Method for Constructing Three-Dimensional Index of Island Landscape

Abstract

The present invention relates to a method for constructing a three-dimensional index of island landscapes. The method includes: measuring the three-dimensional information of the island surface to obtain the point cloud data and remote sensing image data of the island surface; constructing a digital surface model of the island and conducting three-dimensional and two-dimensional landscape classification of the island; constructing three types of three-dimensional indices for the island, namely, the basic landscape three-dimensional index, the three-dimensional vegetation index of the island, and the three-dimensional building impact index of the island, and using the two-dimensional landscape indices calculated by Fragstats for evaluation and verification. This method makes full use of the three-dimensional information of the point cloud data obtained by modern oblique photogrammetry, constructs a three-dimensional landscape index and evaluation system according to the characteristics of the impact of island vegetation and construction activities, and makes up for the deficiency of the traditional two-dimensional landscape index that cannot truly reflect the current situation of the island landscape due to the lack of three-dimensional information.

Description

Technical Field

[0001] The present invention relates to the technical field of landscape ecology, and particularly relates to a method for constructing a three-dimensional index of island landscapes. Background Art

[0002] The landscape index system (taking Fragstat as an example) that has been consistently used in the current academic community, and numerous indices at the patch, class, and landscape levels are all established on a two-dimensional scale. However, a lot of important ecological and human activity intensity information is highly correlated with its characteristics in the three-dimensional space (such as topography, features of ground objects, above-ground biomass, volume of artificial structures, etc.). Without the information of the third dimension, it is undoubtedly incomplete to study and evaluate the landscape integrity and connectivity of the ecosystem only from the two-dimensional plane scale.

[0003] However, current domestic and foreign research on landscape effects mostly focuses on aspects such as evolution and its driving force mechanism, and there are also many studies on coastal zones and coastal cities. However, there is a lack of research on the ecological effects and ecosystem services brought about by the landscape pattern evolution of island cities. As an independent ecosystem that lacks ecological flow connection with the outside world, island city forests are more sensitive to the urbanization process, and the ecological service functions they provide are also more vulnerable to the influence of landscape pattern effects. Therefore, quantitatively analyzing and evaluating the impact of island landscape pattern evolution on the ecological value of urban forests helps to analyze the problems arising in the land use of island cities from the root, and has guiding significance for formulating reasonable urban forest planning and environmental protection policies.

[0004] Especially in the ecological evaluation of islands, currently, most evaluation indicators are also constructed based on two-dimensional characteristics, and their deficiencies are as follows:

[0005] ① Islands are known for their undulating terrain that is surrounded by water and higher than sea level. Compared with three-dimensional information, two-dimensional information lacks elevation information, which also greatly reduces the evaluation effect of the currently constructed island ecological index in use.

[0006] ② The terrain of islands is complex and uneven, and it is closely affected by human activities. It is impossible to fully reflect important ecological and human activity intensity information only from the two-dimensional scale.

[0007] The existing urban three-dimensional landscape indicators currently cannot be fully applied to the landscape ecological evaluation in closed areas such as islands, and there is a lack of a three-dimensional ecological evaluation system for island areas. Summary of the Invention

[0008] The purpose of the present invention is to propose a three-dimensional ecological evaluation system for islands to more truly reflect the island ecological system in view of the deficiencies of the evaluation index system constructed by two-dimensional landscape indicators.

