CN115965759B - Method for building digital modeling by using laser radar - Google Patents
Method for building digital modeling by using laser radar Download PDFInfo
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Abstract
The invention belongs to the technical field of data processing, and particularly relates to a method for building digital modeling by using a laser radar, which comprises the following steps: scanning an area containing a building through a laser radar, obtaining a three-dimensional point cloud on the area containing the building, obtaining a photographic image of the building in the area containing the building through an imaging device, and preprocessing the three-dimensional point cloud on the area containing the building; based on the preprocessed three-dimensional point cloud, and combining a plane layout diagram of a region containing a building, classifying the preprocessed three-dimensional point cloud, and simultaneously, independently carrying out digital modeling on the preprocessed three-dimensional point clouds of different categories; according to the photographic image of the building in the area containing the building, the building model corresponding to the preprocessed three-dimensional point clouds of different categories, which is obtained by separately carrying out digital modeling, is subjected to realistic processing.
Description
Technical Field
The invention belongs to the technical field of data processing, and particularly relates to a method for building digital modeling by using a laser radar.
Background
Along with the continuous development of computer technology, the demand for digital modeling of a building is increasing, the prior art generally scans the surface of the building through an aircraft-mounted laser radar to obtain a three-dimensional point cloud of the surface shape of the building, so that the digital modeling of the building is completed according to the three-dimensional point cloud, meanwhile, the prior art generally shoots a surface image of the building through an aircraft-mounted camera device, and further attaches the surface image of the building to the surface of the building to finally obtain a building model with strong reality, however, the prior art needs more manual participation in the digital modeling of the building, such as preprocessing of the three-dimensional point cloud, classification of the three-dimensional point cloud and the like, so that the digital modeling not only costs a large amount of labor cost, but also has lower efficiency.
Disclosure of Invention
According to the method, the three-dimensional point clouds of the surface shape of the building are obtained through the laser radar, the image of the surface of the building is obtained through the camera device, meanwhile, the three-dimensional point clouds are preprocessed to reduce the total number of three-dimensional coordinate points to be processed, so that the modeling efficiency is improved, the method for classifying the preprocessed three-dimensional point clouds is provided, the accuracy of the three-dimensional point clouds of different types is ensured, the building models of the three-dimensional point clouds of different types are subjected to realistic processing, and the sense of realism of the building models is enhanced.
In order to achieve the above object, the present invention provides a method for building digital modeling by using a laser radar, which mainly comprises the following steps:
step S1, scanning an area containing a building through a laser radar to obtain a three-dimensional point cloud on the area containing the building, wherein the three-dimensional point cloud comprises three-dimensional coordinate points representing the surface shape of the building in the area containing the building, acquiring a photographic image of the building in the area containing the building through an imaging device, and preprocessing the three-dimensional point cloud on the area containing the building;
s2, classifying the preprocessed three-dimensional point clouds based on the preprocessed three-dimensional point clouds and combining a plane layout diagram of a region containing a building, and simultaneously carrying out digital modeling on the preprocessed three-dimensional point clouds of different categories;
and S3, performing vivid processing on building models corresponding to the preprocessed three-dimensional point clouds of different categories, which are obtained by performing digital modeling alone, according to the photographic images of the buildings in the area containing the buildings.
As a preferred technical solution of the present invention, the preprocessing is performed on the three-dimensional point cloud on the area containing the building, including the following steps:
step S11, calculating the total number of all three-dimensional coordinate points in the three-dimensional point cloud, setting the expected total number of all three-dimensional coordinate points in the preprocessed three-dimensional point cloud, and calculating a proportion value of the expected total number to the total number;
step S12, dividing the whole space into a first space and a second space which are equal in the whole space formed by the three-dimensional point cloud, so as to divide the three-dimensional point cloud into three-dimensional coordinate points belonging to the first space and three-dimensional coordinate points belonging to the second space;
step S13, respectively calculating products of the number of the three-dimensional coordinate points in the first space and the proportional value and products of the number of the three-dimensional coordinate points in the second space and the proportional value aiming at the three-dimensional coordinate points in the first space and the three-dimensional coordinate points in the second space, and judging whether the product value is smaller than or equal to a preset product threshold value;
and S14, randomly removing a part of three-dimensional coordinate points in the corresponding space when the product meets a preset product threshold value or less, stopping dividing the corresponding space, continuously dividing the corresponding space into a first space and a second space which are equal when the product does not meet the preset product threshold value or less, and repeatedly executing the step S13 and the step S14.
