CN111009036A

CN111009036A - Grid map correction method and device in synchronous positioning and map construction

Info

Publication number: CN111009036A
Application number: CN201911256857.9A
Authority: CN
Inventors: 李保明; 张一凡; 王学强; 张富强
Original assignee: Goertek Inc
Current assignee: Goertek Inc
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2020-04-14
Anticipated expiration: 2039-12-10
Also published as: CN111009036B

Abstract

The invention discloses a grid map correction method and device in synchronous positioning and map construction. The method comprises the following steps: when the current scene at least comprises part of artificial environment is judged, correction is started, and a grid map of the current scene and a Computer Aided Design (CAD) drawing of the current scene are obtained; aligning the grid map with the CAD graph based on an image matching method of the feature points; identifying a connected domain in the grid map, and determining a mapping domain corresponding to the connected domain in the aligned CAD graph according to a mapping relation; extracting high-level features indicating a certain geometric shape in the CAD graph according to the mapping domain; and mapping the extracted high-level features in the grid map, and correcting the grid map. Compared with a manual correction method, the correction scheme is more accurate and efficient, so that the accuracy of the grid map and the reliability of positioning navigation of robots, unmanned vehicles and the like are improved.

Description

Grid map correction method and device in synchronous positioning and map construction

Technical Field

The invention relates to the technical field of synchronous positioning and map construction, in particular to a grid map correction method and device in synchronous positioning and map construction, electronic equipment and a readable storage medium.

Background

SLAM (synchronous positioning and map construction) refers to a process of simultaneously calculating the position of a moving object and constructing an environment map according to information of a sensor, and solves the problems of positioning and map construction when a robot, an unmanned vehicle and the like move in an unknown environment. Due to the difference of the types and installation modes of the sensors, the implementation mode and difficulty of the SLAM have certain difference, and the laser SLAM collects cloud points and does not need to collect three-dimensional depth information like VSLAM, so that the calculation performance of the laser SLAM is greatly lower than that of VSLAM, the algorithm is simple, and the laser SLAM is widely applied to the field of unmanned aerial vehicle control at present.

However, due to the limitation of the type and performance of the laser radar, the map constructed by the laser has some differences from the actual scene, for example, the laser radar has low frequency, which causes some areas to be unable to collect, and the laser radar has high noise, which causes the wall map to be bent and other abnormal conditions, which can seriously affect the positioning and navigation functions of the robot. At present, the occupied grid map constructed by the laser SLAM is usually corrected manually, and the method corrects the map to a certain extent, but has the disadvantages of large artificial factor, artificial error and low efficiency.

Disclosure of Invention

In view of the above, the present invention is proposed to provide a method, an apparatus, an electronic device and a readable storage medium for correcting a grid map in synchronous positioning and mapping, which overcome or at least partially solve the above problems.

According to one aspect of the present invention, there is provided a method for correcting a grid map in synchronous positioning and mapping, the method comprising:

when the current scene at least comprises part of artificial environment is judged, correction is started, and a grid map of the current scene and a Computer Aided Design (CAD) drawing of the current scene are obtained;

aligning the grid map with the CAD graph by an image matching method based on the feature points;

identifying a connected domain in the grid map, and determining a mapping domain corresponding to the connected domain in the aligned CAD graph according to the mapping relation;

extracting high-level features indicating a certain geometric shape in the CAD graph according to the mapping domain;

and mapping the extracted high-level features in a grid map, and correcting the grid map.

Optionally, aligning the grid map and the CAD drawing by using the feature point-based image matching method includes:

respectively extracting ORB characteristic points from the CAD graph and the grid map, wherein the ORB characteristic points comprise key pixel points and descriptors of the key pixel points are calculated;

determining matched feature point pairs through the descriptors;

determining the change values of the scale and the direction of the CAD graph through least square fitting according to the characteristic point pairs;

and aligning the CAD graph with the grid map according to the change values of the scale and the direction.

Optionally, the determining the matched feature point pair through the descriptor includes:

and traversing key pixel points in the grid map and the CAD map, calculating the Euclidean distance of key pixel point descriptors in the grid map and the CAD map according to bitwise and arithmetic, and determining the key pixel point pair with the minimum Euclidean distance value as a matched feature point pair.

