WO2021115299A1

WO2021115299A1 - Image collecting device for collecting 3d information and method of selecting same

Info

Publication number: WO2021115299A1
Application number: PCT/CN2020/134759
Authority: WO
Inventors: 左忠斌; 左达宇
Original assignee: 左忠斌
Priority date: 2019-12-12
Filing date: 2020-12-09
Publication date: 2021-06-17
Also published as: CN110986770A; CN110986770B

Abstract

An image collecting device (4) for collecting 3D information and a method of selecting the same. The image collecting device (4) is applicable to a 3D information collecting apparatus. The 3D information collecting apparatus comprises: a collecting region movement device for driving the image collecting device (4) to move such that a collecting region thereof moves relative to a target; and the image collecting device (4) for collecting a set of images of the target by means of relative movement, the image collecting device (4) satisfying a preset condition. The present invention increases both of a synthesizing speed and a synthesizing precision by selecting an appropriate camera, such that the measurements of angles and dimensions of a target are not required when selecting a camera, thus having high applicability.

Description

An image acquisition device for 3D information acquisition and its selection method

Technical field

The invention relates to the technical field of shape measurement, in particular to the technical field of 3D shape measurement.

Background technique

On the one hand, when performing 3D measurement, 3D information needs to be collected first. At present, commonly used methods include using machine vision to collect pictures of objects from different angles, and match these pictures to form a 3D model. When collecting pictures from different angles, multiple cameras can be set at different angles of the object to be measured, or pictures can be collected from different angles by rotating a single or multiple cameras. However, no matter which of these two methods, the problems of synthesis speed and synthesis accuracy are involved. The synthesis speed and synthesis accuracy are a contradiction to a certain extent. The increase of the synthesis speed will lead to the decrease of the final 3D synthesis accuracy; to improve the 3D synthesis accuracy, the synthesis speed needs to be reduced and more pictures are used to synthesize. In the prior art, in order to improve the synthesis speed and synthesis accuracy at the same time, it is usually realized by the method of optimizing the algorithm. In addition, the art has always believed that the way to solve the above-mentioned problems lies in the selection and update of algorithms. So far, no other methods have been proposed to improve the synthesis speed and synthesis accuracy at the same time. However, the optimization of the algorithm has reached a bottleneck. Before the emergence of a better theory, it has been impossible to both improve the synthesis speed and synthesis accuracy.

In the prior art, it has also been proposed to use empirical formulas including rotation angle, target size, and object distance to limit the camera position, so as to take into account the synthesis speed and effect. However, in practical applications, it is found that unless there is a precise angle measuring device, the user is not sensitive to the angle, and it is difficult to accurately determine the angle; the size of the target is difficult to accurately determine, especially in some applications where the target needs to be replaced frequently, and the tape is measured every time A lot of extra work is required, and professional equipment is required to accurately measure irregular targets. The measurement error leads to the camera position setting error, which will affect the acquisition and synthesis speed and effect; the accuracy and speed need to be further improved.

The above methods are to adjust various angles and distances after determining the camera to improve the synthesis speed and effect. However, no one realizes that for a 3D acquisition system, proper selection of camera parameters can also improve the speed and effect of 3D synthesis. Especially for some special occasions, the collection space is limited, the distance between the camera and the target is limited, and the camera's moving range is limited. In this case, no one mentions or gives any enlightenment on how to choose a camera.

On the other hand, in the current 3D acquisition system, the choice of camera is mainly based on the requirements of 2D shooting, such as object distance requirements, imaging quality, resolution, and so on. This angle of consideration is entirely in consideration of the quality of the flat image. However, in the field of 3D synthesis, it is not that the image quality is high, and the 3D model can be synthesized quickly and well, but it needs to be considered comprehensively according to the requirements of 3D synthesis. At present, no one considers how to choose a suitable camera from the perspective of 3D synthesis.

Therefore, there is an urgent need to solve the following technical problems: ①How to choose a suitable camera for the 3D acquisition system; ②How to balance the speed and effect of 3D synthesis through the selection of cameras.

Summary of the invention

In view of the above-mentioned problems, the present invention is proposed to provide a camera and a camera selection method used in a 3D acquisition system that overcomes the above-mentioned problems or at least partially solves the above-mentioned problems.

The present invention provides an image acquisition device used for 3D information acquisition and a selection method thereof. The image acquisition device is used in 3D information acquisition equipment;

The 3D information collection equipment includes: a collection area moving device for driving the collection area of the image collection device to move relative to the target object; an image collection device for collecting a set of images of the target object through the above-mentioned relative movement;

The focal length of the lens of the image acquisition device is mainly determined by the following formula:

0.73<δ<1.35

μ=0.983

Where L is the linear distance between the optical centers of the image acquisition device at two adjacent acquisition positions; f is the focal length of the image acquisition device; d is the rectangular length or width of the photosensitive element (CCD) of the image acquisition device; H is the optical center of the image acquisition device The distance from the optical axis to the surface of the target; δ and μ are the adjustment coefficients.

