CN110990737A - LOD-based lightweight loading method for indoor scene of web end - Google Patents

LOD-based lightweight loading method for indoor scene of web end Download PDF

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CN110990737A
CN110990737A CN201911252294.6A CN201911252294A CN110990737A CN 110990737 A CN110990737 A CN 110990737A CN 201911252294 A CN201911252294 A CN 201911252294A CN 110990737 A CN110990737 A CN 110990737A
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lod
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陈旋
周海
李芳芳
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Jiangsu Aijia Household Products Co Ltd
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Abstract

The invention discloses a LOD-based lightweight loading method for scenes in a web end room, and relates to a scene rendering technology. The method comprises the following steps: partitioning the models to be loaded in the indoor scene, keeping the scene topological structure of each model unchanged, generating LOD scene model data of different levels by adopting a side collapse simplification method, and storing the LOD scene model data as temporary cache data in a cloud server; the client accesses the cloud server to request required indoor scene data, the server loads a data model corresponding to the LOD level, basic LOD level data and level conversion relation data are generated at the same time, and when a user needs to load other LOD level data, the basic model data are converted into the data of the required level through conversion relation locally. According to the invention, a client cache mechanism is adopted, local access cache data is directly called for loading and scene object switching, the loading speed is increased, and the interactive experience is improved.

