Point cloud visualization device, point cloud visualization program, and point cloud visualization method

Abstract

A point group visualization device 1 compresses point group data representing space positions as point groups by using an octree structure in which each of the point groups is a node, acquires structure information corresponding to a node selected by a user, from point group compressed data hierarchically representing the nodes corresponding to the point groups, and hierarchically displays, on a display device, the structure of the point groups in the point group compressed data by sequentially executing, for the structure information of the node selected for each hierarchy layer, an operation of decoding the structure information.

Description

Technical Field

[0001] The disclosed technology relates to a point cloud visualization device, a point cloud visualization program, and a point cloud visualization method for point cloud compressed data.

Background Art

[0002] Due to the remarkable development of recent ICT (Information and Communication Technology) technologies, research on systems that integrate the physical space and the cyber space, such as collecting IoT (Internet of Things) data from various things in the physical space and analyzing the state of the physical space, has been actively conducted.

[0003] For example, research has been conducted to digitize the positions in the physical space using a measuring instrument such as LiDAR (Light Detection And Ranging) and construct them in the cyber space for use in maintaining and managing social infrastructure.

[0004] The positions in the physical space constructed in the cyber space are represented by three-dimensional point cloud data measured by a measuring instrument, and as the range of the physical space to be measured becomes wider, the data size of the point cloud data becomes larger. Therefore, it is necessary to compress the point cloud data in order to accumulate and utilize the point cloud data of a wide-area city.

[0005] Various methods exist for compressing point cloud data, but for example, point cloud data compression compliant with G-PCC (Geometry based Point Cloud Compression), a point cloud coding technology that is being promoted as a standard by MPEG (Motion Picture Experts Group), is often used (MPEG G-PCC codec description, <https: / / mpeg.chiariglione.org / standards / mpeg-i / geometry-based-point-cloud-compression / g-pcc-codec-description-v2> (See reference). As shown in Figure 11, G-PCC can compress the data size of the point cloud data to up to 1 / 10 of the original size by hierarchically dividing the space and representing the spatial location of the point cloud using an octave tree structure.

[0006] Visualization tools are used to visualize the compressed point cloud data (for example, CloudCompare).<https: / / www.danielgm.net / cc / > reference). [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, because the data size of compressed point cloud data is enormous, conventional visualization tools that attempt to decode the compressed point cloud data from the top layer to the bottom layer in one go take a long time to decode. Consequently, the long delay between instructing the visualization of the point cloud structure and the display of the structure causes problems that stress the user. In addition, conventional visualization tools require a fast CPU (Central Processing Unit) and a large amount of memory to decode compressed point cloud data, which limits the types of computers that can be used to visualize compressed point cloud data.

[0008] The disclosed technology was developed in view of the above points, and aims to provide a point cloud visualization device, a point cloud visualization program, and a point cloud visualization method that can shorten the time required to visualize the structure of a point cloud compared to the case where the structure of a point cloud is visualized after decoding from the top layer to the bottom layer of point cloud compression data having a hierarchical structure. [Means for solving the problem]

[0009] The point cloud visualization device according to the first aspect of this disclosure compresses point cloud data, which represents spatial positions as point clouds, using an octave tree structure in which each point cloud is a node, and from the compressed point cloud data in which each node corresponding to the point cloud is hierarchically represented, Starting from the top node Nodes selected by the user Nodes at each level up to A structural acquisition unit that acquires corresponding structural information, The operation of decoding the aforementioned structural information is performed as follows: From the aforementioned top node toward the node selected by the user Each level order Next, by having the structure acquisition unit perform the following: From the aforementioned top node to the child node located one level below the node selected by the user The system includes a control unit that controls the hierarchical display of the point cloud structure in the compressed point cloud data on a display device.

[0010] The point cloud visualization program according to a second aspect of this disclosure causes a computer to function as a component of a point cloud visualization device.