Optionally, determining the change value of the scale and the direction of the CAD drawing by least square fitting according to the feature point pair includes:

obtaining a characteristic point pair;

respectively connecting two corresponding characteristic points in the CAD graph and the grid map to determine a connecting line;

calculating the ratio of each corresponding connecting line;

and fitting each ratio by a least square method to determine a scale change value and a direction change value suitable for adjusting the CAD graph.

Optionally, mapping the extracted high-level features in a grid map includes:

and mapping the high-level features in the CAD map into a grid map according to the corresponding positions and directions and the coordinate transformation relation.

Optionally, the modifying the grid map includes:

determining a mathematical expression of the high-level feature according to pixel information of feature points in the high-level feature and a linear regression method;

and adjusting the scale and the direction of the high-level features according to the mathematical expression to obtain the optimized high-level features.

Optionally, the modifying the grid map further includes:

adding pixel points in a preset neighborhood of the high-level features to realize the rendering of the high-level features;

and fusing each rendered high-level feature with the adjacent feature of the high-level feature, thereby updating the grid map.

According to another aspect of the present invention, there is provided a device for correcting a grid map in synchronous positioning and mapping, the device comprising:

the image acquisition unit is suitable for starting correction when judging that the current scene at least comprises part of artificial environment, and acquiring a grid map of the current scene and a Computer Aided Design (CAD) drawing of the current scene;

the image alignment unit is suitable for aligning the grid map with the CAD graph based on an image matching method of the feature points;

the mapping unit is suitable for identifying the connected domain in the grid map and determining the mapping domain corresponding to the connected domain in the aligned CAD graph according to the mapping relation;

the feature extraction unit is suitable for extracting high-level features which indicate a certain geometric shape in the CAD graph according to the mapping domain;

and the map correction unit is suitable for mapping the extracted high-level features in the grid map and correcting the grid map.

Optionally, the image alignment unit is adapted to:

determining matched feature point pairs through the descriptors;

Optionally, the high-level features include any one or more of the following: straight lines, broken lines, polygons, curves, ellipses, circles.

In accordance with still another aspect of the present invention, there is provided an electronic apparatus including: a processor; and a memory arranged to store computer executable instructions that, when executed, cause the processor to perform a method as any one of the above.

According to yet another aspect of the invention, there is provided a computer readable storage medium, wherein the computer readable storage medium stores one or more programs which, when executed by a processor, implement the method as any one of above.

Therefore, the correction scheme disclosed by the invention is more accurate and efficient than a manual correction method, so that the accuracy of a grid map and the reliability of positioning navigation of robots, unmanned vehicles and the like are improved.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

fig. 1 is a flowchart illustrating a method of correcting a grid map according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram illustrating a correction apparatus of a grid map according to an embodiment of the present invention;

FIG. 3 shows a schematic structural diagram of an electronic device according to one embodiment of the invention;

FIG. 4 shows a schematic structural diagram of a computer-readable storage medium according to one embodiment of the invention;

FIG. 5 illustrates a classification diagram of an application scenario to which laser mapping is facing, according to one embodiment of the present invention;

FIG. 6 illustrates a flow diagram for CAD drawing and grid map alignment, according to one embodiment of the present invention;

FIG. 7 illustrates an exemplary diagram of grid map and CAD map feature point correspondences, in accordance with one embodiment of the present invention;

FIG. 8 illustrates a flow diagram of connected domain analysis and mapping according to one embodiment of the invention;

FIG. 9 illustrates an exemplary flow diagram for mapping high-level features according to one embodiment of the invention;

FIG. 10 illustrates an exemplary diagram of a high-level feature map according to one embodiment of the invention;

FIG. 11 is a flow diagram illustrating linear fitting and fusion of a high-level feature set in a grid map, according to an embodiment of the invention;

FIG. 12 illustrates an exemplary diagram of fitting, rendering, of high-level features according to one embodiment of the invention.

Detailed Description

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Fig. 1 is a flowchart illustrating a method of correcting a grid map according to an embodiment of the present invention; the method comprises the following steps:

and step S110, when the current scene at least comprises a part of artificial environment, starting correction, and acquiring a grid map of the current scene and a CAD (computer aided design) drawing of the current scene.