As a preferred embodiment of the present invention, the number of the part of the three-dimensional coordinate points randomly removed in the corresponding space is a result value obtained by subtracting the product of the number of all the three-dimensional coordinate points in the corresponding space and the proportional value from the number of all the three-dimensional coordinate points in the corresponding space.
As a preferable technical scheme of the invention, the three-dimensional point cloud after pretreatment is classified, and the method comprises the following steps:
step S21, aligning a graph in the plane layout diagram of an area containing a building with the preprocessed three-dimensional point cloud on a bottom plane of the preprocessed three-dimensional point cloud, and translating the graph upwards along a vertical upward normal direction of the bottom plane;
step S22, determining the highest three-dimensional coordinate point in the preprocessed three-dimensional point cloud in the graph, forming a top plane where the highest three-dimensional coordinate point is located and which is parallel to the bottom plane, dividing the three-dimensional coordinate points in the spatial range defined by the graph, the bottom plane and the top plane into the same category, and setting a category identifier for each three-dimensional coordinate point in the same category;
step S23, for all three-dimensional coordinate points with the category identifications in the preprocessed three-dimensional point cloud, sequentially calculating the distance between each three-dimensional coordinate point and other three-dimensional coordinate points, and correcting the category identifications of the other three-dimensional coordinate points by using the category identifications of each three-dimensional coordinate point when the distance is smaller than or equal to a preset distance threshold.
As a preferable technical scheme of the invention, the distance threshold is larger than the average value of the distances between two adjacent three-dimensional coordinate points in the preprocessed three-dimensional point cloud, and is smaller than the average value of the distances between two adjacent three-dimensional point clouds after preprocessing.
As a preferable technical scheme of the invention, the building model corresponding to the preprocessed three-dimensional point clouds of different categories, which is obtained by separately carrying out digital modeling, is subjected to realistic processing, and the method comprises the following steps:
step S31, extracting three-dimensional shapes of building models corresponding to different types of preprocessed three-dimensional point clouds, which are obtained by digital modeling alone, respectively performing image processing on the photographic images of the buildings in an area containing the buildings, and respectively extracting two-dimensional shapes of the photographic images;
step S32, respectively obtaining a first projection graph, a second projection graph and a third projection graph of the three-dimensional shape of the building model on an XOY coordinate plane, an XOZ coordinate plane and a ZOY coordinate plane;
step S33, based on a first projection graph of a building model, calculating the similarity of the two-dimensional shape of the first projection graph and the photographic image to obtain first similarity, turning the first projection graph of the building model left and right once, calculating the similarity of the two-dimensional shape of the first projection graph after turning the first projection graph left and right and the photographic image to obtain second similarity, and selecting a corresponding similarity which is larger than a similarity threshold value while being larger than the first similarity and the second similarity;
step S34, for the second projection pattern of the building model and the third projection pattern of the building model, respectively, the corresponding similarity of the second projection pattern of the building model and the corresponding similarity of the third projection pattern of the building model are obtained by the same method as in the step S33, respectively, and then a part of the photographic image corresponding to the largest corresponding similarity is attached to the surface of the building model in combination with the corresponding similarity of the first projection pattern of the building model.