[0011] A point cloud visualization method according to a third aspect of this disclosure is a point cloud visualization method in a point cloud visualization apparatus including a structure acquisition unit, a control unit, and a reception unit, wherein the reception unit receives instructions from a user for compressed point cloud data in which spatial positions are represented as point clouds, using an octave tree structure in which each point cloud is a node, and each node corresponding to the point cloud is represented hierarchically, and the structure acquisition unit From the aforementioned point cloud compression data, starting from the top node Node selected by the above instruction Nodes at each level up to The acquisition step involves obtaining structural information corresponding to the acquisition step, and the control unit performs an operation to decode the acquired structural information. From the top node toward the node selected by the instruction Each level order Next, by having the structure acquisition unit perform the following: From the top node to the child node located one level below the node selected by the instructionA control step of hierarchically displaying the structure of the point cloud in the point cloud compression data on a display device is included.

Advantages of the Invention

[0012] According to the point cloud visualization device, the point cloud visualization program, and the point cloud visualization method of the present disclosure, compared with the case where the structure of the point cloud is visualized after decoding from the top layer to the bottom layer of the point cloud compression data having a hierarchical structure, there is an effect that the time required for visualizing the structure of the point cloud can be shortened.

Brief Description of the Drawings

[0013] [Figure 1] It is a diagram showing a functional configuration example of the point cloud visualization device. [Figure 2] It is a diagram showing an example of displaying the structure of the point cloud. [Figure 3] It is a diagram showing an example of a display dialog. [Figure 4] It is a diagram showing a main part configuration example of the electrical system of the point cloud visualization device. [Figure 5] It is a flowchart showing an example of the flow of the point cloud visualization process. [Figure 6] It is a diagram showing an example of hierarchical selection display. [Figure 7] It is a diagram showing another example of hierarchical selection display. [Figure 8] It is a diagram showing another example of hierarchical selection display. [Figure 9] It is a diagram showing an example of area selection display. [Figure 10] It is a diagram showing an example of zoom display. [Figure 11] It is a diagram showing the compression principle of point cloud compression data using G-PCC.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, an example of an embodiment according to the disclosed technology will be described while referring to the drawings. Note that the same reference numerals are given to the same or equivalent components, parts, and processes throughout the drawings, and redundant descriptions are omitted.

[0015] FIG. 1 is a diagram showing a functional configuration example of the point cloud visualization device 1 according to the embodiment. The point cloud visualization device 1 takes the point cloud compressed data 7 as an input, visualizes the structure of the point cloud represented by the point cloud compressed data 7, and displays it on the display device 19.

[0016] The point cloud compressed data 7 input to the point cloud visualization device 1 is, for example, compressed using an octree structure with each point cloud as a node 9 like G-PCC, and is the compressed data of the point cloud hierarchically representing each node 9 corresponding to the point cloud. That the node 9 is hierarchical means that, as shown in FIG. 11, the node 9 has a configuration based on the association with at least one of the upper-layer node 9 located above the node 9 and the lower-layer node 9 located below the node 9.

[0017] The point cloud visualization device 1 includes each functional part of a reception part 2, a structure acquisition part 3, a control part 4, and a display part 5, and a structure information database (DB) 6.

[0018] The reception part 2 receives a user's instruction regarding the display of the structure of the point cloud in the point cloud compressed data 7 displayed on the display device 19.

[0019] Based on the control of the control part 4, the structure acquisition part 3 acquires structure information corresponding to the user's instruction received by the reception part 2 from the point cloud compressed data 7. Specifically, the structure acquisition part 3 acquires the structure information corresponding to the node 9 selected by the user from the point cloud compressed data 7.

[0020] As already explained, each node 9, excluding the lowest-level node 9, has eight nodes 9 associated with it in the level below it, represented by an octave tree structure. The structural information corresponding to node 9 is information that shows the relationship between the selected node 9 and the nodes 9 in the level below it, starting from the selected node 9, and represents the structure of each node 9. For the sake of explanation, we will refer to the level below node 9 as the "lower layer of node 9".

