Narrow space point cloud absolute data acquisition method and model building equipment
Technical Field
The invention belongs to the field of engineering measurement, and particularly relates to a method for acquiring absolute data of point cloud in a narrow space and model building equipment, aiming at a scene that a large three-dimensional laser scanner is difficult to erect in the narrow space such as an upper step or an inverted arch in tunnel engineering construction for scanning.
Background
Tunnel geological conditions are severe, construction environment is complex, more inconvenience exists in construction management control, and the problem of overdrawing in the construction process becomes an important factor affecting tunnel construction cost. Therefore, the over-excavation degree of tunnel construction is effectively controlled, and timely and accurately mastering the data information of the profile surface of the tunnel construction becomes a key for solving the problem.
At present, a tunnel construction profile surface is mainly obtained through a section measurement mode, and mainly used instruments are a section instrument and a total station instrument, so that the efficiency of the method is low, and a great deal of time and labor are required. Compared with the traditional measuring method, the three-dimensional laser scanning technology provides a faster, safer and more effective investigation, measurement and monitoring method. The three-dimensional laser scanner can work in extremely complex space scenes, a large amount of acquired three-dimensional laser point cloud data are collected in a computer through fine scanning of the space, and then three-dimensional model construction is rapidly carried out on various non-standard and irregular large-scale entities through software. But the tunnel is of an elongated structure, and the three-dimensional laser scanner itself has precision requirements and scanning view angle limitations.
Thus, the data acquisition problem is a key problem in applying three-dimensional laser scanning techniques to tunnel engineering. Particularly, when the micro-step method is used for excavating, the visible angle of the upper-stage excavation surface space is small, the three-dimensional scanning measuring instrument cannot be arranged in a narrow space, the inverted arch excavation surface three-dimensional scanning measuring instrument is influenced by the depression angle measurement blind area, and precise scanning measurement is difficult.
Disclosure of Invention
The invention aims to provide a narrow space point cloud absolute data acquisition method, which aims to solve the problem that the cloud data of a construction contour surface point part is difficult to accurately acquire when a tunnel is excavated by a step method construction method in the background technology.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a method for acquiring absolute data of a point cloud in a narrow space comprises the following steps:
arranging control points in a tunnel construction section;
erecting a first scanner at a control point, establishing a measuring station under a tunnel construction global coordinate system, and scanning to obtain global point cloud data of a construction contour surface;
preprocessing global point cloud data acquired by a total station scanner, and comparing the global point cloud data with an actual contour surface to acquire a vacant area in which the contour surface point cloud data cannot be acquired;
moving and acquiring SLAM point cloud data comprising the point cloud data of the outline surface of the vacant area by using a second scanner;
registering SLAM point cloud data and global point cloud data, filling and fusing the SLAM point cloud data into the point cloud data of the gap area filled in the global point cloud data, and obtaining point cloud absolute data of the full-contour surface of the tunnel construction section.
As a preferred aspect, the narrow space point cloud absolute data acquisition method further includes the steps of: and establishing a three-dimensional model of the tunnel construction profile by using the absolute data of the point cloud of the tunnel construction section.
As a preferable aspect, the first scanner is a total station scanner, and the acquired point cloud coordinates are absolute data under a tunnel construction global coordinate system; the second scanner is a handheld SLAM device, the acquired point cloud coordinates are relative data under a point cloud space coordinate system taking the SLAM device as a center, each frame of point cloud is provided with a local coordinate system, each frame of data is registered to form a SLAM point cloud global space, and the coordinate system of the space is the SLAM point cloud global coordinate system.
As a preferred aspect, the step of registering SLAM point cloud data and global point cloud data is specifically implemented as:
projecting the point cloud data acquired by the handheld SLAM equipment to an SLAM point cloud global coordinate system by using a local coordinate system of each frame, and then completing positioning and splicing;
and registering the global point cloud data of the total station scanner and the spliced SLAM point cloud data to realize projection conversion from the SLAM point cloud global coordinate system to the tunnel construction global coordinate system.