Optional, 0.85<δ<1.19

Optional, 1mm<f<150mm. .

Optional, 2mm<d<50mm.

Optionally, the image acquisition device includes a body and a lens.

Optionally, the image acquisition device is connected to the processor through data.

Optionally, the image acquisition device is a visible light camera or an infrared camera.

Optionally, the 3D information collection device further includes a processor for performing 3D synthetic modeling according to the image collected by the image collection device.

The present invention also provides a 3D acquisition device or method using any of the image acquisition devices.

The present invention also provides a 3D synthesis device or method using any of the image acquisition devices.

Invention points and technical effects

1. For the first time, it is proposed to improve the synthesis speed and synthesis accuracy by selecting a suitable camera.

2. When choosing a camera, there is no need to measure the angle, no need to measure the target size, and the applicability is stronger.

Description of the drawings

By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only used for the purpose of illustrating the preferred embodiments, and are not considered as a limitation to the present utility model. Also, throughout the drawings, the same reference symbols are used to denote the same components. In the attached picture:

Figure 1 is a schematic diagram of an image acquisition device in Embodiment 1 of the present invention;

Figure 2 is a schematic diagram of a 3D acquisition system in Embodiment 2 of the present invention;

3 is a schematic diagram of another implementation manner of the 3D acquisition system in Embodiment 2 of the present invention;

The corresponding relationship between the reference signs and the components is as follows:

1 target, 2 stage, 3 rotation device, 4 image acquisition device, 5 support.

Detailed ways

Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although the drawings show exemplary embodiments of the present disclosure, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

Embodiment 1: A 3D system that collects by the relative movement of the camera and the target

An embodiment of the present invention provides an image acquisition device for 3D information acquisition, including an image acquisition device and a rotation device. The image acquisition device is used to acquire a set of images of the target through the relative movement of the acquisition area of the image acquisition device and the target; the acquisition area moving device is used to drive the acquisition area of the image acquisition device to move relative to the target. The acquisition area is the effective field of view range of the image acquisition device.

Please refer to FIG. 1, the target 1 is fixed on the stage 2, and the rotating device 3 drives the image acquisition device 4 to rotate around the target 1. The rotating device 3 can drive the image capturing device 4 to rotate around the target 1 through a rotating arm. Of course, this kind of rotation is not necessarily a complete circular motion, and it can only be rotated by a certain angle according to the collection needs. Moreover, this rotation does not necessarily have to be a circular motion, and the motion trajectory of the image acquisition device 4 can be other curved trajectories, as long as it is ensured that the camera shoots the object from different angles. The rotating device 3 can be in various forms such as a cantilever, a turntable, or a track, so that the image acquisition device can move.

In this case, the distance between the position of the camera to be installed and the target object can be measured or determined according to the size of the objective space. The collection position of the camera can be set in advance, which is related to the difficulty of servo control. For example, frequent start and stop at small intervals will increase the difficulty of servo control. Therefore, the camera acquisition location is usually selected according to the control needs. After determining the above parameters, you can choose a suitable camera according to the time and effect of 3D synthesis. For the selection of the camera, the most important parameters are two parameters: the size of the photosensitive element and the focal length of the lens. After the image quality and resolution are determined, the size d of the photosensitive element can be determined, and the focal length of the lens is mainly determined by the following formula:

Where L is the linear distance between the optical centers of the image acquisition device at two adjacent acquisition positions; f is the focal length of the image acquisition device; d is the rectangular length or width of the photosensitive element (CCD) of the image acquisition device; H is the optical center of the image acquisition device The distance from the optical axis to the surface of the target; δ and μ are the adjustment coefficients. The value range of δ is: 0.73<δ<1.35, μ=0.983. Preferably, 0.85<δ<1.19.

It can be understood that since the focal length of cameras on the market is not an arbitrary value, it is limited by manufacturing and design. Therefore, after the calculation according to the above formula is completed, it should meet the production requirements, that is, it may not be directly equal to the formula, but near the calculated value of the formula. For example, the calculated value is 51.8mm, and a 50mm lens can be selected.

For example, when used for 3D acquisition in a narrow space, such as the human oral cavity (or the cavity of some industrial parts). The space around the target is very small. Assuming the ideal is a cube of size M×M×M, the maximum distance between the camera and the target has been limited and cannot exceed M. For a certain degree of redundancy, usually no more than 0.8M. The target is still momentarily, but the long-term morphology will change. At this time, there is also a certain limit on the number of captured images. You cannot capture too much, otherwise it will cause a long delay and the morphology of the target itself will change. And produce errors. Therefore, the number of images that can be collected is also limited, and it can be calculated that the distance between adjacent positions where two images are collected is limited. In this case, if you choose a camera according to the idea of taking a flat picture, you can only get a high-quality flat image, but whether it can synthesize a 3D model is not guaranteed. Therefore, the present invention proposes to use the above empirical conditions to select camera parameters under the above circumstances, so as to ensure the speed and effect of 3D model synthesis.