[0021] Furthermore, the structure acquisition unit 3 decodes the structural information acquired from the point cloud compression data 7. This obtains the structure of the lower layer of the point cloud starting from the selected node 9. Hereafter, node 9, which is located at the root of the tree structure representing the point cloud compression data 7, will be referred to as "top node 9A," and the point cloud structure obtained by decoding the structural information corresponding to top node 9A will be referred to as "top node information." In addition, the point cloud structure obtained by decoding the structural information corresponding to nodes 9 other than top node 9A that constitute the tree structure representing the point cloud compression data 7 will be referred to as "child node information." The top node information and child node information together will be referred to as "node information."

[0022] The structure acquisition unit 3 stores the node information obtained by decoding in the structure information DB 6. The structure information DB 6 is an example of a database for storing node information.

[0023] The control unit 4 controls the processing of the reception unit 2, the structure acquisition unit 3, and the display unit 5. Further details will be explained later, but the control unit 4 controls the display of the point cloud structure in the compressed point cloud data 7 on the display device 19 by sequentially instructing the structure acquisition unit 3 to decode the structure information for the structure information of nodes 9 selected by the user for each layer. The point cloud structure is represented by the node information stored in the structure information DB 6. The point cloud structure represented by all the node information of the lowest layer in the compressed point cloud data 7 represents the point cloud data before compression.

[0024] The display unit 5, in accordance with the instructions of the control unit 4, displays the structure of the point cloud generated using the top node information and the node information of each node 9 selected by the user on the display device 19.

[0025] The display device 19 is a device that displays the structure of the point cloud indicated by the display unit 5, and for example, a liquid crystal display and an organic EL (Electro-Luminescence) display can be used. In this embodiment, the point cloud visualization device 1 and the display device 19 are described as separate devices, but the display device 19 may be built into the point cloud visualization device 1.

[0026] Figure 2 shows an example of the point cloud structure displayed on the display device 19. Figure 2 specifically shows an example of the point cloud structure at each level represented by the point cloud compression data 7.

[0027] The display unit 5 displays a display dialog 8 on the display device 19, which is equipped with a user interface (UI) for receiving instructions from the user specifying how the point cloud structure should be displayed on the display device 19. Instructions made by the user through the display dialog 8 are notified to the control unit 4 via the reception unit 2. The control unit 4 configures the point cloud structure in a display format according to the user's instructions and displays the point cloud structure represented in the specified display format on the display device 19 via the display unit 5.

[0028] Figure 3 shows an example of a display dialog 8. The display dialog 8 includes, for example, an information area 8A, a selection area 8B, and a control area 8C.

[0029] Information area 8A includes a UI for displaying the hierarchical structure of the point cloud compression data 7.

[0030] The designated area 8B includes a UI for specifying a node 9 from which to acquire structural information, based on the hierarchical structure of the point cloud compressed data 7 displayed in the information area 8A.

[0031] The control area 8C includes a UI for instructing the display device 19 on how to display the structure of the point cloud using node information obtained by decoding the structural information of each node 9 specified in the designated area 8B.

[0032] There are no restrictions on the content of the instructions for the display format of the point cloud structure. The point cloud visualization device 1 can perform displays such as asymptotic display, hierarchical selection display, region selection display, viewpoint movement display, and zoom display.

[0033] Asymptotic representation is a display mode that, when the user's instruction is a node selection instruction specifying any node 9 in the point cloud compression data 7, displays the structure of the point cloud at each level from the top node 9A to the specified node 9, according to the octave tree structure that constitutes the point cloud compression data 7, as shown in Figure 2. In other words, asymptotic representation is a display mode that displays the structure of the point cloud from the highest level to the specified level, and can be further understood as a display mode that gradually increases the resolution of the point cloud structure.

[0034] The hierarchical selection display is a display mode in which, when the user's instruction is a hierarchical selection instruction that specifies the hierarchy of the point cloud in the compressed point cloud data 7, only the structure of the point cloud in the specific hierarchy specified by the user is displayed on the display device 19.

[0035] The region selection display is a display mode in which, when the user's instruction is a region selection instruction that involves specifying a region of the point cloud in the compressed point cloud data 7, only the structure of the point cloud included in the region specified by the user is displayed on the display device 19.