One of the maps constructed by the laser SLAM is an occupancy grid map, which is constructed by continuously updating the occupancy state of a grid, such as the grid map shown on the left side in fig. 7, where gray is a position area, white is a non-obstacle area, black is an obstacle area, and the darker the color is, the greater the probability of representing an obstacle is. In the prior art, a map is not constructed by combining features of higher levels, so that the influence of sensor noise is large.

Referring to fig. 5, for an environment to which the SLAM faces, the environment may be roughly divided into a natural environment and an artificial environment according to a geometric characteristic. The geometric shapes in the natural environment are mainly represented by random features, while in the artificial environment, due to artificial design, the environment geometric structures often have obvious regularity, for example, a large number of geometric elements such as straight lines, curves and circular arcs exist, particularly, a large number of regular geometric figures exist in an indoor constructed laser grid map, and on the other hand, such features exist in a large number of scene CAD (computer aided design) maps. Therefore, the grid map and the corresponding CAD graph formed according to the acquisition of the laser sensor are obtained, the grid map is corrected by the CAD graph in the indoor scene, and the aim of referring to the CAD graph is to optimize the artificial environment part in the grid map.

The scheme of the embodiment is suitable for the situation that the scene is an artificial environment, such as the map construction of an indoor scene, and is also suitable for the situation that a part of the artificial environment is an artificial environment and a part of the artificial environment is a natural environment.

And step S120, aligning the grid map with the CAD graph by using an image matching method based on the feature points.

In the case of a CAD map of an indoor environment and a grid map constructed by laser SLAM, dimensions and directions may be inconsistent, and at this time, alignment needs to be performed by an image matching method based on pixel-level feature points. The purpose of the alignment is to keep the dimensions and orientation of the CAD drawing consistent with those of the grid map.

Referring to fig. 6, a specific step of alignment is disclosed, which includes obtaining feature points in the CAD drawing and the grid map, respectively, and matching the feature points so that their dimensions and directions are the same or corresponding to each other, thereby achieving the purpose of dimension or direction alignment, and obtaining the aligned CAD drawing.

And step S130, identifying the connected domain in the grid map, and determining a mapping domain corresponding to the connected domain in the aligned CAD graph according to the mapping relation.

The connected domain analysis is to analyze the connected domain of the grid map to find the reachable area of the robot, such as the white non-obstacle area in the left part of fig. 7, that is, the connected domain.

Fig. 8 shows a process for obtaining a map domain (connected domain) in a CAD drawing from a connected domain in a grid map. The connected domain mapping is that after the images are aligned, the CAD graph and the grid map are pictures with the same or corresponding size and direction, and the mapping result is that the connected domain is mapped into a mapping domain in the CAD graph.

And step S140, extracting high-level features indicating a certain geometric shape in the CAD graph according to the mapping domain.

There are a large number of high-level features in indoor scenes, such as lines, curves, circles, etc. The embodiment of the invention performs high-level feature extraction and mapping on the mapped CAD graph so as to correct the grid map later.

And step S150, mapping the extracted high-level features in a grid map, and correcting the grid map.

The method comprises the steps of mapping the high-level features on the grid map, determining the high-level features in the grid map, and then performing fitting correction, rendering and fusion on the high-level features, so that the grid map is updated.

In conclusion, the grid map correction scheme disclosed in the embodiment can obtain more accurate and efficient technical effects than a manual correction method, so that the accuracy of synchronous positioning and map construction is ensured, and the reliability of robot positioning and navigation is improved.

In one embodiment, referring to FIG. 6, the specific steps of aligning a grid map with a CAD drawing are shown.

First, feature point extraction is performed on a CAD drawing and a grid map, and in order to perform feature point matching, this embodiment is described by taking orb (organized FAST and specified bridge) feature points and descriptors as an example.

And respectively extracting ORB characteristic points from the CAD graph and the grid map, wherein the ORB characteristic points comprise extracting key pixel points and calculating descriptors of the key pixel points.

In fig. 7, the grid map is on the left side, the CAD map is on the right side, the connecting lines respectively indicate two pairs of corresponding feature points, and the feature points are extracted from the CAD map and the grid map. Extracting the ORB features includes extracting key pixel points and calculating a descriptor of the key points, for example, the descriptor may be a binary value consisting of 256 bits of 0 and 1.

The feature point matching is performed by the ORB feature point descriptor, and the euclidean distance of the descriptor is calculated, for example, a bitwise and operation method may be adopted, and the smaller the bitwise and value is, the closer the distance between the two key points is indicated, and the similarity of the feature points may be obtained.