The invention also provides a system for building digital modeling by using the laser radar, which comprises the following modules:
a preprocessing module for scanning an area containing a building by a laser radar, obtaining a three-dimensional point cloud on the area containing the building, wherein the three-dimensional point cloud comprises three-dimensional coordinate points representing the surface shape of the building in the area containing the building, obtaining a photographic image of the building in the area containing the building by an imaging device, and preprocessing the three-dimensional point cloud on the area containing the building;
the modeling module is used for carrying out classification processing on the preprocessed three-dimensional point clouds based on the preprocessed three-dimensional point clouds and combining a plane layout diagram of a region containing a building, and simultaneously carrying out digital modeling on the preprocessed three-dimensional point clouds of different categories to obtain a building model;
and the post-processing module is used for performing vivid processing on building models corresponding to the preprocessed three-dimensional point clouds of different categories, which are obtained by performing digital modeling alone, according to the photographic images of the buildings in the area containing the buildings.
Compared with the prior art, the invention has the following beneficial effects:
1. in the invention, firstly, a laser radar scans an area containing a building to obtain a three-dimensional point cloud on the area containing the building, a camera device obtains a photographic image of the building in the area containing the building, and the three-dimensional point cloud on the area containing the building is preprocessed; secondly, based on the preprocessed three-dimensional point cloud, and combining a plane layout diagram of a region containing a building, classifying the preprocessed three-dimensional point cloud, and simultaneously, independently carrying out digital modeling on the preprocessed three-dimensional point clouds of different categories; and finally, performing realistic processing on building models corresponding to the preprocessed three-dimensional point clouds of different categories, which are obtained by performing digital modeling alone, according to the photographic images of the buildings in the area containing the buildings.
2. The invention solves the problems that the prior art needs more manual participation when carrying out digital modeling of a building, not only causes the digital modeling to cost a large amount of labor cost, but also causes lower efficiency of the digital modeling.
Drawings
FIG. 1 is a flow chart of steps of a method for building digital modeling using lidar according to the present invention;
fig. 2 is a block diagram showing the construction of a system for digital modeling of a building using a lidar according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
It will be understood that the terms "first," "second," and the like, as used herein, may be used to describe various elements, but these elements are not limited by these terms unless otherwise specified. These terms are only used to distinguish one element from another element. For example, a first xx script may be referred to as a second xx script, and similarly, a second xx script may be referred to as a first xx script, without departing from the scope of the present application.
The invention provides a method for building digital modeling by using a laser radar, which is shown in fig. 1, and is mainly realized by executing the following steps:
step S1, scanning an area containing a building by a laser radar to obtain a three-dimensional point cloud on the area containing the building, wherein the three-dimensional point cloud comprises three-dimensional coordinate points representing the surface shape of the building in the area containing the building, acquiring a photographic image of the building in the area containing the building by an imaging device, and preprocessing the three-dimensional point cloud on the area containing the building;
s2, based on the preprocessed three-dimensional point cloud, combining a plane layout diagram of a region containing a building, classifying the preprocessed three-dimensional point cloud, and simultaneously performing digital modeling on the preprocessed three-dimensional point cloud of different types;
and S3, performing realistic processing on building models corresponding to the preprocessed three-dimensional point clouds of different categories, which are obtained by performing digital modeling alone, according to the photographic images of the buildings in the area containing the buildings.
Specifically, the inventor finds that in practice, in the prior art, when performing digital modeling of a building, manual participation is needed, for example, preprocessing three-dimensional point clouds, classifying three-dimensional point clouds, and the like, so that not only does the digital modeling cost a lot of labor cost, but also the efficiency of the digital modeling is low, and therefore, the invention provides the step S1 to the step S3. In the step S1, when a different building exists in the area including the building, a three-dimensional point cloud concerning the surface shape of the different building can be obtained when the area including the building is scanned by using the lidar, and the photographed image of the building in the area including the building is referred to as a surface image of the different building, and information such as the surface color of the building can be displayed, in the step S2, the planar layout of the area including the building is referred to as a projected image obtained by projecting the area including the building from directly above the area including the building, and the projected image can represent the layout structure of the different building on the ground.
