obtain an unwrapped longitudinal view; uniformly transferring the lower half of the hexagon of the unwrapped longitudinal view to the upper half of the hexagon of the unwrapped longitudinal view and splicing same to obtain a plane panoramic image. In the method and system for unwrapping a panoramic image provided in the present disclosure, the size of the unwrapped two-dimensional image is smaller than the size of the image unwrapped using the popular panoramic image unwrapping method, while guaranteeing that the unwrapped plane images have identical quality, achieving purposes of saving memory and reducing bandwidth.

Description

Panoramic image expansion method and system

Technical field

The present disclosure relates to image processing technologies, and in particular, to a panoramic image expansion method and system.

Background technique

With the rapid development of Virtual Reality (VR), the demand for panoramic images (including panoramic images and panoramic video, hereinafter collectively referred to as panoramic images) is increasing. To store and transmit panoramic images, it is necessary to have a spherical image of the panoramic image. The image is expanded and saved to a flat image. At present, the panoramic video industry mostly uses Equirectangular Projection, and the projected panoramic image is a 2:1 ratio image.

With a panoramic image projected by a spherical rectangle, a spherical image with a small area will be stretched to a large area. That is to say, a spherical image with a very low pixel is projected through a spherical rectangle and requires a larger planar image to be saved. If such an image is saved or transmitted, a larger memory and network bandwidth are required.

Summary of the invention

In order to solve the above problems, the present disclosure provides a panoramic image expansion method and system, which can ensure that the expanded two-dimensional image size is smaller than that of the current mainstream panoramic image expansion method without changing the planar image quality after expansion. size.

In a first aspect, the present disclosure provides a panoramic image expansion method, including the following steps:

The panoramic spherical image is divided into N spherical regions along N-1 latitude lines that can cut the warp into N equal parts. And projecting the N spherical regions separately to obtain N rectangles, and the whole of the N rectangles is a latitude expansion map, where N is a positive integer greater than the first threshold;

The latitude development map is divided into M spherical regions along the M-1 warp lines that can cut the weft into M equal parts, and the M spherical regions are respectively projected to obtain M hexagons, and are called The whole of the M hexagons is a longitude expansion map, where M is a positive integer greater than the second threshold;

The lower half of the hexagon of the longitude expansion map is transferred to the upper half of the hexagon of the longitude expansion map and spliced to obtain a panoramic plane image.

Optionally, the first threshold is 1000000 and the second threshold is 9999999.

Optionally, the first threshold is 1000 and the second threshold is 2000.

Optionally, the width of the picture on any one of the latitude expansion maps is equal to the circumference of the latitude of the panoramic spherical image.

Optionally, the N spherical regions are respectively projected by using a rectangular projection.

Optionally, the M spherical regions are respectively projected by using a straight approximation transformation.

Optionally, the curve approximation transforms the arc to be stretched or compressed into a straight line.

In another aspect, the present disclosure provides a panoramic image expansion system including a latitude cutting module configured to divide a panoramic spherical image into N spherical regions along N-1 latitude lines that can cut a warp into N aliquots, and The N spherical regions are respectively projected to obtain N rectangles, and the whole of the N rectangles is referred to as a latitude expansion map, where N is a positive integer of infinity;

The longitude cutting module is configured to divide the latitude development map into M spherical regions along M-1 warp lines that can cut the weft into M equal parts, and project the M spherical regions separately to obtain M spherical regions. a hexagon, and the entirety of the M hexagons is a longitude expansion map, where M is a positive integer of infinity;

a splicing module configured to uniformly transfer the lower half of the hexagon of the longitude development map to the Longitude expands the upper half of the hexagon of the figure and splices it to obtain a panoramic plane image.

Optionally, the first threshold is 1000000 and the second threshold is 9999999.

Optionally, the first threshold is 1000 and the second threshold is 2000.

Optionally, the curved approximation transform stretches or compresses the arc into a straight line.

In another aspect, the present disclosure provides a non-transitory storage medium storing computer executable instructions arranged to perform the panoramic image expansion method described above.

In another aspect, the present disclosure provides a computer program product comprising a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions when the program instructions are When executed, the computer is caused to perform the above-described panoramic image expansion method.

In another aspect, the present disclosure provides an electronic device comprising at least one processor and a memory communicatively coupled to the at least one processor, the memory for storing instructions executable by the at least one processor, When the instructions are executed by the at least one processor, the at least one processor is caused to perform the panoramic image expansion method described above.