[0009] To solve the above problems, the present invention provides the following technical solutions:

[0010] A method for constructing a three-dimensional index of island landscapes, comprising the following steps:

[0011] Data acquisition step: Measure the three-dimensional information of the island surface to obtain the point cloud data and remote sensing image data of the island surface;

[0012] Point cloud data processing step: Filter the point cloud data within the research area, generate ground points, classify the point cloud data according to landscape types, and the landscape types include: buildings, low-height vegetation, medium-height vegetation, high-height vegetation, and roads; Extract elevation information and create three-dimensional landscape indicators;

[0013] Remote sensing data processing step: Process the remote sensing image data, perform radiometric calibration and atmospheric correction on the original data, and crop the data required for the research area; Classify the remote sensing data according to landscape types, and create two-dimensional landscape indicators based on Fragstats analysis;

[0014] The two-dimensional landscape indicators include: basic two-dimensional landscape indicators, and the basic landscape two-dimensional index includes one or a combination of the following indexes: patch density, landscape shape index, contagion index, largest patch index, Shannon diversity index, Shannon evenness index;

[0015] The three-dimensional landscape indicators include: basic landscape three-dimensional index, island three-dimensional vegetation index, and island three-dimensional building impact index. The basic landscape three-dimensional index includes one or a combination of the following indexes: three-dimensional patch density, three-dimensional landscape shape index, three-dimensional contagion index, three-dimensional largest patch index, and island diversity index;

[0016] Three-dimensional index evaluation step: Fit the basic landscape three-dimensional index with the basic landscape two-dimensional index to determine whether the trend shown by the three-dimensional index evaluation result is the same as the trend shown by the two-dimensional index evaluation result;

[0017] If so, determine that the evaluation of the basic landscape three-dimensional index is qualified; if not, return to the index creation stage. If so, determine that the evaluation of the basic landscape three-dimensional index is qualified; if not, return to the index creation stage, find the index with an obvious difference between the three-dimensional index calculation result and the two-dimensional index calculation result. If the volume is used to replace the area information in the two-dimensional formula in the original three-dimensional index creation formula, try to replace the area information in the two-dimensional formula with the surface area again and calculate the three-dimensional index; On the contrary, if the surface area is used to replace the area information in the two-dimensional formula in the original three-dimensional index creation formula, try to replace the area information in the two-dimensional formula with the volume again, re-calculate and evaluate the three-dimensional index, and re-participate in the trend comparison.

[0018] Analyze the island ecological environment by using the three-dimensional building index of the island, the three-dimensional vegetation index of the island, and the evaluated three-dimensional index of the basic landscape.

[0019] In some embodiments of the present invention, the calculation method of the three-dimensional patch density TPD includes:

[0020]

[0021] Wherein:

[0022] N i is the total number of patches in the i-th landscape type on the island. The number of patches is counted by drawing the contour lines of the point cloud, and the number of all closed contour lines is used as the total number of patches in the i-th landscape type;

[0023] V i is the total volume of the island landscape: calculated from the ground and the overall curved surface of the island based on the point cloud 2.5D volume algorithm.

[0024] In some embodiments of the present invention, the calculation method of the three-dimensional landscape shape index includes:

[0025]

[0026] Wherein: E is the total length of all patch contour lines in the i-th landscape type, A surface is the total surface area of the i-th landscape, A volume is the total volume of the i-th landscape.

[0027] In some embodiments of the present invention, the calculation method of the three-dimensional contagion includes:

[0028]

[0029] Wherein:

[0030] P i represents the volume ratio of the i-th type of patch, that is, the ratio of the number of patches included in the i-th landscape type to the number of patches included in all landscapes;

[0031] g ik represents the number of adjacent patches between the i-th type of patch and the k-th type of patch. i and k represent two different landscape types, and m represents the total number of patch types in the landscape.

[0032] In some embodiments of the present invention, the calculation method of the three-dimensional largest patch index includes:

[0033]

[0034] Wherein: V max is the largest patch volume in a certain patch type, V windowsIt is a cube formed by the projected area of the patch.

[0035] In some embodiments of the present invention, the calculation method of the island diversity index includes:

[0036] The island landscape diversity index SIDI includes: Shannon diversity index (SHDI), Shannon evenness index (SHEI), and three-dimensional contagion index (TCI); the calculation methods of each index are as follows:

[0037]

[0038] Where: P i represents the volume ratio of the i-th type of patch, that is, the ratio of the number of patches included in the i-th landscape type to the number of patches included in all landscapes; g ik represents the number of adjacent patches between the i-th type of patch and the k-th type of patch, where i and k represent two different landscape types, and m represents the total number of patch types in the landscape; α, β, γ are normalization coefficients, used to represent the proportion of the indices participating in the construction in SIDI.