Further, the preprocessing is performed on the three-dimensional point cloud on the area containing the building, and the method comprises the following steps:
step S11, calculating the total number of all three-dimensional coordinate points in the three-dimensional point cloud, setting the expected total number of all three-dimensional coordinate points in the preprocessed three-dimensional point cloud, and calculating the proportion value of the expected total number to the total number;
step S12, dividing the whole space into a first space and a second space which are equal in the whole space formed by the three-dimensional point cloud, so as to divide the three-dimensional point cloud into three-dimensional coordinate points belonging to the first space and three-dimensional coordinate points belonging to the second space;
step S13, respectively calculating products of the number of the three-dimensional coordinate points in the first space and the proportion value and products of the number of the three-dimensional coordinate points in the second space and the proportion value aiming at the three-dimensional coordinate points belonging to the first space and the three-dimensional coordinate points belonging to the second space, and judging whether the product value is smaller than or equal to a preset product threshold value;
and S14, randomly removing a part of three-dimensional coordinate points in the corresponding space when the product meets a preset product threshold value or less, stopping dividing the corresponding space, continuously dividing the corresponding space into a first space and a second space which are equal when the product does not meet the preset product threshold value or less, and repeatedly executing the step S13 and the step S14.
Specifically, since the total number of three-dimensional coordinate points in the three-dimensional point cloud obtained by the laser radar can be very large, the amount of data to be processed in performing the digital modeling can be very large, in order to improve the overall efficiency of the digital modeling, a part of the three-dimensional coordinate points should be deleted from the massive three-dimensional coordinate points while the overall characteristics of the original three-dimensional coordinate points can be maintained, the above-mentioned step S11 to the above-mentioned step S14 can achieve the object, firstly, the total number of all three-dimensional coordinate points in the three-dimensional point cloud is counted, and further, the desired total number of all three-dimensional coordinate points in the desired three-dimensional point cloud after the preprocessing can be artificially set, and meanwhile, the desired total number is divided by the total number to obtain a proportional value, which is used in deleting the three-dimensional coordinate points, and secondly, in the whole space constituted by the three-dimensional point cloud, equally dividing the whole space into two parts, namely a first space and a second space, dividing the three-dimensional coordinate points in the three-dimensional point cloud into corresponding two parts, calculating the product of the number of the three-dimensional coordinate points in the first space and the proportional value again, calculating the product of the number of the three-dimensional coordinate points in the second space and the proportional value, judging the size relation between the two product and the product threshold value respectively, randomly deleting a certain number of three-dimensional coordinate points in the corresponding space when the product is smaller than or equal to the product threshold value, otherwise, continuing equally dividing the corresponding space into two parts, repeating the same subsequent method as the content, for example, if the product of the first space is larger than the product threshold value, continuing equally dividing the first space into two parts to obtain the first space and the second space, and judging the size relation between the product of the first space and the second space and the product threshold value and executing the subsequent steps. The steps S11 to S14 can reduce the data amount to be processed in the digital modeling, and improve the overall efficiency of the digital modeling.
Further, the number of the part of the three-dimensional coordinate points randomly removed in the corresponding space is a result value obtained by subtracting the product of the number of all the three-dimensional coordinate points in the corresponding space and the above-mentioned proportional value from the number of all the three-dimensional coordinate points in the corresponding space.
