CN116597059A - Quick rendering method and system for oblique photography 3MX format model - Google Patents

Abstract

The application discloses a quick rendering method and a system for a 3MX format model of oblique photography, wherein the method comprises the following steps: converting the JPG format texture in the target 3MX format model into a format which can be directly rendered by the GPU, and storing the length and the height of the parsed texture into a new 3MX file in the converted format; grid data in the target 3MX format model is obtained, whether left-right hand coordinate system conversion is required to be carried out by adjusting the sequence of the vertex and the triangular surface index is determined according to the coordinate system rule of the target rendering engine, and the adjusted vertex, the triangular surface index and the original UV coordinate are converted into byte data and stored in a new 3MX file; and reading the new 3MX file, transmitting the read data to the GPU for rendering, and completing the loading rendering of the 3MX file. The application reduces the decompression operation of a large amount of data of the CPU, and achieves the effect of improving the loading speed and the rendering frame rate of the 3MX format model.

Description

Quick rendering method and system for oblique photography 3MX format model

Technical Field

The application relates to the technical field of oblique photography 3MX format model loading processing, in particular to a method and a system for rapidly rendering an oblique photography 3MX format model.

Background

The 3MX format model (or 3MX file) includes two types of files within it, one being a main file in JSON format and the other being a subfolder/subfolder tree in binary format. The master file contains scene metadata, identified by a 3MX extension. Binary files contain geometric structures, belonging to the 3MXB (3 MX binary) type, the 3MXB file generally describes a unique three-dimensional textured pyramid grid. In the 3MX format model, LOD is also referred to, which is a shorthand for Levels of Detai l, meaning multiple levels of detail. The LOD technology is to determine the resource allocation of object rendering according to the position and importance of the nodes of the object model in the display environment, and reduce the number of planes and the detail of non-important objects, so as to obtain efficient rendering operation.

Currently, in the prior art for loading and rendering 3MX format models, as the viewing angle is zoomed in, the higher the model LOD level of the 3MX format model is loaded, the lower the corresponding frame rate is, the longer the loading time is, resulting in serious delay of loading the display screen. The bottleneck cause of this problem is that parsing texture and mesh information in 3MX files requires a lot of hardware resources and a lot of computation. The textures in the 3MX file are stored in a JPG format, and the grid data including vertexes, triangular surface indexes and UV coordinates are stored after being processed by a compression algorithm of OpenCTM. In the loading rendering process, as the GPU cannot directly render JPG format textures, the texture loading interface used in the current prior art needs to firstly understand and press the textures into an original bitmap and then render. In addition, for the mesh data, the OpenCTM algorithm needs to be called to decompress, if the coordinate system of the target rendering engine is not the right-hand coordinate system, the vertex and the triangle index need to be reordered, and the parsing operations are completed by the CPU. As the LOD level is higher, which means that texture and grid information are more complex, the time for decompressing the data is longer, which finally results in excessive calculation pressure of the CPU and affects the loading speed of the 3MX format model. And because the operation capability of the GPU is very strong, the CPU submits data not timely, and the performance problems of picture delay, engine blocking and the like are caused. Therefore, there is a need for a processing method that increases the loading speed and rendering frame rate in the loading rendering process that faces the 3MX format model.

Disclosure of Invention

In view of the shortcomings of the prior art, it is an object of the present application to provide a fast rendering method for oblique photography 3MX format models, which can solve the problems mentioned in the background art;

it is a further object of the present application to provide a fast rendering system for oblique photography 3MX format models, which solves the above mentioned problems of the background art.

The technical scheme for realizing one of the purposes of the application is as follows: a fast rendering method of a oblique photography 3MX format model, comprising the steps of:

step 1: converting the JPG format texture in the target 3MX format model into a format which can be directly rendered by the GPU, and storing the length and the height of the parsed texture into a new 3MX file in the converted format;

step 2: obtaining grid data in the target 3MX format model, wherein the grid data comprises vertexes, triangular indexes and UV coordinates, adjusting the sequence of the vertexes and the triangular indexes, converting a right-hand coordinate system into a target rendering engine coordinate system, if the right-hand coordinate system is the right-hand coordinate system, the conversion is not needed, then converting the vertexes, the triangular indexes and the original UV coordinates after the sequence adjustment into byte data, and storing the byte data into a new 3MX file;

step 3: and reading the new 3MX file, transmitting the read data to the GPU for rendering, and completing the loading rendering of the 3MX file.