[0036] The viewpoint shift display is a display mode in which, when the user's instruction is a change instruction to change the display direction of the point cloud structure in the point cloud compression data 7, the point cloud structure as viewed from the direction specified by the user is displayed on the display device 19.

[0037] Zoom display is a display mode in which, when the user's instruction is an enlargement or reduction instruction that includes specifying a point cloud area in the point cloud compression data 7, the structure of the point cloud included in the area specified by the user is enlarged or reduced and displayed on the display device 19.

[0038] The point cloud visualization device 1 shown in Figure 1 can be configured using, for example, a computer 10. Figure 4 shows an example of the main electrical system configuration of the point cloud visualization device 1 configured using the computer 10.

[0039] Computer 10 includes a CPU (Central Processing Unit) 11, which is an example of a processor responsible for executing each functional part of the point cloud visualization device 1 shown in Figure 1; a ROM (Read Only Memory) 12 that stores the startup program (Basic Input Output System: BIOS) that performs the startup process of computer 10; a RAM (Random Access Memory) 13 used as a temporary work area for the CPU 11; a non-volatile memory 14; and an input / output interface (I / O) 15. The CPU 11, ROM 12, RAM 13, non-volatile memory 14, and I / O 15 are connected to each other via a bus 16.

[0040] The non-volatile memory 14 is an example of a storage device that retains stored information even when the power supplied to the non-volatile memory 14 is cut off. For example, semiconductor memory is used, but a hard disk may also be used. Therefore, the non-volatile memory 14 stores, for example, a point cloud visualization program that makes the computer 10 function as a point cloud visualization device 1.

[0041] For example, a communication device 17, an input device 18, and a display device 19 are connected to I / O 15.

[0042] The communication device 17 is connected to a communication line (not shown) and is equipped with a communication protocol for data communication with an external device via the communication line.

[0043] The input device 18 is an example of a device that receives user instructions for the point cloud visualization device 1 and notifies the CPU 11, and includes, for example, a keyboard, mouse, touch panel, and pointing device.

[0044] Furthermore, when the point cloud visualization device 1 is remotely controlled from an external device, the point cloud visualization device 1 receives user instructions via the communication device 17 and transmits the information processed by the point cloud visualization device 1 to the external device via the communication device 17, and displays the information processed by the point cloud visualization device 1 on the display device 19 connected to the external device. Therefore, it is not always necessary to connect the input device 18 and the display device 19 to I / O 15.

[0045] Next, we will explain the operation of the point cloud visualization device 1 using the computer 10.

[0046] Figure 5 is a flowchart showing an example of the flow of point cloud visualization processing executed by the CPU 11 of the point cloud visualization device 1 when a visualization instruction for point cloud compressed data 7 is received from the display dialog 8.

[0047] The point cloud visualization program that defines the point cloud visualization process is pre-stored, for example, in the non-volatile memory 14 of the point cloud visualization device 1. The CPU 11 of the point cloud visualization device 1 reads the point cloud visualization program stored in the non-volatile memory 14 and executes the point cloud visualization process.

[0048] First, in step S10, the CPU 11 acquires the point cloud compression data 7 instructed by the user. The point cloud compression data 7 may be acquired from the non-volatile memory 14 or from an external device. If the instructed point cloud compression data 7 is acquired from an external device, the CPU 11 acquires the point cloud compression data 7 from the external device via the communication device 17.

[0049] Then, CPU 11 decodes the structural information corresponding to the top node 9A of the acquired point cloud compressed data 7 and obtains the top node information.

[0050] In step S20, the CPU 11 displays the structure of the point cloud generated using the node information to be displayed (in this case, the top node information) on the display device 19 along with the display dialog 8.

[0051] In response, the user operates the display dialog 8 while viewing the structure of the point cloud displayed on the display device 19 to give the desired instruction.

[0052] Therefore, in step S30, the CPU 11 determines whether or not it has received any instructions from the user. If it has not received any instructions from the user, it repeatedly executes the determination process in step S30 and waits for instructions from the user. If it has received instructions from the user, it proceeds to step S40.