[0039] In some embodiments of the present invention, the calculation method of the island three-dimensional vegetation index includes:

[0040]

[0041] Where: V i is the volume corresponding to the i-th type of vegetation, G i is the annual carbon sequestration amount corresponding to the measured i-th type of vegetation per unit area, H i is the average height of the i-th type of vegetation, α i is the shape coefficient describing the vegetation, which is the ratio of the volume of a certain type of vegetation to the volume of the cube formed by its projected area, V island is the total volume above the island ground, where V i / H i *V island The part is the spatial information part, G i / α i is the biological information part.

[0042] In some embodiments of the present invention, the calculation method of the island three-dimensional building impact index includes:

[0043] SBI = λBCR + μMBSI + νPR;

[0044] Where: BCR = S surface / V, MBSI = S area / h, PR = V / V island S surface is the total surface area of the building, V is the total volume of the building, S areais the building floor area, h is the average building height, and V island is the total volume on the island ground; BCR is the building compactness ratio, which is used to represent the measure between the building surface area and the building volume; MBSI is the average building structure index, which is used to represent the ratio of the building floor area to the building height; PR is the plot ratio; where λ, μ, and ν are normalization coefficients, which are used to represent the proportion of the participating indices in SBI.

[0045] The beneficial effects of the method and system provided by the present invention are as follows:

[0046] (1) A method for constructing a three-dimensional landscape index system of an island is proposed, which improves the shape characteristics, fragmentation degree of patch types, the occupied area of each island land type, and the spatial transfer process, and also has strong practical significance.

[0047] (2) Using the three-dimensional landscape index system to explore the island, the land use types of the island, the buildings, and the undulations of vegetation terrain on the island are more clearly quantified, and research is carried out by type, making the island landscape grid clearer and enabling a comprehensive analysis of the ecological evolution process of the island landscape. Description of the Drawings

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0049] Figure 1 is the flow chart for constructing the three-dimensional index system of the island provided by the present invention;

[0050] Figure 2a is the perspective view of the point cloud data of Tianheng Island;

[0051] Figure 2b is Figure 2a the partial enlarged view in

[0052] Figure 2c is Figure 2a the partial enlarged view in

[0053] Figure 2d is Figure 2a the partial enlarged view in

[0054] Figure 3 is the land use classification map of Tianheng Island;

[0055] Figure 4 is the digital surface model map of Tianheng Island;

[0056] Figure 5a It is the true color point cloud image of the buildings on Tianheng Island;

[0057] Figure 5b It is the result map of the point cloud classification of the buildings on Tianheng Island;

[0058] Figure 6a It is the true color point cloud image of the Tianheng Statue on Tianheng Island;

[0059] Figure 6b It is the result map of the point cloud classification of the Tianheng Statue on Tianheng Island. Specific implementation manners

[0060] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0061] The present invention provides a method for constructing a three-dimensional index of island landscapes. Starting from the perspectives of island vegetation and buildings, and supplemented by basic three-dimensional landscape indicators, a three-dimensional index system is constructed. Using the data of this three-dimensional index system, the island ecological environment can be comprehensively analyzed from the aspects of nature and human activities.

[0062] Generally speaking, the implementation manner of the method for constructing the three-dimensional index of the island landscape of the present invention is as follows.

[0063] By using unmanned aerial vehicle (UAV) oblique photogrammetry, the rapid extraction of the three-dimensional information of the island surface and the construction of a high-precision digital surface model are completed. Based on the supporting software, the obtained image is directly used to measure attributes such as height, length, area, angle, slope, etc., to obtain the information of the building facade. On this basis, the construction of the three-dimensional model of the island and the accurate extraction of the three-dimensional information of the ground objects are completed, so as to carry out the construction and analysis of the three-dimensional landscape indicators.