As a preferred aspect, the step of registering the global point cloud data of the total station scanner and the spliced SLAM point cloud data to realize projection conversion from the SLAM point cloud global coordinate system to the tunnel construction global coordinate system is specifically implemented as follows: firstly, matching correspondence among point clouds is constructed through morphological characteristics of the measured part, and then, the projection conversion relation is estimated by adopting an AO algorithm based on point SHOT characteristics.
As a preferred aspect, the step of filling and fusing SLAM point cloud data into the point cloud data of the global point cloud data to fill the vacant area is specifically implemented as follows:
and converting the spliced SLAM point cloud data into a tunnel construction global coordinate system according to the projection conversion relation, and filling the converted SLAM data into the global point cloud data.
As a preferable aspect, the projection conversion relationship between the local coordinate system of each frame and the SLAM point cloud global coordinate system is:
wherein x is 1 、y 1 、z 1 Space coordinates in a local coordinate system of a certain frame of SLAM point cloud data; x is x 2 、y 2 、z 2 The space coordinates in the SLAM point cloud global coordinate system are obtained; x is x 0 、y 0 、z 0 The method comprises the steps that the offset of a local coordinate system origin of a certain frame of SLAM point cloud data relative to a global coordinate system origin of SLAM point cloud is performed;and the rotation angle parameters of all coordinate axes converted from a local coordinate system of a certain frame of SLAM point cloud data to a SLAM point cloud global coordinate system are obtained.
As a preferred aspect, the projection conversion relationship from the SLAM point cloud global coordinate system to the tunnel construction global coordinate system includes the following formula:
x, Y, Z is any space coordinate in a tunnel construction global coordinate system; x, y and z are space coordinates in the SLAM point cloud global coordinate system; x is X 0 、Y 0 、Z 0 Offset of the SLAM point cloud global coordinate system origin relative to the tunnel construction global coordinate system origin;the rotation angle parameters of all coordinate axes converted from the SLAM point cloud global coordinate system to the tunnel construction global coordinate system are obtained;and converting the scale factors for the SLAM point cloud global coordinate system to the tunnel construction global coordinate system.
As a preferred aspect, the handheld SLAM device includes a visual SLAM and/or a laser SLAM;
the step of acquiring SLAM point cloud data is implemented as:
the handheld SLAM equipment moves to acquire the contour face point cloud data, and acquires a plurality of point cloud data of the same position from different angles and different frames.
A narrow space point cloud absolute data acquisition and model establishment device comprises:
a control point arrangement unit for arranging control points at the tunnel construction section;
the global point cloud data acquisition unit is used for erecting a first scanner at the control point, establishing a station under a tunnel construction global coordinate system, and scanning to acquire global point cloud data of a construction contour surface;
the vacant area acquisition unit is used for preprocessing global point cloud data acquired by the total station scanner, comparing the actual profile surface and acquiring vacant areas without acquiring the profile surface point cloud data;
a SLAM point cloud data acquisition unit for acquiring SLAM point cloud data including the outline surface point cloud data of the vacant area by using the second scanner;
the point cloud absolute data computing unit is used for registering SLAM point cloud data and global point cloud data, filling and fusing the point cloud data of the outline surface of the vacant area into the global point cloud data, and obtaining the point cloud absolute data of the tunnel construction section.
The model building unit is used for building a three-dimensional model of the tunnel construction profile by utilizing the absolute data of the point cloud of the tunnel construction section.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, after partial point cloud data of the contour surface of tunnel construction is obtained by utilizing total station scanning in an open area of a narrow space such as a tunnel and the like, partial point cloud data of an upper excavation surface, an inverted arch and the like are obtained by utilizing small handheld SLAM equipment to carry out mobile measurement, and further registration and splicing are carried out, so that the absolute data acquisition of the point cloud in the narrow space is realized, the current contour surface information in the tunnel construction is timely, comprehensively and accurately obtained, high-precision data support is provided for effectively controlling the problems of tunnel construction overexcavation and the like, the digital management of the tunnel construction is realized, and positive benefits can be generated on the progress and quality of the construction.
Specific embodiments of the invention are disclosed in detail below with reference to the following description and drawings, indicating the manner in which the principles of the invention may be employed. It should be understood that the embodiments of the invention are not limited in scope thereby.
Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments in combination with or instead of the features of the other embodiments.
It should be emphasized that the term "comprises/comprising" when used herein is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is a schematic diagram of steps of a method for acquiring absolute data of a point cloud in a narrow space according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an apparatus module according to an embodiment of the present invention.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, shall fall within the scope of the invention.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, an embodiment of the invention provides a method for collecting absolute data of a point cloud in a narrow space, which includes the following steps:
s1, arranging control points in a tunnel construction section;
s2, erecting a first scanner at a control point, establishing a station under a tunnel construction global coordinate system, and scanning to obtain global point cloud data of a construction contour surface;
s3, preprocessing global point cloud data acquired by a total station scanner, and comparing the global point cloud data with an actual profile surface to acquire a vacant area where the profile surface point cloud data cannot be acquired;
s4, utilizing a second scanner to obtain SLAM point cloud data comprising point cloud data of the outline surface of the vacant area in a moving mode;
s5, registering the SLAM point cloud data and the global point cloud data, filling and fusing the SLAM point cloud data into the global point cloud data to fill the point cloud data of the vacant area, and obtaining absolute point cloud data of the tunnel construction section;
s6, establishing a three-dimensional model of the tunnel construction contour surface by utilizing the absolute data of the point cloud of the tunnel construction section.
In step S1, an engineering control network is introduced into a tunnel construction excavation section through wire measurement, and control points are arranged. The control points are mainly used for erecting a scanning instrument and acquiring absolute coordinate values of the point cloud in a tunnel construction coordinate system. The control point is generally in the center of the tunnel, so that the total station scanner can be conveniently erected, the visual field is wide, and the construction contour surface can be observed to the greatest extent.
The first scanner is a total station scanner. The global point cloud data acquired in step S2 is point cloud data in a tunnel construction global coordinate system (absolute coordinate system). In step S3, the actual profile surface is the tunnel profile surface in the current reality, and by comparing manually, a region that is not observed, such as a hole region in the point cloud of the upper excavation surface, the inverted arch, and the like, is found. The empty area is mainly an area which cannot be scanned by the total station scanner because of the problems of view angle and the like.
The second scanner is a handheld SLAM device. The handheld SLAM device includes a visual SLAM and/or a laser SLAM. The step S4 is implemented as follows: the handheld SLAM device moves to acquire contour surface point cloud data and acquires multiple (SLAM) point cloud data of the same location from different angles and different frames. The handheld SLAM equipment performs multi-frame shooting scanning at multiple positions and angles in the tunnel, and particularly focuses on measuring (SLAM) point cloud data of the vacant area obtained in the step S3. The handheld SLAM has low precision, but the equipment moves flexibly, but the absolute coordinate value of the point cloud cannot be directly obtained, so that SLAM point cloud data can cover a vacant area which cannot be scanned by a total station scanner, and further related data in the SLAM point cloud number can be filled into the total station cloud data to obtain the absolute data of the point cloud of the whole tunnel construction section.
In this embodiment, the step of registering SLAM point cloud data and global point cloud data is specifically implemented as the following sub-steps:
s51, projecting a local coordinate system of each frame of SLAM point cloud data of the handheld SLAM equipment to a global coordinate system of the SLAM point cloud space, and then completing positioning and splicing;
and S52, registering the global point cloud data of the total station scanner and the spliced SLAM point cloud data to realize projection conversion from the SLAM point cloud global coordinate system to the tunnel construction global coordinate system.
The step S52 is specifically implemented as: firstly, matching correspondence among point clouds is constructed through morphological characteristics of the measured part, and then, the projection conversion relation is estimated by adopting an AO algorithm based on point SHOT characteristics. The registration process can be iterated continuously, the coarse registration is evolved to the fine registration, and finally, the registration process is stopped through a judgment criterion.