[0053] In step S40, the CPU 11 determines whether the received instruction is a node selection instruction that selects any of the nodes 9. If the received instruction is a node selection instruction, the process proceeds to step S50.

[0054] In step S50, the CPU 11 decodes the structural information corresponding to node 9 specified by the node selection instruction and obtains the child node information of the specified node 9. The CPU 11 specifies the node information generated so far and the child node information obtained in step S50 as the node information to be displayed and proceeds to step S20. As already explained, the point cloud structure generated using the node information to be displayed is displayed on the display device 19 as a result of the processing in step S20. Therefore, the point cloud structure generated using each node information obtained each time the structural information corresponding to each node 9 from the top node 9A to the specified node 9 is decoded will be displayed on the display device 19.

[0055] In other words, the point cloud visualization device 1 does not decode the structural information of all nodes 9 in the compressed point cloud data 7 at once and display the structure of the entire point cloud on the display device 19, but rather performs an asymptotic display that shows the structure of the point cloud from the top node 9A to the specified node 9 on the display device 19 in a hierarchical manner.

[0056] On the other hand, if the determination process in step S40 determines that the received instruction is not a node selection instruction, the process proceeds to step S60.

[0057] In step S60, the CPU 11 determines whether the received instruction is a hierarchical selection instruction. If the received instruction is a hierarchical selection instruction, the process proceeds to step S70.

[0058] In step S70, the CPU 11 extracts node information at a specific hierarchy specified by the user from the node information obtained so far, specifies the extracted node information as the node information to be displayed, and proceeds to step S20. This enables a hierarchy selection display, which shows only the point cloud structure at the specific hierarchy specified by the user on the display device 19.

[0059] Figures 6, 7, and 8 show examples of hierarchical selection displays. As can be seen by comparing them with Figure 2, Figures 6, 7, and 8 only display the point cloud structure at the specified hierarchy.

[0060] On the other hand, if the determination process in step S60 determines that the received instruction is not a hierarchical selection instruction, the process proceeds to step S80.

[0061] In step S80, the CPU 11 determines whether the received instruction is an instruction to change the display direction. If the received instruction is an instruction to change the display direction, the process proceeds to step S90.

[0062] In step S90, the CPU 11 calculates the structure of the point cloud as viewed from the direction specified by the instruction to change the display direction, specifies the node information with the changed display direction as the node information to be displayed, and proceeds to step S20. As a result, a viewpoint shift display is performed, which displays the structure of the point cloud as viewed from the direction specified by the user on the display device 19.

[0063] On the other hand, if the determination process in step S80 determines that the received instruction is not an instruction to change the display direction, the process proceeds to step S100.

[0064] In step S100, the CPU 11 determines whether the received instruction is a region selection instruction. If the received instruction is a region selection instruction, the process proceeds to step S110.

[0065] In step S110, the CPU 11 extracts node information from the node information obtained so far that is included in the point cloud region specified by the region selection instruction, and specifies the extracted node information as the node information to be displayed before proceeding to step S20. As a result, region selection display is performed, which displays only the structure of the point cloud included in the region specified by the user on the display device 19. Figure 9 shows an example of region selection display.

[0066] On the other hand, if the determination process in step S100 determines that the received instruction is not an area selection instruction, the process proceeds to step S120.

[0067] In step S120, the CPU 11 determines whether the received instruction is a scaling instruction. If the received instruction is a scaling instruction, the process proceeds to step S130.

[0068] In step S130, the CPU 11 performs an enlargement or reduction operation on the node information included in the point cloud region specified by the enlargement or reduction instruction, and then proceeds to step S20, specifying the node information on which the enlargement or reduction operation was performed as the node information to be displayed. This enables zoom display, which enlarges or reduces the structure of the point cloud included in the region specified by the user and displays it on the display device 19. Note that the instruction to enlarge or reduce the structure of the point cloud is added to the enlargement or reduction instruction.

[0069] Figure 10 shows an example of a zoomed-in view of the point cloud structure. Figure 10 is a magnified view of the point cloud structure after the region selection display in Figure 9 has been performed.