[0064] Specifically, the method for constructing the three-dimensional index of the island landscape of the present invention is realized through the following steps.

[0065] Data collection step: Measure the three-dimensional information of the island surface to obtain the point cloud data and remote sensing image data of the island surface.

[0066] Specifically, the point cloud data uses UAV LiDAR data. Based on the denoising batch processing process of the Terrasolid software and the support vector machine (SVM), the automatic classification and extraction of the point cloud data are realized. On this basis, the Tscan module is used for manual intervention to obtain the final classification result. The remote sensing data selects the Landsat8 30m band, and the unsupervised classification method is used for the classification of ground objects. The classification result is applied to Fragstats to calculate the two-dimensional landscape ecological index.

[0067] Point cloud data processing steps: First, perform filtering processing, generate ground points, classify the point cloud according to landscape types, and the landscape types include: buildings, low-height vegetation, medium-height vegetation, high-height vegetation, and roads; extract elevation information and create three-dimensional landscape metrics.

[0068] Remote sensing data processing steps: Radiometrically calibrate and atmospherically correct the original remote sensing data, and crop the data required for the study area; classify the remote sensing data according to landscape types, rasterize the vector data, import it into Fragstats for analysis, and calculate two-dimensional landscape metrics. The landscape types described here correspond to those in the point cloud data processing.

[0069] Two-dimensional landscape metrics include: basic landscape two-dimensional indices, and the basic landscape two-dimensional indices include one or a combination of the following indices: patch density, landscape shape index, contagion index, largest patch index, Shannon evenness index, Shannon diversity index; among them, the basic landscape two-dimensional indices are used to analyze and compare with the basic landscape three-dimensional indices to judge the rationality of the basic landscape three-dimensional indices.

[0070] Three-dimensional landscape metrics include: basic landscape three-dimensional index, island three-dimensional vegetation index, island three-dimensional building impact index, and the basic landscape three-dimensional index includes one or a combination of the following indices: three-dimensional patch density, three-dimensional landscape shape index, three-dimensional contagion index, three-dimensional largest patch index, island diversity index;

[0071] Three-dimensional index evaluation steps: Fit the basic landscape three-dimensional index with the basic landscape two-dimensional index to determine whether the trend shown by the three-dimensional index evaluation result is the same as that shown by the two-dimensional index evaluation result;

[0072] If so, determine that the evaluation of the basic landscape three-dimensional index is qualified; if not, return to the index creation stage. If so, determine that the evaluation of the basic landscape three-dimensional index is qualified; if not, return to the index creation stage, find the index with an obvious difference between the three-dimensional index calculation result and the two-dimensional index calculation result. If the volume is used to replace the area information in the original three-dimensional index creation formula, try to replace the area information in the two-dimensional formula with the surface area again to calculate the three-dimensional index; conversely, if the surface area is used to replace the area information in the original three-dimensional index creation formula, try to replace the area information in the two-dimensional formula with the volume again, recalculate and evaluate the three-dimensional index, and participate in the trend comparison again.

[0073] The above-mentioned "index with an obvious difference" can be determined by a threshold. According to the comparison between the index difference and the set threshold value, if the index difference is greater than the threshold, it is determined that there is an obvious difference.

[0074] The island ecological environment is analyzed using the three-dimensional building index of the island, the three-dimensional vegetation index of the island, and the evaluated three-dimensional index of the basic landscape.

[0075] The following introduces the calculation methods of the three-dimensional indexes of the volume of the present invention.

[0076] First, the calculation methods of the parameters used in the calculation method are introduced.