Further, the specific implementation of the step 1 includes:

analyzing the JPG format texture in the target 3MX format model by adopting a picture decompression algorithm to obtain original bitmap data, converting the original bitmap data into a format which can be directly rendered by a GPU, analyzing and obtaining the length and the height of the texture from the original bitmap data to obtain the length and the height of the texture, and storing the obtained length and the height of the texture into a new 3MX file in the converted format.

Further, in the step 1,

the format in which the GPU may render directly is the ETC1 format.

Further, in step 1, the new 3MX file is consistent with the LOD relationship structure of the target 3MX format model with respect to the LOD relationship structure.

Further, in the step 1, the conversion of the original bitmap data into a format that can be directly rendered by the GPU and the parsing of the original bitmap data to obtain the length and the height of the texture are completed synchronously,

or converting the original bitmap data into a format which can be directly rendered by the GPU and analyzing and acquiring the length and the height of the texture from the original bitmap data.

Further, converting the original bitmap data into a format that can be directly rendered by the GPU and analyzing the original bitmap data to obtain the length and the height of the texture are sequentially completed, which specifically means that the format conversion is completed first and then the length and the height of the texture are obtained, or the length and the height of the texture are obtained first and then the format conversion is completed.

Further, the specific implementation of the step 2 includes:

determining whether to adjust the vertex and triangle index according to the coordinate system rule of the rendering engine so as to convert the coordinate system of the rendering engine from a right-hand coordinate system, analyzing grid data in the target 3MX format model by adopting a decompression algorithm to obtain the vertex and triangle index of the grid, traversing the vertex and triangle index according to the coordinate format requirement of the rendering engine, adjusting the sequence of the vertex and triangle index, converting the vertex, triangle index and original UV coordinate after the sequence adjustment into byte data, and storing the byte data into a new 3MX file; if the rendering engine is the right hand coordinate system, the original vertex, triangle index and UV coordinates can be directly stored into the new 3MX file.

Further, the specific implementation of the step 3 includes:

step 31: the length and height of the texture and the texture data in ETC1 format are read from the 3MX file, the data are submitted to the GPU by using the rendering interface provided by the Unity3d engine, the GPU directly renders the texture,

step 32: and reading the array of the vertexes, the triangular indexes and the UV coordinates of the grids in the new 3MX file byte by byte, submitting the read array data to the GPU through an interface provided by the Unity3d engine, and rendering the grids by the GPU, thereby completing loading and rendering the 3MX file.

Further, the execution sequence of the step 31 and the step 32 is performed according to the sequence of the texture and the grid stored in the current 3MX file.

The second technical scheme for realizing the purpose of the application is as follows: a fast rendering system for oblique photography 3MX format models, comprising,

a texture processing module for analyzing texture data of the target 3MX format model, converting the JPG format texture of the target 3MX format model into a format which can be directly rendered by the GPU, acquiring the length and the height of the texture in the target 3MX format model, storing the converted texture format, the length and the height of the texture into a new 3MX file,

wherein the new 3MX file has a consistency with respect to LOD relationship structure with the LOD relationship structure of the target 3MX format model;

the grid data processing module is used for analyzing grid data in the target 3MX format model through a decompression algorithm to obtain vertexes, triangular indexes and UV coordinates of the grid, traversing the vertexes, the triangular indexes and the UV coordinates according to the coordinate format requirement of a used rendering engine, adjusting the sequence of the vertexes and the triangular indexes, if the rendering engine is the right-hand coordinate system, the rendering engine does not need to be adjusted, and then converting the vertexes, the triangular indexes and the original UV coordinates after the sequence adjustment into byte data and storing the byte data into a new 3MX file;

the data synchronous transfer module is used for reading data in the new 3MX file, the read data comprise texture data in the length and the height of textures and ETC1 format, and arrays of vertexes, triangular indexes and UV coordinates of grids, and the read data are sent to the GPU through an interface of the rendering engine, so that loading rendering is completed.