Specifically, in the whole space formed by the three-dimensional point cloud obtained by the laser radar, the distribution densities of the three-dimensional coordinate points in different places in the whole space are different, when a certain number of three-dimensional coordinate points are deleted from the corresponding space by using the method from the step S11 to the step S14, the deleted number of the three-dimensional coordinate points is a result value obtained by subtracting the product of the number of the three-dimensional coordinate points in the corresponding space and the proportion value from the number of the three-dimensional coordinate points in the corresponding space, that is, for different corresponding spaces, the three-dimensional coordinate points with fixed proportion value therein are always deleted, so that the whole feature of the three-dimensional point cloud after the pretreatment is the same as the whole feature of the three-dimensional point cloud before the pretreatment, the distribution density of the three-dimensional coordinate points in the whole space formed by the three-dimensional point cloud before the pretreatment is still larger than other places, and the distribution density of the three-dimensional coordinate points in the whole space formed by the three-dimensional point cloud before the pretreatment is still smaller than other places.
Further, the classification processing is performed on the preprocessed three-dimensional point cloud, and the method comprises the following steps:
step S21, aligning the graph in the plane layout diagram of the area containing the building with the preprocessed three-dimensional point cloud on the bottom plane of the preprocessed three-dimensional point cloud, and upwards translating the graph along the vertical upward normal direction of the bottom plane;
step S22, determining the highest three-dimensional coordinate point in the preprocessed three-dimensional point cloud positioned in the graph, forming a top plane where the highest three-dimensional coordinate point is positioned and which is parallel to the bottom plane, dividing the three-dimensional coordinate points in a space range defined by the graph, the bottom plane and the top plane into the same category, and setting a category identifier for each three-dimensional coordinate point in the same category;
step S23, calculating distances between each three-dimensional coordinate point and other three-dimensional coordinate points in sequence for all three-dimensional coordinate points with the category identifications in the preprocessed three-dimensional point cloud, and correcting the category identifications of the other three-dimensional coordinate points by using the category identifications of each three-dimensional coordinate point when the distances are smaller than or equal to a preset distance threshold value.
Further, the distance threshold is larger than an average value of distances between two adjacent three-dimensional coordinate points in the preprocessed three-dimensional point cloud, and is smaller than an average value of distances between two adjacent different types of preprocessed three-dimensional point clouds. The distance between the preprocessed three-dimensional point clouds of two adjacent different categories can be obtained by calculating an average value of distances between two corresponding three-dimensional coordinate points in two parts of the two three-dimensional point clouds, which are close to each other, wherein the two corresponding three-dimensional coordinate points can be the closest two three-dimensional coordinate points.
Specifically, the inventor considers that in the prior art, when classifying three-dimensional point clouds, manual participation is generally needed, the three-dimensional point clouds are classified into different types by means of manual judgment, the three-dimensional point clouds of the different types respectively represent different buildings, a method for manually classifying the three-dimensional point clouds is low in efficiency, the accuracy of the three-dimensional point clouds of the different types is low, and for this technical problem, the above step S21 to the above step S23 are further proposed, firstly, different graphs in a plane layout diagram of an area including a building and the preprocessed three-dimensional point clouds are aligned on a bottom plane, wherein the plane layout diagram of the area including the building is a projection diagram obtained by projecting an area including the building from a position right above the area including the building, the projection diagram further includes different graphs, and the different graphs respectively correspond to the different buildings, the bottom plane is one coordinate plane in a three-dimensional coordinate system where the preprocessed three-dimensional point cloud is located, and can be an XOY coordinate plane, after the three-dimensional point cloud is aligned with different graphics, the different graphics are further vertically translated upwards, if the bottom plane is the XOY coordinate plane, the different graphics are translated along the positive direction of the Z axis, then in the preprocessed three-dimensional point cloud surrounded by the different graphics, the highest three-dimensional coordinate point is respectively determined, a top plane is respectively generated, the highest three-dimensional coordinate point is located on the top plane, the top plane and the bottom plane are parallel to each other, so that the three-dimensional coordinate points in the preprocessed three-dimensional point cloud surrounded by the bottom plane, the graphics and the top plane are regarded as belonging to a category, and a category identifier is simultaneously set for each three-dimensional coordinate point, finally, regarding three-dimensional coordinate points with category identification, considering that when two different buildings are staggered up and down, namely, the part of a lower building is blocked by an upper building, if the three-dimensional point clouds of the two buildings are classified by only relying on a plane layout diagram of an area containing the buildings, the category identification which is wrongly given to the three-dimensional coordinate points of the lower building exists, so that in order to solve the problem, the distances between the three-dimensional coordinate points with the category identification and other three-dimensional coordinate points are calculated respectively, and if the distances are less than or equal to a distance threshold value, the other three-dimensional coordinate points are judged to be the same category as the three-dimensional coordinate points. The above steps S21 to S23 can automatically perform classification processing on the three-dimensional point cloud, and ensure accuracy of the three-dimensional point clouds of different categories.