[0077] Number of patches: For a certain landscape type (one of buildings, low-height vegetation, medium-height vegetation, and high-height vegetation), based on the classified point cloud data, its quantity is determined by drawing the point cloud contour line and combining visual interpretation. Volume: Calculated based on the 2.5D volume algorithm of Cloud Compare software. Surface area: Calculated based on the 2.5D volume algorithm of Cloud Compare software. Abundance Pi: The proportion of the number of patches contained in a certain landscape type to the number of patches contained in all landscapes. The normalization coefficients α, β, γ are dynamically changing and not fixed values, changing with the sample data, and obtained using the calculation method of the normalization coefficient in mathematical theory. Height H: The height (elevation) of a certain landscape type is viewed based on the Tscan height module of Terrasolid software.

[0078] The three-dimensional patch density TPD (Three-dimensional Patch Density) is constructed based on the patch density, that is, it describes the number of patches per unit volume of a certain landscape type and is an important basic index for describing landscape fragmentation. In some embodiments of the present invention, the calculation method of the three-dimensional patch density TPD includes:

[0079]

[0080] Wherein:

[0081] N i Is the total number of patches in the i-th landscape type in the island.

[0082] V i Is the total volume of the island landscape: Calculated from the ground and the overall curved surface of the island based on the 2.5D volume algorithm of the point cloud.

[0083] The three-dimensional landscape index TLSI (Three-dimensional Landscape Shape Index) is constructed based on the landscape shape index and is a shape index describing the patches in the landscape pattern. It measures the complexity of its shape by calculating the deviation degree of the volume of a certain patch in a cube region from the volume of a unit cube. In some embodiments of the present invention, the calculation method of the three-dimensional landscape shape index includes:

[0084]

[0085] Where: E is the total length of all patch contour lines in the i-th landscape type, A surface is the total surface area of the i-th landscape, A volume is the total volume of the i-th landscape.

[0086] The three-dimensional contagion index (TCI) describes the degree of aggregation or extension advantage of different patch types in the island landscape, and is an important index for describing the landscape ecological pattern. A high contagion index value indicates that a certain type of feature patch in the landscape has formed good connectivity; on the contrary, it indicates that the landscape is a dense pattern with multiple elements. In some embodiments of the present invention, the calculation method of the three-dimensional contagion index includes:

[0087]

[0088] Where:

[0089] P i is the abundance, g ik represents the number of adjacent patches of the i-th type and the k-th type. i and k represent two different landscape types, and m represents the total number of patch types in the landscape.

[0090] The three-dimensional largest patch index (TLPI) is constructed based on the two-dimensional largest patch index, which helps to determine the dominant type of the landscape. Its size determines the richness of the landscape or the proportion of features, and reflects the direction and intensity of human activities. It is expressed by calculating the ratio of the volume of the largest patch in a certain class to the total volume of the whole island landscape. In some embodiments of the present invention, the calculation method of the three-dimensional largest patch index includes:

[0091]

[0092] Where: V max is the volume of the largest patch in a certain patch type, V windows is the cube formed by the projected area of the patch.

[0093] In some embodiments of the present invention, the calculation method of the island diversity index includes:

[0094] The island landscape diversity index SIDI includes: three-dimensional Shannon diversity index, three-dimensional Shannon evenness index, and three-dimensional contagion index; the calculation methods of each index are as follows:

[0095]

[0096] SIDI = αSHDI + βSHEI + γTCI;

[0097] Among them: TCI represents the three-dimensional spread degree, SHDI represents the three-dimensional Shannon diversity index, SHEI represents the three-dimensional Shannon evenness index, and P i is the abundance; g ik represents the number of adjacent patches of type i and type k. i and k represent two different landscape types, and m represents the total number of patch types in the landscape; α, β, γ are normalization coefficients used to represent the proportion of the indices involved in the construction in SIDI.