When the method is implemented, all key pixel points in the CAD graph and the grid map can be traversed. When n pairs (above a certain threshold) of feature point pairs are found, the scale and direction changes can be obtained by a least square method.

And determining the change value of the scale and the direction of the CAD graph through least square fitting according to the characteristic point pairs. Two pairs of feature points marked in fig. 7 are for example, the left grid map is a (Xa, Ya), B (Xb, Yb), the right CAD map is a '(Xa', Ya '), B' (Xb ', Yb'), a1 ═ AB/a ', B', and a matching feature point C is added in the same manner, and then a2 and a3 can be obtained according to the feature point a and the feature point C, and the feature point B and the feature point C. And fitting a1, a2, a3 and the like by a least square method to obtain an optimal scale change value and direction change value which are adaptive to the whole image. Alternatively, the feature points of the part may be used to obtain an optimal scale change value and direction change value adapted to the part of the region in the image.

And adjusting the CAD graph into an image consistent with the grid map according to the scale change value and the direction change value to obtain the aligned CAD graph.

In one embodiment, mapping the extracted high-level features in a grid map comprises: and mapping the high-level features in the CAD map into a grid map according to the corresponding positions and directions and the coordinate transformation relation.

The robot carries out positioning and navigation according to the grid map, so a connected domain exists in the grid map, the robot can move freely, and map correction is mainly carried out on the connected domain. Therefore, the connected domain needs to be extracted and the CAD drawing mapping is performed, and the specific process thereof, referring to fig. 8, specifically includes analyzing the connected domain of the grid map, and then determining the mapping domain corresponding to the connected domain in the aligned CAD drawing, thereby determining the mapping domain in the mapped CAD.

After the mapping domain of the CAD is obtained, the boundary of the mapping domain is extracted according to the mapping domain, and the boundary generally consists of linear high-level features such as straight lines or curves.

Fig. 9 shows a process of mapping corresponding features in the grid map according to the linear features of the CAD, including extracting high-level features according to the CAD mapping domain, classifying the extracted high-level features, and then mapping the high-level features into the grid map, thereby obtaining a high-level feature set in the grid map.

The feature classification is mainly to divide high-level features extracted from the CAD graph into straight line features, circle features and the like. The feature mapping is to map the position of the high-level feature extracted from the CAD drawing to the grid map, and the mapping is generally implemented by transforming according to the coordinate position relationship of the two drawings, and specifically, the high-level feature in the CAD drawing can be drawn to the corresponding position of the grid map. Fig. 10 shows an exemplary diagram of mapping to a grid map when a hierarchical feature in a CAD drawing is a straight line shape, and fig. 10 enlarges the straight line (indicated by an arrow in the drawing) for convenience of illustration.

In one embodiment, step S150 includes: determining a mathematical expression of the high-level feature according to pixel information of feature points in the high-level feature and a linear regression method; and adjusting the scale and the direction of the high-level features according to the mathematical expression to obtain the optimized high-level features.

Modifying the grid map further comprises: adding pixel points in a preset neighborhood of the high-level features to realize the rendering of the high-level features; and fusing each rendered high-level feature with the adjacent feature of the high-level feature, thereby updating the grid map.

Fig. 11 shows a flow of performing modification optimization on a grid map, which specifically includes: and performing linear regression fitting on linear features in the grid map according to the high-level feature set in the grid map, and then fusing the fitted features with other features to obtain an updated map. Namely, two kinds of processing are carried out on the high-level features in the grid map: and firstly, linear regression fitting and secondly, rendering and fusing the fitted features.

The linear regression fitting means that for each high-level feature, a mathematical function is obtained according to linear regression according to each feature point in the feature and a plurality of feature points of adjacent domains of the feature, and the scale and the direction of the feature are secondarily adjusted according to an expression of the mathematical function, so that the error or deviation of the high-level feature is corrected.

Therefore, the determining the mathematical expression of the high-level feature according to the linear regression method specifically includes: the features are fitted to a mathematical expression, taking the leftmost vertical direction straight line in fig. 10 as an example, assuming that the abscissa direction x is 5 (the ordinate direction 5< y <9), and then the mathematical expression is converted into pixel information of the corresponding position. Thus avoiding errors or deviations in the line shape characteristic itself.