The panoramic image unfolding method and system provided by the present disclosure ensure that the size of the expanded two-dimensional image is smaller than the size of the expanded image of the current mainstream panoramic image expansion method, and the memory is saved. And the purpose of reducing bandwidth, compared to rectangular projection, can greatly reduce redundant data.

DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present disclosure. Other drawings may also be obtained from those of ordinary skill in the art in light of the inventive work.

1 is a flowchart of a method for expanding a panoramic image disclosed in an embodiment of the present disclosure;

2 is a schematic diagram of a panoramic spherical image projection disclosed in an embodiment of the present disclosure as an iso-degree four-division panoramic expansion image;

3 is a schematic diagram of a panoramic spherical image projection disclosed in an embodiment of the present disclosure as an iso-degree N-partial panoramic expansion image;

4 is a schematic diagram of an equal-latitude N-partition panoramic expansion image projected into an equal-longitude halved panoramic expansion image and a projected image according to an embodiment of the present disclosure;

5 is a schematic diagram of an equal-latitude N-divided panoramic expanded image projected into an equal-longitude M equal-divided panoramic expanded image and a projected image disclosed in the embodiment of the present disclosure;

6 is a schematic diagram of a panoramic planar image after splicing of an equal-longitude M equal-divided panoramic image disclosed in an embodiment of the present disclosure;

7 is a frame diagram of a panoramic image expansion system disclosed in an embodiment of the present disclosure;

FIG. 8 is a structural block diagram of an electronic device disclosed in an embodiment of the present disclosure.

detailed description

The technical solutions in the embodiments of the present disclosure are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present disclosure. It is obvious that the described embodiments are only a part of the embodiments, and not all of the embodiments. This embodiment discloses a panoramic image expansion method and system. The following is a detailed description Bright.

Referring to FIG. 1, FIG. 1 is a flowchart of a method for expanding a panoramic image disclosed in this embodiment. In the present embodiment, the panoramic image is a panoramic spherical image, and the development process of the panoramic spherical surface is described by the expansion process of the spherical surface of the earth, and the concept of the earth latitude and longitude is cited to specifically explain the present disclosure.

In the present embodiment, the panoramic image expansion method includes steps S100 to 104.

In step S100, the panoramic spherical image is divided into N spherical regions by the equal latitude difference N-1 in the longitude, and the N spherical regions are respectively projected to obtain N rectangles, and the whole of the N rectangles is called the latitude. Expand the graph, where N is a positive integer of infinity;

In step S102, the latitude expansion map is divided into M spherical regions by latitude and longitude M-1, and M spherical regions are respectively projected to obtain M hexagons, which are called M hexagons. The whole is a longitude expansion map, where M is a positive integer of infinity;

In step S104, the lower half of the hexagon of the longitude expansion map is uniformly transferred to the upper half of the hexagon of the longitude expansion map and spliced to obtain a panoramic plane image.

Specifically, the width of the picture on any one of the latitude expansion maps is equal to the circumference of the corresponding latitude of the panoramic spherical image, and the N spherical areas are respectively projected using a rectangular projection.

Further, the M spherical regions are respectively projected by a straight approximation transformation, and the straight approximation transformation stretches or compresses the arc into a straight line.

In order to further illustrate the embodiments of the present disclosure, please refer to FIG. 2 , which is a schematic diagram of a panoramic spherical image projection disclosed in an embodiment of the present disclosure as an iso-latitude four-divided panoramic expansion image.

As described above, for convenience of description, the present embodiment still uses the unfolding process of the earth sphere to describe the unfolding process of the panoramic sphere, and cites the concept of the earth latitude and longitude.

Figure 2 shows that when N=4, the panoramic spherical image is projected into an iso-latitude quad-equal panoramic expansion image. Schematic diagram, as shown in the figure, the panoramic spherical image projection is obtained by rectangular projection to obtain an equal latitude quadrant panoramic expansion image, wherein the middle portion of the equal latitude quadrant panoramic expansion image is equal to the circumference of the panoramic spherical image, and The value of the equal latitude is πd/8.

When N is infinite, please refer to FIG. 3. FIG. 3 is a schematic diagram of the panoramic spherical image projection disclosed in the embodiment of the present disclosure as an equal-latitude N-half panoramic expansion image. As shown, the panoramic spherical image projection is obtained by rectangular projection to obtain an equally latitude N-partitioned panoramic expansion image, wherein the length of the zero latitude line in the equal-latitude N-partitioned panoramic expansion image is equal to the circumference of the panoramic spherical image. As can be seen from the figure, after a rectangular projection, the expansion ratio is 1:1.