Description

LOD-based lightweight loading method for indoor scene of web end
Technical Field
The invention relates to a scene rendering technology, in particular to a web end indoor scene lightweight loading method based on LOD.
Background
The web end for loading the existing indoor scene does not adopt LOD detail division, and the direct loading of the maximum detail model causes that a better network environment and a larger bandwidth requirement are generally required when the loading scene is accessed. Therefore, the user has a great limitation in accessing indoor scenes through the web end, and the loading access is not smooth due to the influence of the network transmission speed.
The existing scene LOD division basically adopts models with different detail degrees, switching is carried out among different LOD levels, intermediate transition states among adjacent LOD levels are not considered, a plurality of LOD level models stored in the same object have a large amount of data redundancy, and different requirements of different customers on the model details cannot be met.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a LOD-based lightweight loading method for a web end indoor scene, so as to solve the problems that the loading access is not smooth due to the fact that the web end loaded by the existing indoor scene is not divided by LOD details and the largest detail model is directly loaded, and the different requirements of different clients on the model details cannot be met due to the fact that the existing scene does not consider the intermediate transition state between adjacent LOD levels
In order to achieve the purpose of the invention, the invention adopts the technical scheme that:
an LOD-based lightweight loading method for indoor scenes of a web end comprises the following steps:
1) the client accesses the cloud server to request the required indoor scene data, and the server preprocesses the model to be loaded;
2) partitioning a model to be loaded in an indoor scene according to identification information in space region storage information in the indoor scene, establishing an affiliation relationship between the model and a space according to the position of a three-dimensional model object in the indoor scene in the three-dimensional space, classifying the models belonging to the same space region range, and establishing a space topological relationship;
3) each model keeps a scene topological structure unchanged, and LOD scene model data of different levels are generated by adopting a side collapse simplification method and are stored in a cloud server as temporary cache data;
4) the server side generates indoor scene data required by a client request, generates basic LOD level data and level conversion relation data at the same time, and converts the basic model data into data of a required level through conversion relation locally when a user needs to load other LOD level data.
Further, the hierarchy conversion relation data is collapse sequence and vertex data of collapse edges.
Further, the LOD hierarchy is sequentially LOD0 level, LOD1 level, and LOD2 level.
Further, LOD0 level is a basic mesh model that exhibits the visual geometry contour characteristics of the model with minimal vertex data and triangle patches.
Further, LOD1 level is to use 20% -50% of the data of the original model vertex data to reveal model information.
Further, LOD2 level is raw model data.
Further, the method for generating the LOD level data comprises the steps of generating an occlusion relation of the model object in a visual range by using a visual angle according to a stored topological relation between three-dimensional model objects in the indoor space region, judging a visual geometric characteristic of a visual part of the object according to the occlusion relation, selecting a triangular patch vertex data set of the visual part of the three-dimensional object, and generating the available LOD data of the model object by adopting an edge collapse method based on the visual geometric characteristic.
Has the advantages that: compared with the prior art, the method for loading and displaying the indoor scene at the web end uses the cloud server as a data storage carrier, uses the LOD level model to describe the detailed data characteristics of the model in the indoor scene at different visual angles and display views, and provides the method for loading and displaying the indoor scene at the web end. The method comprises the steps of performing superposition calculation through a subarea of an indoor scene and a current visual angle range to form a visual cutting area to access and load visual objects in the area, adopting a client cache mechanism, adopting a cache mechanism for data accessed by a user, directly calling local access cache data to load and switch scene objects, and automatically performing smooth transition between simplified and different LOD level data when the web end loads the scene data according to the fineness of a user-defined model, so that the loading speed is increased, and the interactive experience is improved.
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Fig. 1 is a schematic flow diagram of a method for lightweight loading of an LOD-based web-end indoor scene according to the present invention.
Detailed Description
The present invention is further illustrated by the following specific examples, which are not intended to be limiting.
Example 1
An LOD-based lightweight loading method for indoor scenes of a web end comprises the following steps:
the client accesses the cloud server to request the required indoor scene data, and the server preprocesses the data required to be loaded;
partitioning a model to be loaded in an indoor scene according to identification information in space region storage information in the indoor scene, establishing an affiliation relationship between the model and a space according to the position of a three-dimensional model object in the indoor scene in the three-dimensional space, classifying the models belonging to the same space region range, and establishing a space topological relationship; the spatial topological relationship between the objects is determined approximately from the bounding volume of the model.
And generating an occlusion relation of the model object in a visual range by using a visual angle according to the stored topological relation between the three-dimensional model objects in the indoor space region, judging the visual geometric characteristics of the visual part of the object according to the occlusion relation, selecting a triangular patch vertex data set of the visual part of the three-dimensional object, and generating available LOD data of the model object by adopting an edge collapse method based on the visual geometric characteristics. The vertex data set S of the three-dimensional object is cut according to the visual angle to obtain a visual data set Vs, and the triangular patch data formed by the vertices of the set Vs data is calculated according to the weight of the collapsed edge, namely
Figure BDA0002309376400000031
Wherein u and v represent the two end points of the edge,
f, n are triangular faces,
normal is the normal vector of the face,
tv is the set of all faces containing the v point,
tuv is a set of all surfaces including u point and v point, the side with the weight not larger than the set threshold is an effective collapse side, the collapse direction is u to v, the collapse weight fits the square difference of the slope at the curve where the u and v vertexes are located in the curve according to model data, if the square difference is larger than the threshold β, the side cannot be used as the effective collapse side, otherwise, the side can be used as the effective collapse side.
And simplifying the model data, and finishing the collapse calculation when the number of data top points in the collapse calculation result set meets the model precision required by the LOD hierarchy. In the collapse settlement, the collapse process between the levels, that is, the top of the collapse margin, the order of the collapse margin, and the like are stored as conversion data for smoothly switching between LOD model data of different levels.
The method comprises the steps that model LOD levels are divided, three levels are automatically simplified by a three-dimensional model in an indoor scene, in the method, three levels are given by default, one LOD0 level represents a basic grid model, and the visual shape information of the model is shown by the minimum vertex data and triangle patches. The LOD1 level shows model information with 20% -50% of the proportional data of the original model vertex data, and the LOD2 level represents the original model data without any simplification.
LOD0 level object data the dataset Vs generated by the perspective occlusion determination in the above steps, only requires a minimum of points to represent the visible geometry contour features of the model object according to LOD0 in the hierarchy defined herein. And (3) generating a fitting curve equation of the Vs by adopting a cubic Beizer curve equation, wherein the calculation formula is as follows: b isn(t)＝P0(1-t)3+3P1t(1-t)2+3P2t2(1-t)+P3t3In which P is0Representing the starting point of the fitted curve, P3Representing the end point of the fitted curve data, P1，P2Generating a middle fitting curve Btemp for the data middle point, wherein the three-dimensional object data set obtained in the data side collapse calculation of more than or equal to 1 and more than or equal to 0, generates a middle fitting curve Btemp according to the curve fitting method, and generates a middle fitting curve Btemp according to the similarity of simulation curves of Btemp and VsWhether the degree is less than a certain threshold value sigma, according to the characteristic point of the curve, the slope and the gradient of the starting point and the end point, and according to the average variance of the difference value of the slope and the gradient, when the value is less than sigma, the collapse processing is ended, and the collapse data set P is the data set of the required level LOD 0.
The LOD1 object data uses the ratio between the number of data vertices in the collapse calculation and the number of original models as the calculation termination marker.
When a client requests to access and load data, loading initial data under a default visual angle and view; when a user changes an observation visual angle or views in an interaction process, the client only needs to send the current changed visual angle or view to the server, and only the model and the visible part of the model in the viewing cone are subjected to data calculation and display according to viewing cone cutting and shielding calculation, so that the data amount in data processing and loading display is reduced, the calculation loading speed of a three-dimensional scene is increased, and the interaction efficiency is improved.
When the Web client browses the three-dimensional scene data for display and loading, the client only needs to have a browser environment supporting the loading and display of the three-dimensional scene of the Web client, and no requirements are made on other performances. The client can cache a small amount of information of the conversion relation between the basic LOD level data and the high-level LOD data in the three-dimensional indoor scene model and the basic LOD level data, and when the visual angle of the client changes and the network state is not stable, the client can switch between different LOD level data by using local cache data, so that better interactive experience is provided.
It is to be noted that the above-mentioned list is only a few specific embodiments of the present invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.