Rendering and fusing the linear features specifically comprises: and adding appropriate pixel points around the linear feature according to a preset threshold value, widening the linear feature, and fusing the feature and the similar feature to meet the requirement of the grid map, thereby realizing the correction and the update of the grid map.

Referring to fig. 12, the left image is the original grid map; the middle graph is a high-level feature extracted from the CAD graph; the right graph is the rendered high-level features.

Fig. 2 is a schematic structural diagram illustrating a correction apparatus of a grid map according to an embodiment of the present invention; the device comprises:

and the image acquisition unit 210 is adapted to start modification and acquire a grid map of the current scene and a CAD (computer aided design) drawing of the current scene when the current scene at least comprises a part of artificial environment.

The embodiment of the invention acquires the grid map and the corresponding CAD graph which are formed according to the acquisition of the laser sensor, corrects the grid map by means of the CAD graph in the indoor scene, and aims to optimize the artificial environment part in the grid map by referring to the CAD graph.

And an image alignment unit 220 adapted to align the grid map with the CAD drawing based on an image matching method of the feature points.

In the case of a CAD map of an indoor environment and a grid map constructed by laser SLAM, dimensions and directions may be inconsistent, and at this time, alignment needs to be performed by an image matching method based on pixel-level feature points.

The mapping unit 230 is adapted to identify a connected domain in the grid map, and determine a mapping domain corresponding to the connected domain in the aligned CAD drawing according to the mapping relationship.

The connected domain analysis is to analyze the connected domain of the grid map and determine the area that the robot can reach, and the connected domain mapping is that after the images are aligned, the CAD drawing and the grid map are already pictures with corresponding sizes and directions, and then the connected domain can be mapped to the area in the CAD drawing.

And the feature extraction unit 240 is adapted to extract high-level features indicating a certain geometric shape in the CAD drawing according to the mapping domain.

There are a large number of high-level features in indoor scenes, such as lines, curves, circles, etc. The invention performs high-level feature extraction and mapping on the mapped CAD graph so as to correct the grid map later.

And a map correction unit 250 adapted to map the extracted high-level features in a grid map and correct the grid map.

And fitting and correcting the high-level features in the grid map. Firstly, linear regression is carried out on the geometry corresponding to the feature set, and a geometric figure function is obtained. Because the geometric shapes in the grid map have a certain width, at this time, the corresponding width needs to be obtained through rendering and other manners so as to update the grid map.

In one embodiment, the image alignment unit 210 is adapted to: respectively extracting ORB characteristic points from the CAD graph and the grid map, wherein the ORB characteristic points comprise key pixel points and descriptors of the key pixel points are calculated; determining matched feature point pairs through the descriptors; determining the change values of the scale and the direction of the CAD graph through least square fitting according to the characteristic point pairs; and aligning the CAD graph with the grid map according to the change values of the scale and the direction.

In one embodiment, the high-level features include any one or more of: straight lines, broken lines, polygons, curves, ellipses, circles.

In one embodiment, the map correction unit 250 is adapted to: and mapping the high-level features in the CAD map into a grid map according to the corresponding positions and directions and the coordinate transformation relation.

In one embodiment, the map correction unit 250 is adapted to: determining a mathematical expression of the high-level feature according to pixel information of feature points in the high-level feature and a linear regression method; and adjusting the scale and the direction of the high-level features according to the mathematical expression to obtain the optimized high-level features.

To sum up, the grid map correction technical scheme disclosed by the invention comprises the following steps: when the current scene at least comprises part of artificial environment is judged, correction is started, and a grid map of the current scene and a Computer Aided Design (CAD) drawing of the current scene are obtained; aligning the grid map with the CAD graph by an image matching method based on the feature points; identifying a connected domain in the grid map, and determining a mapping domain corresponding to the connected domain in the aligned CAD graph according to the mapping relation; extracting high-level features indicating a certain geometric shape in the CAD graph according to the mapping domain; and mapping the extracted high-level features in a grid map, and correcting the grid map. Compared with a manual correction method, the correction scheme is more accurate and efficient, so that the accuracy of the grid map and the reliability of positioning navigation of robots, unmanned vehicles and the like are improved.