The beneficial effects of the application are as follows: according to the application, the 3MX format model of oblique photography is firstly subjected to texture and grid processing, and then a new 3MX format data is directly output, so that decompression on a CPU is avoided, the new 3MX format data can be directly transmitted to a GPU for rendering, a large amount of data decompression operation of the CPU is reduced, and the effects of improving the loading speed and rendering frame rate of the 3MX format model are achieved.

Drawings

FIG. 1 is a schematic flow chart of the present application;

FIG. 2 is a schematic diagram showing a comparison of a new 3MX file obtained by processing a target 3MX file in the above steps.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the following detailed description of specific embodiments of the present application is given with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the matters related to the present application are shown in the accompanying drawings. Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart depicts operations (or steps) as a sequential process, many of the operations can be performed in parallel, concurrently, or at the same time. Furthermore, the order of the operations may be rearranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figures. The processes may correspond to methods, functions, procedures, subroutines, and the like.

Example 1

As shown in fig. 1 and 2, a fast rendering method of a oblique photography 3MX format model includes the steps of:

step 1: and resolving JPG format textures in the target 3MX format model (namely the target 3MX file) by adopting a picture decompression algorithm to obtain original bitmap data, and then converting the original bitmap data into a format which can be directly rendered by the GPU. And the length and the height of the texture are also obtained from the original bitmap data in a parsing way, so that the length and the height of the texture are obtained. And stores the resulting texture length and height in the converted format to a new 3MX file.

In this step, the texture in the 3MX file is a JPG format texture, and the original bitmap data may be obtained by parsing the texture by using a picture decompression algorithm, for example, parsing the original bitmap data into a bmp format. The image decompression algorithm is not limited to an algorithm dedicated to image decompression, and may be applied to a decompression algorithm for decompressing an image. The obtained original bitmap data occupies a larger memory, so that a format conversion algorithm is also needed to convert the original bitmap data into a format which can be directly rendered by a GPU, for example, into texture data in ETC1 format, and the GPU can directly render the texture data in ETC1 format.

Wherein the new 3MX file is unchanged in relation to the LOD relationship structure, i.e. the LOD relationship structure is the same as the target 3MX format model, except for the texture and mesh data.

In an alternative embodiment, the converting of the original bitmap data into a format that can be directly rendered by the GPU and the parsing of the original bitmap data to obtain the length and the height of the texture, that is, the converting of the format and the obtaining of the length and the height of the texture are performed in parallel and synchronously. Or converting the original bitmap data into a format which can be directly rendered by the GPU and analyzing and acquiring the length and the height of the texture from the original bitmap data. For example, format conversion is completed first, then the length and height of the texture are acquired, or the length and height of the texture are acquired first, then format conversion is completed.

Step 2: and analyzing the grid data in the target 3MX format model by adopting a decompression algorithm to obtain the vertexes, the triangular indexes and the UV coordinates of the grid. Wherein, the vertex, triangle index and UV coordinate are generally expressed by arrays, so three array data of the grid are obtained. The decompression algorithm generally adopts an OpenCTM algorithm.

According to the coordinate system rule of the rendering engine, whether to adjust the vertex and triangle index so as to convert the right-hand coordinate system into the coordinate system of the rendering engine is determined.

In the 3MX format model, its coordinate system is based on the right-hand coordinate system, while the Unity3d engine is based on the left-hand coordinate system. Whereas vertex and triangle index in mesh data requires adjustment of coordinate system axial transformations according to the coordinate system of the rendering engine (e.g., unity3d engine). The UV coordinates have only XY axes, namely a two-dimensional plane coordinate system, so that the UV coordinates can be directly stored in a new 3MX file without adjustment.

More specifically, according to the coordinate system rule of the rendering engine, traversing the vertex and triangle index, adjusting the sequence of the vertex and triangle index, if the rendering engine is the right-hand coordinate system, not adjusting, then converting the vertex, triangle index and original UV coordinate after adjusting the sequence into byte data and storing the byte data in a new 3MX file.

Referring to fig. 2, fig. 2 is a schematic diagram showing a comparison of a new 3MX file obtained by processing a certain target 3MX file in the above steps, where the left half (i.e., the bottom picture) in fig. 2 is the original target 3MX file, and the right half (i.e., the top picture) is the new 3MX file. From fig. 2, the new 3MX file and the target 3MX file remain consistent in number and structure of files.