Please refer to FIG. 4 . FIG. 4 is a schematic diagram of the equal-latitude N-divided panoramic expansion image projected into the equal-longitude halved panoramic expansion image and the projected image disclosed in the embodiment of the present disclosure. In the present embodiment, when M=2, the equal-latitude N-partitioned panoramic expansion image is projected, and at the same time, the straight-line approximation transformation is used to obtain an equal-longitude bisecting panoramic expansion image. Among them, the straight curve approximation is based on stretching or compressing the arc to a straight line.

Specifically, in FIG. 4, the broken line is a bisection panoramic expansion image, and the solid line is a bisected expanded projection image. As can be seen from the figure, 8 points of a certain latitude are respectively stretched and Compress the transform to get a hexagonal image. Among them, stretching from point A to point X, stretching from point B to point C to point Y, stretching from point D to point Z, compressing point E to point J, and compressing point F to K Point, compress the G point to M point, and compress the H point to N point. Further, the latitude line passing through four points A, B, C, and D on the arc is any latitude line, and between the latitude line and the zero latitude line passing through four points A, B, C, and D on the arc The points on all the arcs are stretched to obtain a line perpendicular to the zero latitude line, that is, the distance between the stretched lines is the equator length. Further, the points on all the arcs between the arc top and the latitude lines passing through the four points A, B, C, and D are compressed or stretched into a straight line, just as the point E is compressed to J point. Compress point F to point K, compress point G to point M, and compress point H to point N Shown.

In this way, the arc of the upper half of the arc is linearly transformed, that is, stretched and compressed to obtain a straight line figure.

Similarly, the points on the lower half of the arc corresponding to the upper semicircle are subjected to the same stretching and compression treatment to form two hexagons. It can be seen that after the halving expansion, two hexagons can be obtained.

Referring to FIG. 5 again, FIG. 5 is a schematic diagram of the equal-latitude N-partition panoramic expansion image projected into an equal-longitude M equal-divided panoramic expansion image and a projected image disclosed in the embodiment of the present disclosure. In the present embodiment, when M is infinite, each point on the arc at the same latitude is stretched by a method similar to that of FIG. 4. As shown in Fig. 5, a is stretched to x, b is stretched to y, and other points in the upper half of the arc are correspondingly stretched or compressed. Similarly, the other points in the lower half of the arc are stretched or compressed accordingly. The entire arc is compressed and stretched, resulting in an infinitely small hexagonal image.

Further, please refer to FIG. 6. FIG. 6 is a schematic diagram of a panoramic planar image after splicing of the equal-longitude M equal-divided panoramic image disclosed in the embodiment of the present disclosure.

When M is infinite, the lower half of the hexagon of the M-divided panoramic image is uniformly transferred to the upper half of the hexagon of the M-divided panoramic image and spliced to obtain a M-partition panoramic mosaic image.

After the above processing, the finally obtained panoramic plane image can greatly reduce redundant data, and save memory and reduce bandwidth, compared with the panoramic plane image directly obtained by rectangular projection.

Please refer to FIG. 7. FIG. 7 is a frame diagram of a panoramic image expansion system 70 disclosed in an embodiment of the present disclosure. In the present embodiment, the panoramic image is a panoramic spherical image, and the development process of the panoramic spherical surface is described by the expansion process of the spherical surface of the earth, and the concept of the earth latitude and longitude is cited to specifically explain the present disclosure. Specifically, the panoramic image expansion system 70 includes a latitude cutting module 701 and a longitude cutting module 703. And splicing module 705.

The latitude cutting module 701 is configured to divide the panoramic spherical image into N spherical regions by the equal latitude difference N-1 in the longitude, and project the N spherical regions separately to obtain N rectangles, and call the N rectangles as a whole. A latitude expansion diagram in which N is a positive integer of infinity.

The longitude cutting module 703 is configured to divide the latitude expansion map into M spherical regions by latitude and longitude M-1, and project the M spherical regions separately to obtain M hexagons, and call M six sides. The whole shape is a longitude expansion map, where M is a positive integer of infinity.

The splicing module 705 is arranged to uniformly transfer the lower half of the hexagon of the longitude expansion map to the upper half of the hexagon of the longitude expansion map and splicing to obtain a panoramic plane image.

The present disclosure also provides a non-transitory storage medium storing computer executable instructions arranged to perform the panoramic image expansion method of the above-described embodiments.

The present disclosure also provides a computer program product comprising a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions, when the program instructions are executed by a computer, The computer is caused to execute the panoramic image expansion method of the above embodiment.