In addition to the above methods, the camera can also be fixed in some cases. As shown in Figure 2, the stage carrying the target rotates so that the direction of the target facing the image capture device changes from time to time, so that the image capture device can capture from different angles. Target image. However, when calculating at this time, the calculation can still be carried out according to the situation converted into the movement of the image acquisition device, so as to select a suitable camera.

The system also includes a processor, also called a processing unit, which is used to synthesize a 3D model of the target object according to a 3D synthesis algorithm according to a plurality of images collected by the image acquisition device to obtain 3D information of the target object.

Embodiment 2: A 3D system that collects by multiple cameras at fixed positions

There is also a 3D acquisition system, as shown in Figures 2 and 3, which includes a plurality of image acquisition devices 4 whose positions are relatively fixed. For example, on a circular support 5, a plurality of image acquisition devices 4 are fixed along the circumference, and Their optical axes are all toward the center of the circular bracket. Of course, the above description is only for ease of understanding. It is conceivable that the bracket is not necessarily a complete circle. For example, when only a 3D model of the target part is required, as shown in FIG. 3, the bracket may be a part of an arc. Moreover, there is not necessarily only one bracket, and there may be multiple brackets, and each bracket has a certain number of cameras, so that the cameras are distributed in a two-dimensional space.

In this case, the distance between the cameras has been fixed by the bracket. Once the bracket is constructed, it is inconvenient to disassemble and modify it. At this time, it can be considered that the distance between the cameras is limited. Then according to the distance of the 3D acquisition system from the acquisition object, a suitable camera can be selected for installation. Specifically, the above conditions should also be met.

Camera selection method

Step 1: Determine the distance T between the camera's photosensitive element and the surface of the target. Usually, the distance is affected by the collection environment, and the T value is also small for the case where the space is small. According to the limitation of space size, T value can be determined. Of course, it is not necessary to have limited space to determine the T value. Users can choose T value according to actual needs.

Step 2: Determine the distance L between the optical centers of the cameras at two adjacent acquisition positions, or the distance L between the optical centers of two adjacent cameras; usually due to the difficulty of motion control and the limitation of the camera arrangement density, L is subject to Limited, and can be determined. Of course, it is not necessary to be restricted to determine the value of L. Users can choose the value of L according to actual needs.

third step:

Determine the size of the camera's photosensitive element and lens focal length based on the above empirical conditions.

Although the foregoing embodiments describe that the image capture device captures images, it should not be construed as being only applicable to a group of pictures composed of a single picture, and this is only an illustrative method for ease of understanding. The image acquisition device 4 can also acquire video data, directly use the video data or intercept images from the video data for 3D synthesis. However, the shooting position of the corresponding frame of the video data or the captured image used in the synthesis still satisfies the above empirical formula.

The above-mentioned target object, target object, and object all represent objects for which three-dimensional information is pre-acquired. It can be a physical object, or it can be a combination of multiple objects. For example, it can be a head, a hand, and so on. The three-dimensional information of the target includes a three-dimensional image, a three-dimensional point cloud, a three-dimensional grid, a local three-dimensional feature, a three-dimensional size, and all parameters with a three-dimensional feature of the target. The so-called three-dimensional in the present invention refers to three-direction information of XYZ, especially depth information, which is essentially different from only two-dimensional plane information. It is also essentially different from the definitions called three-dimensional, panoramic, holographic, and three-dimensional, but actually only include two-dimensional information, especially depth information.

The collection area mentioned in the present invention refers to the range that an image collection device (such as a camera) can shoot. The image acquisition device in the present invention can be CCD, CMOS, camera, video camera, industrial camera, monitor, camera, mobile phone, tablet, notebook, mobile terminal, wearable device, smart glasses, smart watch, smart bracelet and belt All devices with image capture function.

In the instructions provided here, a lot of specific details are explained. However, it can be understood that the embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures, and technologies are not shown in detail, so as not to obscure the understanding of this specification.

Similarly, it should be understood that in order to simplify the present disclosure and help understand one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, Figure, or its description. However, the disclosed method should not be interpreted as reflecting the intention that the claimed invention requires more features than those explicitly stated in each claim. More precisely, as reflected in the following claims, the inventive aspect lies in less than all the features of a single embodiment disclosed previously. Therefore, the claims following the specific embodiment are thus explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present invention.