The steps 1 and 2 are all completed on the CPU, that is, the CPU completes the steps.

Step 3: and reading the new 3MX file, transmitting the read data to the GPU for rendering, and completing the loading rendering of the 3MX file.

In this step, GPU load rendering 3MX files are implemented using a Uni ty3d engine. Firstly, the length and the height of the texture and the texture data in ETC1 format are read from the 3MX file, the data are submitted to the GPU by using a rendering interface provided by a Unity3d engine, and the GPU directly renders the texture.

And reading the array of the vertexes, the triangular indexes and the UV coordinates of the grids in the new 3MX file byte by byte, submitting the read array data to the GPU through an interface provided by the Unity3d engine, and rendering the grids by the GPU, thereby completing loading and rendering the 3MX file.

Each independent 3MX file contains texture and grid data, and the execution sequence of the read texture data and the grid data is performed according to the sequence of the texture and the grid stored in the current 3MX file.

The comparison results of a small experiment made by the inventors using the scheme of this example and the scheme of the prior art are shown in the following table:

as can be seen from the table above, compared with the prior art, the loading speed and the rendering frame rate of the present embodiment are both improved, and the technical effect is better when the scheme of the present embodiment is improved compared with the prior art.

In the above steps, step 1 and step 2 may form a plug-in to complete preprocessing of the target 3MX format model, and after preprocessing, step 3 is performed and sent to the GPU for rendering.

According to the application, the 3MX format model of oblique photography is firstly subjected to texture and grid processing, and then a new 3MX format data is directly output, so that decompression on the GPU is avoided, the new 3MX format data can be directly transmitted to the GPU for rendering, a large amount of data decompression operation of the CPU is reduced, and the effects of improving the loading speed and rendering frame rate of the 3MX format model are achieved.

Example two

The application also relates to a fast rendering system for oblique photography 3MX format models, comprising,

the texture processing module is used for analyzing texture data of the target 3MX format model, converting the JPG format texture of the target 3MX format model into a format which can be directly rendered by the GPU, acquiring the length and the height of the texture in the target 3MX format model, and storing the converted texture format, the length and the height of the texture into a new 3MX file.

Wherein the new 3MX file is unchanged in relation to the LOD relationship structure, i.e. the LOD relationship structure is the same as the target 3MX format model, except for the texture and mesh data.

The grid data processing module is used for analyzing grid data in the target 3MX format model through a decompression algorithm to obtain vertexes, triangular indexes and UV coordinates of the grid, traversing the vertexes, the triangular indexes and the UV coordinates according to a coordinate system rule of a rendering engine, adjusting the sequence of the vertexes and the triangular indexes, if the rendering engine is the right-hand coordinate system, the rendering engine does not need to be adjusted, and then converting the vertexes, the triangular indexes and the original UV coordinates after the sequence adjustment into byte data and storing the byte data into a new 3MX file.

The data synchronous transfer module is used for reading data in the new 3MX file, the read data comprise texture data in the length and the height of textures and ETC1 format, and arrays of vertexes, triangular indexes and UV coordinates of grids, and the read data are sent to the GPU through an interface of the rendering engine, so that loading rendering is completed.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the application.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (10)

1. A method for fast rendering of a oblique photography 3MX format model, comprising the steps of:

step 1: converting the JPG format texture in the target 3MX format model into a format which can be directly rendered by the GPU, and storing the length and the height of the parsed texture into a new 3MX file in the converted format;

step 2: obtaining grid data in the target 3MX format model, wherein the grid data comprises vertexes, triangular indexes and UV coordinates, adjusting the sequence of the vertexes and the triangular indexes, converting a right-hand coordinate system into a target rendering engine coordinate system, if the right-hand coordinate system is the right-hand coordinate system, the conversion is not needed, then converting the vertexes, the triangular indexes and the original UV coordinates after the sequence adjustment into byte data, and storing the byte data into a new 3MX file;

step 3: and reading the new 3MX file, transmitting the read data to the GPU for rendering, and completing the loading rendering of the 3MX file.