Further, performing realistic processing on building models corresponding to the preprocessed three-dimensional point clouds of different categories, which are obtained by separately performing digital modeling, wherein the method comprises the following steps:
step S31, extracting three-dimensional shapes of building models corresponding to different types of the preprocessed three-dimensional point clouds, which are obtained by digital modeling alone, respectively performing image processing on the photographic images of the buildings in the area containing the buildings, and respectively extracting two-dimensional shapes of the photographic images;
step S32, respectively obtaining a first projection graph, a second projection graph and a third projection graph of the three-dimensional shape of the building model on an XOY coordinate plane, an XOZ coordinate plane and a ZOY coordinate plane;
step S33, based on a first projection graph of a building model, calculating the similarity of the two-dimensional shape of the first projection graph and the photographic image to obtain first similarity, turning the first projection graph of the building model left and right once, calculating the similarity of the two-dimensional shape of the first projection graph after turning the first projection graph left and right and the photographic image to obtain second similarity, and selecting a corresponding similarity which is larger than a similarity threshold value while being larger from the first similarity and the second similarity;
step S34, for the second projection pattern of the building model and the third projection pattern of the building model, respectively, the corresponding similarity of the second projection pattern of the building model and the corresponding similarity of the third projection pattern of the building model are obtained by the same method as in the above step S33, respectively, and then, in combination with the corresponding similarity of the first projection pattern of the building model, a part of the photographic image corresponding to the largest corresponding similarity is attached to the surface of the building model.
Specifically, after obtaining the building models of different buildings respectively, in order to increase the realism of the building models, it is also necessary to perform a realistic process on the building models, in the above step S31, obtain three-dimensional shapes of the surfaces of the building models, which may be cubes, for example, and obtain different two-dimensional shapes from photographic images of the buildings in the area containing the buildings, in which a second process is performed on the photographic images, and different two-dimensional image contours corresponding to the photographic images of different portions are continuously extracted therefrom, that is, different two-dimensional shapes are corresponding to different buildings, in the above step S32, a first projection pattern on the XOY coordinate plane, the XOZ coordinate plane, a second projection pattern, and a third projection pattern on the ZOY coordinate plane are obtained respectively, the step S33 is implemented to convert the three-dimensional shapes into two-dimensional projection patterns, and in the above step S33, the first projection pattern and the second projection pattern are calculated, and the first and second projection pattern are also calculated by a method, and the similarity between the first and second projection pattern and the second projection pattern is obtained by a method, in which the first and second projection pattern is the same as the first and second projection pattern, and the second projection pattern is obtained by a second projection method, and the first and second projection pattern is the same as the first and has a second projection method, and has a larger similarity value and a second similarity value and a first projection image and a second projection image is obtained, from these three respective degrees of similarity, a portion of the photographic image corresponding to that largest respective degree of similarity is selected, and the portion of the photographic image is attached to the surface of the building model. The above steps S31 to S34 can improve the sense of realism of the building model.