It should be noted that:

the algorithms and displays presented herein are not inherently related to any particular computer, virtual machine, or other apparatus. Various general purpose devices may be used with the teachings herein. The required structure for constructing such a device will be apparent from the description above. Moreover, the present invention is not directed to any particular programming language. It is appreciated that a variety of programming languages may be used to implement the teachings of the present invention as described herein, and any descriptions of specific languages are provided above to disclose the best mode of the invention.

In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the invention and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.

The various component embodiments of the invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It will be appreciated by those skilled in the art that a microprocessor or Digital Signal Processor (DSP) may be used in practice to implement some or all of the functions of some or all of the components in the grid map correction apparatus according to embodiments of the present invention. The present invention may also be embodied as apparatus or device programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present invention may be stored on computer-readable media or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.

For example, fig. 3 shows a schematic structural diagram of an electronic device according to an embodiment of the invention. The electronic device 300 comprises a processor 310 and a memory 320 arranged to store computer executable instructions (computer readable program code). The memory 320 may be an electronic memory such as a flash memory, an EEPROM (electrically erasable programmable read only memory), an EPROM, a hard disk, or a ROM. The memory 320 has a storage space 330 storing computer readable program code 331 for performing any of the method steps described above. For example, the storage space 330 for storing the computer readable program code may comprise respective computer readable program codes 331 for respectively implementing various steps in the above method. The computer readable program code 331 may be read from or written to one or more computer program products. These computer program products comprise a program code carrier such as a hard disk, a Compact Disc (CD), a memory card or a floppy disk. Such a computer program product is typically a computer-readable storage medium such as that of fig. 4. Fig. 4 shows a schematic structural diagram of a computer-readable storage medium according to an embodiment of the present invention. The computer readable storage medium 400 has stored thereon a computer readable program code 331 for performing the steps of the method according to the invention, readable by a processor 310 of the electronic device 300, which computer readable program code 331, when executed by the electronic device 300, causes the electronic device 300 to perform the steps of the method described above, in particular the computer readable program code 331 stored on the computer readable storage medium may perform the method shown in any of the embodiments described above. The computer readable program code 331 may be compressed in a suitable form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.

Claims

1. A grid map correction method in synchronous positioning and map construction is characterized by comprising the following steps:

aligning the grid map with the CAD graph based on an image matching method of the feature points;

identifying a connected domain in the grid map, and determining a mapping domain corresponding to the connected domain in the aligned CAD graph according to a mapping relation;

and mapping the extracted high-level features in the grid map, and correcting the grid map.

2. The method of claim 1, wherein the feature point based image matching method aligning the grid map with a CAD drawing comprises:

determining matched feature point pairs through the descriptors;

3. The method of claim 2, wherein the determining the matched pairs of feature points by the descriptor comprises:

and traversing key pixel points in the grid map and the CAD map, calculating Euclidean distances of key pixel point descriptors in the grid map and the CAD map according to bitwise and arithmetic, and determining a key pixel point pair with the minimum Euclidean distance value as a matched feature point pair.

4. The method of claim 2, wherein said determining the values of the change in the dimensions and orientation of the CAD drawing by least squares fitting from the pairs of feature points comprises:

acquiring the characteristic point pairs;

connecting two corresponding feature points in the CAD graph and the grid map respectively to determine a connecting line;

calculating the ratio of each corresponding connecting line;

5. The method of claim 1, wherein said mapping the extracted high-level features in the grid map comprises:

and mapping the high-level features in the CAD graph to the grid map according to the corresponding positions and directions and the coordinate transformation relation.

6. The method of claim 1, wherein the revising the grid map comprises:

determining a mathematical expression of the high-level feature according to the pixel information of the feature points in the high-level feature and a linear regression method;

7. The method of claim 1 or 6, wherein the revising the grid map further comprises:

adding pixel points in a preset neighborhood of the high-level feature to realize rendering of the high-level feature;

and fusing each rendered high-level feature with the adjacent feature of the high-level feature so as to update the grid map.

8. A device for correcting grid map in synchronous positioning and mapping, the device comprising:

the mapping unit is suitable for identifying the connected domain in the grid map and determining a mapping domain corresponding to the connected domain in the aligned CAD graph according to the mapping relation;

9. The apparatus of claim 8, wherein the image alignment unit is adapted to:

determining matched feature point pairs through the descriptors;

10. The apparatus of claim 8, wherein the high-level features include any one or more of: straight lines, broken lines, polygons, curves, ellipses, circles.