Claims (7)

1. An LOD-based lightweight loading method for indoor scenes at a web end is characterized by comprising the following steps:
1) the client accesses the cloud server to request the required indoor scene data, and the server preprocesses the model to be loaded;
2) partitioning a model to be loaded in an indoor scene according to identification information in space region storage information in the indoor scene, establishing an affiliation relationship between the model and a space according to the position of a three-dimensional model object in the indoor scene in the three-dimensional space, classifying the models belonging to the same space region range, and establishing a space topological relationship;
3) each model keeps a scene topological structure unchanged, and LOD scene model data of different levels are generated by adopting a side collapse simplification method and are stored in a cloud server as temporary cache data;
4) the server side generates indoor scene data required by a client request, generates basic LOD level data and level conversion relation data at the same time, and converts the basic model data into data of a required level through conversion relation locally when a user needs to load other LOD level data.
2. The LOD-based web end indoor scene lightweight loading method according to claim 1, wherein in the step 4), the hierarchy conversion relation data is collapse sequence and vertex data of collapse edges.
3. The LOD-based web-end indoor scene lightweight loading method according to claim 1, wherein the LOD levels are LOD0 level, LOD1 level and LOD2 level in sequence.
4. The LOD-based web-end indoor scene lightweight loading method according to claim 3, wherein LOD0 level is a basic mesh model, and visual geometric shape contour features of the model are presented with minimum vertex data and triangle patches.
5. The LOD-based web-end indoor scene lightweight loading method of claim 3, wherein LOD1 level is to present model information with 20% -50% of data of original model vertex data.
6. The LOD-based web-end indoor scene lightweight loading method according to claim 3, wherein LOD2 level is original model data.
7. The LOD-based web-end indoor scene lightweight loading method according to claim 1, wherein the LOD level data generation method is that according to a stored topological relation between three-dimensional model objects in an indoor space region, an occlusion relation of the model objects in a visual range is generated by using a visual angle, a visual geometric feature of a visual part of the object is judged according to the occlusion relation, a triangle patch vertex data set of the visual part of the three-dimensional object is selected, and an available LOD data of the model object is generated by adopting an edge collapse method based on the visual geometric feature.
CN201911252294.6A 2019-12-09 2019-12-09 LOD-based lightweight loading method for indoor scene of web end Withdrawn CN110990737A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116366827A (en) * 2023-01-13 2023-06-30 北京航空航天大学云南创新研究院 High-precision large-scene image processing and transmitting method and device facing web end

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116366827A (en) * 2023-01-13 2023-06-30 北京航空航天大学云南创新研究院 High-precision large-scene image processing and transmitting method and device facing web end
CN116366827B (en) * 2023-01-13 2024-02-06 北京航空航天大学云南创新研究院 High-precision large-scene image processing and transmitting method and device facing web end

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Application publication date: 20200410