The present disclosure also provides an electronic device. FIG. 8 is a structural block diagram of an electronic device according to an embodiment of the present disclosure. The electronic device may include a processor 81 and a memory 83, and may further include a communication interface 82 and a bus 84. The processor 81, the communication interface 82, and the memory 83 can complete communication with each other through the bus 84. Communication interface 82 can be used for information transfer. The processor 81 can call the logic instructions in the memory 83 to perform the panoramic image expansion method of the above embodiment.

In addition, the logic instructions in the memory 83 described above may be implemented in the form of a software functional unit and sold or used as a stand-alone product, and may be stored in a computer readable storage medium. Base In this understanding, the technical solution of the present disclosure may be embodied in the form of a software product stored in a storage medium, including a plurality of instructions for causing a computer device (which may be a personal computer, a server, or a network) The device or the like) performs all or part of the steps of the method described in various embodiments of the present disclosure. The foregoing storage medium may be a non-transitory storage medium, including: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk. A medium that can store program code, or a transitory storage medium.

After processing by each module in the panoramic image unfolding system, the resulting panoramic planar image greatly reduces redundant data relative to the panoramic planar image directly obtained by the rectangular projection, thereby achieving the purpose of saving memory and reducing bandwidth.

Claims

A panoramic image expansion method includes:

The panoramic spherical image is divided into N spherical regions along N-1 latitude lines which can cut the warp into N equal parts, and the N spherical regions are respectively projected to obtain N rectangles, and the N rectangles are called The entirety of the rectangle is a latitudinal expansion map, where N is a positive integer greater than the first threshold;

The latitude development map is divided into M spherical regions along the M-1 warp lines that can cut the weft into M equal parts, and the M spherical regions are respectively projected to obtain M hexagons, and are called The whole of the M hexagons is a longitude expansion map, where M is a positive integer greater than the second threshold;

The lower half of the hexagon of the longitude expansion map is transferred to the upper half of the hexagon of the longitude expansion map and spliced to obtain a panoramic plane image.
The panoramic image expansion method according to claim 1, wherein a width of a picture on any one of latitudes of the latitudinal expansion map is equal to a circumference of a corresponding latitude of the panoramic spherical image.
The panoramic image expansion method according to claim 2, wherein the N spherical regions are separately projected using a rectangular projection.
The panoramic image expansion method according to claim 2, wherein the M spherical regions are respectively projected by a straight approximation transformation.
The panoramic image expansion method according to claim 4, wherein the curve approximation is performed by stretching or compressing a circular arc into a straight line.
The panoramic image expansion method according to any one of claims 1 to 5, wherein the first threshold is 1000000, the second threshold is 9999999; or the first threshold is 1000, and the second threshold is 2000.
A panoramic image expansion system comprising:

The latitude cutting module is configured to divide the panoramic spherical image into N spherical regions along the N-1 latitude lines that can cut the warp into N equal parts, and project the N spherical regions separately to obtain N moments. Shape, and said the whole of the N rectangles is a latitudinal expansion diagram, wherein N is a positive integer of infinity;

The longitude cutting module is configured to divide the latitude development map into M spherical regions along M-1 warp lines that can cut the weft into M equal parts, and project the M spherical regions separately to obtain M spherical regions. a hexagon, and the entirety of the M hexagons is a longitude expansion map, where M is a positive integer of infinity;

The splicing module is configured to uniformly transfer the lower half of the hexagon of the longitude expansion map to the upper half of the hexagon of the longitude expansion map and splicing to obtain a panoramic plane image.
The panoramic image expansion system according to claim 7, wherein a width of a picture on any one of the latitude development maps is equal to a circumference of a latitude of the panoramic spherical image.
The panoramic image unfolding system according to claim 8, wherein the N spherical regions are separately projected using a rectangular projection.
The panoramic image development system according to claim 8, wherein the M spherical regions are respectively projected by a straight approximation transformation.
The panoramic image unfolding system according to claim 10, wherein said straight approximation transforms an arc to be stretched or compressed into a straight line.
The panoramic image expansion system according to any one of claims 7 to 11, wherein the first threshold is 1000000 and the second threshold is 9999999; or the first threshold is 1000 and the second threshold is 2000.
A non-transitory storage medium storing computer executable instructions arranged to perform the panoramic image expansion method of any of claims 1-6.
A computer program product comprising a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions that, when executed by a computer, cause the computer to execute The panoramic image expansion method according to any one of claims 1 to 6.
An electronic device comprising at least one processor and a memory communicatively coupled to the at least one processor, the memory for storing instructions executable by the at least one processor, the instructions being processed by the at least one When executed, the at least one processor is caused to perform the panoramic image expansion method according to any one of claims 1-6.