Referring to fig. 2, the present invention further provides a system for performing building digital modeling by using a lidar, which includes a preprocessing module 100, a modeling module 200, and a post-processing module 300, for implementing a method for performing building digital modeling by using a lidar as described above, and specifically, the functions of each module are described as follows:
a preprocessing module 100 for scanning an area containing a building by a laser radar, obtaining a three-dimensional point cloud on the area containing the building, the three-dimensional point cloud including three-dimensional coordinate points representing a surface shape of the building in the area containing the building, and obtaining a photographic image of the building in the area containing the building by an imaging device, and further for preprocessing the three-dimensional point cloud on the area containing the building;
the modeling module 200 is configured to perform classification processing on the preprocessed three-dimensional point cloud based on the preprocessed three-dimensional point cloud and in combination with a planar layout of an area including a building, and separately perform digital modeling on the preprocessed three-dimensional point cloud of different types to obtain a building model;
the post-processing module 300 is configured to perform realistic processing on building models corresponding to different types of preprocessed three-dimensional point clouds obtained by separately performing digital modeling according to photographic images of buildings in an area including the building.
It should be understood that, although the steps in the flowcharts of the embodiments of the present invention are shown in order as indicated by the arrows, these steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in various embodiments may include multiple sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, nor do the order in which the sub-steps or stages are performed necessarily performed in sequence, but may be performed alternately or alternately with at least a portion of the sub-steps or stages of other steps or other steps.
Those skilled in the art will appreciate that implementing all or part of the above-described methods may be accomplished by way of computer programs, which may be stored on a non-transitory computer readable storage medium, and which, when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the various embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), memory bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
The technical features of the above embodiments may be arbitrarily combined, and for brevity, all of the possible combinations of the technical features of the above embodiments are not described, however, they should be considered as the scope of the description of the present specification as long as there is no contradiction between the combinations of the technical features.
The foregoing examples have been presented to illustrate only a few embodiments of the invention and are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (4)
1. A method for building digital modeling by using a lidar, comprising the steps of:
step S1, scanning an area containing a building through a laser radar to obtain a three-dimensional point cloud on the area containing the building, wherein the three-dimensional point cloud comprises three-dimensional coordinate points representing the surface shape of the building in the area containing the building, acquiring a photographic image of the building in the area containing the building through an imaging device, and preprocessing the three-dimensional point cloud on the area containing the building;
s2, classifying the preprocessed three-dimensional point clouds based on the preprocessed three-dimensional point clouds and combining a plane layout diagram of a region containing a building, and simultaneously carrying out digital modeling on the preprocessed three-dimensional point clouds of different categories;
s3, performing vivid processing on building models corresponding to the preprocessed three-dimensional point clouds of different categories, which are obtained by performing digital modeling alone according to the photographic images of the buildings in the area containing the buildings;
the preprocessing is performed on the three-dimensional point cloud on the area containing the building, and comprises the following steps:
step S11, calculating the total number of all three-dimensional coordinate points in the three-dimensional point cloud, setting the expected total number of all three-dimensional coordinate points in the preprocessed three-dimensional point cloud, and calculating a proportion value of the expected total number to the total number;
step S12, dividing the whole space into a first space and a second space which are equal in the whole space formed by the three-dimensional point cloud, so as to divide the three-dimensional point cloud into three-dimensional coordinate points belonging to the first space and three-dimensional coordinate points belonging to the second space;
step S13, respectively calculating products of the number of the three-dimensional coordinate points in the first space and the proportional value and products of the number of the three-dimensional coordinate points in the second space and the proportional value aiming at the three-dimensional coordinate points in the first space and the three-dimensional coordinate points in the second space, and judging whether the product value is smaller than or equal to a preset product threshold value;
step S14, randomly removing a part of three-dimensional coordinate points in the corresponding space when the product meets a preset product threshold value or less, stopping dividing the corresponding space, continuously dividing the corresponding space into a first space and a second space which are equal when the product does not meet the preset product threshold value or less, and repeatedly executing the step S13 and the step S14;