In step S51, the projection conversion relationship between the local coordinate system of each frame and the SLAM point cloud global coordinate system is as follows:
wherein x is 1 、y 1 、z 1 Space coordinates in a local coordinate system of a certain frame of SLAM point cloud data; x is x 2 、y 2 、z 2 The space coordinates in the SLAM point cloud global coordinate system are obtained; x is x 0 、y 0 、z 0 The method comprises the steps that the offset of a local coordinate system origin of a certain frame of SLAM point cloud data relative to a global coordinate system origin of SLAM point cloud is performed;and the rotation angle parameters of all coordinate axes converted from a local coordinate system of a certain frame of SLAM point cloud data to a SLAM point cloud global coordinate system are obtained.
In step S52, the projection conversion relationship from the SLAM point cloud global coordinate system to the tunnel construction global coordinate system includes the following formula:
x, Y, Z is any space coordinate in a tunnel construction global coordinate system; x, y and z are space coordinates in the SLAM point cloud global coordinate system; x is X 0 、Y 0 、Z 0 Offset of the SLAM point cloud global coordinate system origin relative to the tunnel construction global coordinate system origin;the rotation angle parameters of all coordinate axes converted from the SLAM point cloud global coordinate system to the tunnel construction global coordinate system are obtained;and converting the scale factors for the SLAM point cloud global coordinate system to the tunnel construction global coordinate system.
Further, in the step S5, filling and fusing SLAM point cloud data into the global point cloud data to fill the vacant area is specifically implemented as follows: and converting the spliced SLAM point cloud data into a tunnel construction global coordinate system according to the projection conversion relation, and filling the converted SLAM data into the global point cloud data.
In the step, station scan data (global point cloud data) is taken as a reference, SLAM point cloud data is fused into the data, so that the conversion of SLAM point cloud data from relative coordinates to absolute coordinates is realized, and the SLAM point cloud data is fused into the global point cloud data, so that integral tunnel construction point cloud absolute data is formed.
In order to improve the accuracy of the point cloud registration, the method further comprises the steps of: a number (two or more) of targets are first deployed in the field and then registered using the co-named feature points of the targets in the global point cloud data and SLAM point cloud data. Accordingly, in step S51, the homonymous feature points of the target may be used to determine an offset of the local coordinate system origin of the SLAM point cloud data of different frames relative to the global coordinate system origin of the SLAM point cloud space, and in step S52, the homonymous feature points of the target may be used to determine an offset of the global coordinate system origin of the SLAM point cloud space relative to the tunnel construction global coordinate system origin.
Furthermore, the target with known size and shape characteristics can accurately extract the characteristic points of the target through an algorithm, and then the registration is carried out by utilizing the homonymous characteristic points of the target between two point clouds of total station scanning and SLAM, so that the registration precision can be effectively improved.
As shown in fig. 2, in one embodiment of the present invention, there is further provided a device for acquiring and modeling absolute data of a point cloud in a small space, including:
a control point arrangement unit for arranging control points at the tunnel construction section;
the global point cloud data acquisition unit is used for erecting a first scanner at the control point, establishing a station under a tunnel construction global coordinate system, and scanning to acquire global point cloud data of a construction contour surface;
the vacant area acquisition unit is used for preprocessing global point cloud data acquired by the total station scanner, comparing the actual profile surface and acquiring vacant areas without acquiring the profile surface point cloud data;
a SLAM point cloud data acquisition unit for acquiring SLAM point cloud data including the outline surface point cloud data of the vacant area by using the second scanner;
the point cloud absolute data computing unit is used for registering SLAM point cloud data and global point cloud data, filling and fusing the point cloud data of the outline surface of the vacant area into the global point cloud data, and obtaining tunnel construction point cloud absolute data;
the model building unit is used for building a three-dimensional model of the tunnel construction profile by utilizing the absolute data of the point cloud of the tunnel construction section.
Multiple elements, components, parts or steps can be provided by a single integrated element, component, part or step. Alternatively, a single integrated element, component, part or step may be divided into separate plural elements, components, parts or steps. The disclosure of "a" or "an" to describe an element, component, section or step is not intended to exclude other elements, components, sections or steps.
It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided will be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated herein by reference for the purpose of completeness. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to forego such subject matter, nor should the inventors regard such subject matter as not be considered to be part of the disclosed subject matter.