2. The fast rendering method of oblique photography 3MX format models according to claim 1, characterized in that the specific implementation of step 1 comprises:

analyzing the JPG format texture in the target 3MX format model by adopting a picture decompression algorithm to obtain original bitmap data, converting the original bitmap data into a format which can be directly rendered by a GPU, analyzing and obtaining the length and the height of the texture from the original bitmap data to obtain the length and the height of the texture, and storing the obtained length and the height of the texture into a new 3MX file in the converted format.

3. The fast rendering method of a oblique photography 3MX format model according to claim 1 or 2, characterized in that in said step 1, the GPU directly renderable format is the ETC1 format.

4. The method of claim 1, wherein in step 1, the new 3MX file is consistent with the LOD relationship structure of the target 3MX format model with respect to the LOD relationship structure.

5. The method according to claim 1, wherein in the step 1, converting the original bitmap data into a format that the GPU can render directly and parsing the original bitmap data to obtain the length and height of the texture are completed simultaneously,

or converting the original bitmap data into a format which can be directly rendered by the GPU and analyzing and acquiring the length and the height of the texture from the original bitmap data.

6. The method according to claim 5, wherein the converting of the original bitmap data into a format that can be directly rendered by the GPU and the parsing of the original bitmap data to obtain the length and the height of the texture are sequentially completed, specifically, the format conversion is completed first and then the length and the height of the texture are obtained, or the length and the height of the texture are obtained first and then the format conversion is completed.

7. The fast rendering method of oblique photography 3MX format models according to claim 1, characterized in that the specific implementation of step 2 comprises:

determining whether to adjust the vertex and triangle index according to the coordinate system rule of the rendering engine so as to convert the coordinate system of the rendering engine from a right-hand coordinate system, analyzing grid data in the target 3MX format model by adopting a decompression algorithm to obtain the vertex and triangle index of the grid, traversing the vertex and triangle index according to the coordinate format requirement of the rendering engine, adjusting the sequence of the vertex and triangle index, converting the vertex, triangle index and original UV coordinate after the sequence adjustment into byte data, and storing the byte data into a new 3MX file; if the rendering engine is the right hand coordinate system, the original vertex, triangle index and UV coordinates can be directly stored into the new 3MX file.

8. The fast rendering method of oblique photography 3MX format models according to claim 1, characterized in that the specific implementation of step 3 comprises:

step 31: the length and height of the texture and the texture data in ETC1 format are read from the 3MX file, the data are submitted to the GPU by using the rendering interface provided by the Unity3d engine, the GPU directly renders the texture,

step 32: and reading the array of the vertexes, the triangular indexes and the UV coordinates of the grids in the new 3MX file byte by byte, submitting the read array data to the GPU through an interface provided by the Unity3d engine, and rendering the grids by the GPU, thereby completing loading and rendering the 3MX file.

9. The method of claim 8, wherein the steps 31 and 32 are performed in the order of the texture and mesh stored in the current 3MX file.

10. A fast rendering system for oblique photography 3MX format models, comprising,

a texture processing module for analyzing texture data of the target 3MX format model, converting the JPG format texture of the target 3MX format model into a format which can be directly rendered by the GPU, acquiring the length and the height of the texture in the target 3MX format model, storing the converted texture format, the length and the height of the texture into a new 3MX file,

wherein the new 3MX file has a consistency with respect to LOD relationship structure with the LOD relationship structure of the target 3MX format model;

the grid data processing module is used for analyzing grid data in the target 3MX format model through a decompression algorithm to obtain vertexes, triangular indexes and UV coordinates of the grid, traversing the vertexes, the triangular indexes and the UV coordinates according to the coordinate format requirement of a used rendering engine, adjusting the sequence of the vertexes and the triangular indexes, if the rendering engine is the right-hand coordinate system, the rendering engine does not need to be adjusted, and then converting the vertexes, the triangular indexes and the original UV coordinates after the sequence adjustment into byte data and storing the byte data into a new 3MX file;

the data synchronous transfer module is used for reading data in the new 3MX file, the read data comprise texture data in the length and the height of textures and ETC1 format, and arrays of vertexes, triangular indexes and UV coordinates of grids, and the read data are sent to the GPU through an interface of the rendering engine, so that loading rendering is completed.