classifying the preprocessed three-dimensional point cloud, wherein the classifying comprises the following steps of:
step S21, aligning a graph in the plane layout diagram of an area containing a building with the preprocessed three-dimensional point cloud on a bottom plane of the preprocessed three-dimensional point cloud, and translating the graph upwards along a vertical upward normal direction of the bottom plane;
step S22, determining the highest three-dimensional coordinate point in the preprocessed three-dimensional point cloud in the graph, forming a top plane where the highest three-dimensional coordinate point is located and which is parallel to the bottom plane, dividing the three-dimensional coordinate points in the spatial range defined by the graph, the bottom plane and the top plane into the same category, and setting a category identifier for each three-dimensional coordinate point in the same category;
step S23, calculating distances between each three-dimensional coordinate point and other three-dimensional coordinate points in sequence for all three-dimensional coordinate points with the category identifications in the preprocessed three-dimensional point cloud, and correcting the category identifications of the other three-dimensional coordinate points by using the category identifications of each three-dimensional coordinate point when the distances are smaller than or equal to a preset distance threshold;
performing realistic processing on building models corresponding to the preprocessed three-dimensional point clouds of different categories, which are obtained by performing digital modeling alone, wherein the realistic processing comprises the following steps:
step S31, extracting three-dimensional shapes of building models corresponding to different types of preprocessed three-dimensional point clouds, which are obtained by digital modeling alone, respectively performing image processing on the photographic images of the buildings in an area containing the buildings, and respectively extracting two-dimensional shapes of the photographic images;
step S32, respectively obtaining a first projection graph, a second projection graph and a third projection graph of the three-dimensional shape of the building model on an XOY coordinate plane, an XOZ coordinate plane and a ZOY coordinate plane;
step S33, based on a first projection graph of a building model, calculating the similarity of the two-dimensional shape of the first projection graph and the photographic image to obtain first similarity, turning the first projection graph of the building model left and right once, calculating the similarity of the two-dimensional shape of the first projection graph after turning the first projection graph left and right and the photographic image to obtain second similarity, and selecting a corresponding similarity which is larger than a similarity threshold value while being larger than the first similarity and the second similarity;
step S34, for the second projection pattern of the building model and the third projection pattern of the building model, respectively, the corresponding similarity of the second projection pattern of the building model and the corresponding similarity of the third projection pattern of the building model are obtained by the same method as in the step S33, respectively, and then a part of the photographic image corresponding to the largest corresponding similarity is attached to the surface of the building model in combination with the corresponding similarity of the first projection pattern of the building model.
2. A method for digitally modeling a building using lidar according to claim 1, wherein the number of a portion of the three-dimensional coordinate points randomly removed in the corresponding space is the result of subtracting the product of the number of all three-dimensional coordinate points in the corresponding space and the proportional value from the number of all three-dimensional coordinate points in the corresponding space.
3. A method of building digital modeling using lidar according to claim 1, wherein the distance threshold is greater than an average of distances between two adjacent three-dimensional coordinate points in the preprocessed three-dimensional point cloud, and is less than an average of distances between two adjacent different categories of the preprocessed three-dimensional point cloud.
4. A system for building digital modeling using lidar for implementing the method of any of claims 1-3, comprising the following modules:
a preprocessing module for scanning an area containing a building by a laser radar, obtaining a three-dimensional point cloud on the area containing the building, wherein the three-dimensional point cloud comprises three-dimensional coordinate points representing the surface shape of the building in the area containing the building, obtaining a photographic image of the building in the area containing the building by an imaging device, and preprocessing the three-dimensional point cloud on the area containing the building;
the modeling module is used for carrying out classification processing on the preprocessed three-dimensional point clouds based on the preprocessed three-dimensional point clouds and combining a plane layout diagram of a region containing a building, and simultaneously carrying out digital modeling on the preprocessed three-dimensional point clouds of different categories to obtain a building model;
and the post-processing module is used for performing vivid processing on building models corresponding to the preprocessed three-dimensional point clouds of different categories, which are obtained by performing digital modeling alone, according to the photographic images of the buildings in the area containing the buildings.
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