[0070] On the other hand, if the determination process in step S120 determines that the received instruction is not a zoom instruction, the CPU 11 determines that the received instruction is a termination instruction and terminates the point cloud visualization process shown in Figure 5. Naturally, after the determination process in step S120 results in a negative determination, the CPU 11 may also determine whether or not the received instruction is a termination instruction. If the received instruction is a termination instruction, the CPU 11 terminates the point cloud visualization process; if the received instruction is neither a termination instruction nor a termination instruction, the CPU 11 considers the received instruction to be an invalid instruction and proceeds to step S30 to receive the next instruction.

[0071] Thus, the point cloud visualization device 1 does not decode the structural information of all nodes 9 in the compressed point cloud data 7 at once, but rather decodes it hierarchically according to the user's instructions and displays the resulting point cloud structure on the display device 19. Therefore, the time required to visualize the point cloud structure can be reduced compared to the case where the structural information contained in the compressed point cloud data 7 is decoded all at once.

[0072] Furthermore, the point cloud visualization device 1 allows the user to select the resolution of the point cloud structure. Therefore, the point cloud visualization device 1 can visualize the structure of a point cloud generated using, for example, only the structural information of the top layer of the compressed point cloud data 7, providing a useful function for users who only need to understand the general structure of the point cloud.

[0073] Although one embodiment of the point cloud visualization device 1 has been described above, the disclosed embodiment of the point cloud visualization device 1 is merely an example, and the embodiment of the point cloud visualization device 1 is not limited to the scope described in the embodiment. Various changes or improvements can be made to the embodiment without departing from the gist of this disclosure, and such changed or improved embodiments are also included in the technical scope of the disclosure. For example, the processing order of the point cloud visualization process shown in Figure 5 may be changed without departing from the gist of this disclosure.

[0074] Furthermore, this disclosure describes, as an example, a form in which point cloud visualization processing is implemented in software. However, processing equivalent to the flowchart shown in Figure 5 may also be implemented in hardware, for example, an ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), or PLD (Programmable Logic Device). In this case, processing speed can be increased compared to when point cloud visualization processing is implemented in software.

[0075] Thus, the CPU 11 of the point cloud visualization device 1 may be replaced with a dedicated processor specialized for specific processing, such as an ASIC, FPGA, PLD, GPU (Graphics Processing Unit), or FPU (Floating Point Unit).

[0076] The point cloud visualization device 1 can be implemented using a single CPU 11, or it may be executed using a combination of two or more processors of the same or different types, such as multiple CPUs 11, or a combination of a CPU 11 and an FPGA.

[0077] Furthermore, the point cloud visualization device 1 may be realized, for example, through the collaboration of processors located in physically distant locations connected via the Internet.

[0078] Furthermore, although the embodiment describes an example in which the point cloud visualization program is stored in the non-volatile memory 14 of the point cloud visualization device 1, the storage location of the point cloud visualization program is not limited to the non-volatile memory 14. The point cloud visualization program of this disclosure can also be provided in a form recorded on a storage medium readable by the computer 10. For example, the point cloud visualization program may be provided in a form recorded on an optical disc such as a CD-ROM (Compact Disk Read Only Memory) or DVD-ROM (Digital Versatile Disk Read Only Memory). Alternatively, the point cloud visualization program may be provided in a form recorded on a portable semiconductor memory such as a USB (Universal Serial Bus) memory or a memory card. ROM 12, non-volatile memory 14, CD-ROM, DVD-ROM, USB, and memory card are examples of non-transitory storage media.

[0079] Furthermore, the point cloud visualization device 1 may download a point cloud visualization program from an external device via the communication device 17 and store the downloaded point cloud visualization program in, for example, a non-volatile memory 14. In this case, the point cloud visualization device 1 reads the point cloud visualization program downloaded from the external device and executes the point cloud visualization process.

[0080] All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

[0081] With regard to the embodiments described above, the following additional information is disclosed.