Those skilled in the art can understand that it is possible to adaptively change the modules in the device in the embodiment and set them in one or more devices different from the embodiment. The modules or units or components in the embodiments can be combined into one module or unit or component, and in addition, they can be divided into multiple sub-modules or sub-units or sub-components. Except that at least some of such features and/or processes or units are mutually exclusive, any combination can be used to compare all features disclosed in this specification (including the accompanying claims, abstract and drawings) and any method or methods disclosed in this manner or All the processes or units of the equipment are combined. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose.

In addition, those skilled in the art can understand that although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments means that they fall within the scope of the present invention. And form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

The various component embodiments of the present invention may be implemented by hardware, or by software modules running on one or more processors, or by a combination of them. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) may be used in practice to implement some or all of the functions based on some or all of the components in the device of the present invention according to the embodiments of the present invention. The present invention can also be implemented as a device or device program (for example, a computer program and a computer program product) for executing part or all of the methods described herein. Such a program for realizing the present invention may be stored on a computer-readable medium, or may have the form of one or more signals. Such a signal can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the present invention, and those skilled in the art can design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be constructed as a limitation to the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of multiple such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims listing several devices, several of these devices may be embodied in the same hardware item. The use of the words first, second, and third, etc. do not indicate any order. These words can be interpreted as names.

So far, those skilled in the art should realize that although multiple exemplary embodiments of the present invention have been illustrated and described in detail herein, they can still be disclosed according to the present invention without departing from the spirit and scope of the present invention. The content directly determines or derives many other variations or modifications that conform to the principles of the present invention. Therefore, the scope of the present invention should be understood and deemed to cover all these other variations or modifications.

Claims

An image acquisition device for 3D information acquisition, characterized in that:

The image acquisition device is used in 3D information acquisition equipment;

The 3D information collection equipment includes: a collection area moving device for driving the collection area of the image collection device to move relative to the target object; an image collection device for collecting a set of images of the target object through the above-mentioned relative movement;

The focal length of the lens of the image acquisition device is mainly determined by the following formula:

0.73<δ<1.35

μ=0.983

Where L is the linear distance between the optical centers of the image acquisition device at two adjacent acquisition positions; f is the focal length of the image acquisition device; d is the rectangular length or width of the photosensitive element of the image acquisition device; H is the optical center of the image acquisition device along the optical axis The distance to the surface of the target; δ and μ are the adjustment coefficients.
The device according to claim 1, characterized in that: 0.85<δ<1.19.
The device according to claim 1, characterized in that: 1mm<f<150mm.
The device according to claim 1, characterized in that: 2mm<d<50mm.
The device of claim 1, wherein the image acquisition device includes a body and a lens.
The device according to claim 1, wherein the image acquisition device is connected to the processor through data.
The device of claim 1, wherein the image acquisition device is a visible light camera or an infrared camera.
8. The device according to claim 1, wherein the 3D information collection device further comprises a processor, configured to perform 3D synthetic modeling according to the image collected by the image collection device.
A 3D information collection device, characterized in that the image collection device according to any one of claims 1-8 is used.
A 3D information synthesis device, characterized in that the image acquisition device according to any one of claims 1-8 is used. .
A method for selecting an image acquisition device for 3D information acquisition, characterized in that:

The image acquisition device is used in 3D information acquisition equipment;

The 3D information collection equipment includes: a collection area moving device for driving the collection area of the image collection device to move relative to the target object; an image collection device for collecting a set of images of the target object through the above-mentioned relative movement;

The focal length of the lens of the image acquisition device is mainly determined by the following formula:

0.73<δ<1.35

μ=0.983

Where L is the linear distance between the optical centers of the image acquisition device at two adjacent acquisition positions; f is the focal length of the image acquisition device; d is the rectangular length or width of the photosensitive element of the image acquisition device; H is the optical center of the image acquisition device along the optical axis The distance to the surface of the target; δ and μ are the adjustment coefficients.
The selection method according to claim 11, characterized in that: 0.85<δ<1.19.
The selection method according to claim 11, characterized in that: 1mm<f<150mm.
The selection method according to claim 11, wherein: 2mm<d<50mm.
The selection method according to claim 11, wherein the image acquisition device includes a body and a lens.
11. The selection method of claim 11, wherein the image acquisition device is connected to the processor through data.
11. The selection method of claim 11, wherein the image acquisition device is a visible light camera or an infrared camera.
11. The selection method according to claim 11, wherein the 3D information collection device further comprises a processor, configured to perform 3D synthetic modeling according to the image collected by the image collection device.
A method for collecting 3D information, which is characterized by using the method for selecting an image collecting device according to any one of claims 11-18.
A 3D information synthesis method, characterized in that the selection method of the image acquisition device according to any one of claims 11-18 is used.