[0082] (Additional note 1) Equipped with a processor, The aforementioned processor, Point cloud data, which represents spatial locations as a point cloud, is compressed using an octave tree structure where each point cloud is a node. From the compressed point cloud data, which hierarchically represents each node corresponding to a point cloud, structural information corresponding to the node selected by the user is obtained. The operation to decode the aforementioned structural information is performed sequentially for the structural information of nodes selected for each hierarchy, thereby controlling the display of the point cloud structure in the compressed point cloud data in a hierarchical manner on the display device. Point cloud visualization device 1.

[0083] (Additional note 2) A non-temporary storage medium that stores a program executable by a computer to perform point cloud visualization processing, The aforementioned point cloud visualization process, The process involves a point cloud data representation of spatial locations, which is compressed using an octave tree structure where each point cloud is a node. From this compressed point cloud data, which hierarchically represents each node corresponding to a point cloud, structural information corresponding to the node selected by the user is obtained. A control step that controls the display of the point cloud structure in the compressed point cloud data in a hierarchical manner on a display device by sequentially performing the operation of decoding the aforementioned structural information on the structural information of nodes selected for each hierarchy, Non-temporary storage media including [this].

Claims

1. A structure acquisition unit obtains structural information corresponding to the nodes in each level from the top node to the node selected by the user, from the compressed point cloud data, which represents spatial positions as a point cloud, by compressing the point cloud data using an octave tree structure in which each point cloud is a node, and representing each node corresponding to the point cloud in a hierarchical manner. A control unit controls the display of the point cloud structure in the compressed point cloud data, from the top node to the child node located one level below the node selected by the user, by sequentially executing the operation of decoding the aforementioned structural information on the structure acquisition unit in each hierarchy from the top node toward the node selected by the user, and by displaying the point cloud structure in the compressed point cloud data hierarchically on the display device. A point cloud visualization device equipped with the following features.

2. Each time the structural information is decoded, the control unit performs control to display the structure of the point cloud in the compressed point cloud data on the display device, using the decoding result of each structural information decoded for the compressed point cloud data. The point cloud visualization device according to claim 1.

3. The device includes a receiving unit that receives user instructions regarding the structure of the point cloud in the compressed point cloud data displayed on the display device, The control unit displays the structure of the point cloud in the compressed point cloud data on the display device in a display format according to the instructions. The point cloud visualization device according to claim 1.

4. If the instruction is a selection instruction specifying the hierarchy of the point cloud in the compressed point cloud data, the control unit controls the display device to display only the structure of the point cloud in the hierarchy specified by the instruction. If the instruction is a change instruction to change the display direction of the point cloud structure in the point cloud compression data, the control unit performs control to display the point cloud structure on the display device as viewed from the direction specified by the instruction. The point cloud visualization device according to claim 3.

5. If the instruction is a selection instruction that includes specifying a region of the point cloud in the point cloud compression data, the control unit performs control to display the structure of the point cloud included in the region specified by the instruction on the display device. If the instruction is an enlargement or reduction instruction that includes specifying a region of the point cloud in the point cloud compression data, the control unit performs control to enlarge or reduce the structure of the point cloud included in the region specified by the instruction and display it on the display device. The point cloud visualization device according to claim 3.

6. A point cloud visualization program for causing a computer to function as a component of the point cloud visualization apparatus described in any one of claims 1 to 5.

7. A point cloud visualization method in a point cloud visualization apparatus including a structure acquisition unit, a control unit, and a reception unit, The reception unit compresses point cloud data, which represents spatial positions as point clouds, using an octave tree structure with each point cloud as a node, and receives instructions from the user for the compressed point cloud data, which hierarchically represents each node corresponding to a point cloud. The structure acquisition unit performs an acquisition step of acquiring structural information corresponding to the nodes of each hierarchy from the top node to the node selected by the instruction, from the point cloud compression data, Control step: The control unit causes the structure acquisition unit to sequentially perform the operation of decoding the acquired structure information in each hierarchical level from the top node to the node selected by the instruction, thereby controlling the display of the point cloud structure in the compressed point cloud data from the top node to the child node located one level below the node selected by the instruction on the display device. A point cloud visualization method that includes this.

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