[0098] The island vegetation index SVI (Island Vegetation Index). Islands are isolated in the ocean and lack corridors for material and energy exchange with the mainland, being relatively independent ecosystems. Islands gradually evolve into habitats with certain vegetation communities through stages such as the invasion of herbaceous plants and ferns, the settlement of herbaceous plants, and the settlement of shrubs and trees. Due to the small area of islands, limited biodiversity, poor ecosystem stability, and being vulnerable to natural disasters and human activities. Tianheng Island is mainly flat in shape, with lush vegetation on the island, and the degree of interference by residents is different on the east and west sides. To detect the impact of vegetation density on the island's ecological environment and combine the carbon sequestration ability of plants themselves, an island vegetation impact index is thus constructed. In some embodiments of the present invention, the calculation method of the three-dimensional island vegetation index includes:

[0099]

[0100] Among them: V l is the volume corresponding to the i-th vegetation type, G i is the annual carbon sequestration amount per unit area of the measured i-th vegetation, H i is the average height of the i-th vegetation type, α i is the shape coefficient describing the vegetation, which is the ratio of the volume of a cube formed by the volume of a certain vegetation type and its projected area, V island is the total volume above the island ground, where V i / H i *V island The part is the spatial information part, G i / α i is the biological information part.

[0101] The evaluation formula for the carbon sequestration and oxygen release functions of forest ecosystems is mainly obtained from the "Specification for the Evaluation of the Service Functions of Forest Ecosystems". In the embodiments of the present invention, for the main forest resource types on Tianheng Island, the site conditions and growth status of the sample plots were investigated in June 2021 to determine the main dominant tree species on Tianheng Island. After the indicators of the measurement unit are determined, the ArcGIS software is used to perform attribute fusion on the same ecological units, and spatial and data analysis is carried out accordingly. The larger the SVI, the higher the carbon sequestration ability of the vegetation on the island, and the greater the proportion of the vegetation landscape on the whole island. On the contrary, the smaller the SVI, the more severely the vegetation on the island is affected by human activities, and the smaller the proportion of the vegetation landscape on the whole island.

[0102] The island building impact index SBI (island building impact index) is used to analyze the impact of human building activities on the island ecosystem.

[0103] Traditional two-dimensional landscape indicators mainly conduct index analysis on the landscape from six aspects: edge density, main elongation, main shape index, adjacent index measurement, main contrast index, and connectivity. Two-dimensional landscape indicators pay more attention to the planar extension. While constructing three-dimensional indices and adding floor height data, the discreteness of buildings is improved, and the research on the patch discreteness degree is deepened.

[0104] In some embodiments of the present invention, the calculation method of the island three-dimensional building impact index includes:

[0105] SBI = λBCR + μMBSI + νPR;

[0106] Where: BCR = S surface / V, MBSI = S area / h, PR = V / V island S surface is the total surface area of the building, V is the total volume of the building, S area is the floor area of the building, h is the average height of the building, V island is the total volume above the island ground;

[0107] Where: BCR is the building compactness ratio, which is used to represent the measure between the building surface area and the building volume; MBSI is the average building structure index, which is used to represent the ratio of the building area to the building height; PR is the statistical plot ratio; in the formula, λ, μ, ν are normalization coefficients, which are used to represent the proportion of the indices participating in the construction in SBI.

[0108] Specifically in this embodiment, Tianheng Island is an inhabited island. There are three villages in the island, namely the east, middle and west villages, and the buildings are mainly low-rise and mid-rise. To explore the differences between inhabited islands and uninhabited islands, a building influence coefficient is constructed based on the proportion of buildings on the island, so as to analyze the impact of human building activities. The larger the SBI, the closer the island is affected by human activities, and the proportion of buildings in the island increases. The smaller the SBI, the less the island is affected by humans, and it is mostly natural scenery.

[0109] Experimental verification.

[0110] The study area is selected as Tianheng Island in the eastern sea area of Jimo, Qingdao. The central position is at 36°25′08" north latitude and 120°57′32" east longitude. The total area is 1.46 square kilometers, the coastline is 8 kilometers long, and it is 68 kilometers away from the Qingdao wharf. Tianheng Island is an inhabited island with a permanent population of 1,200 people. The main industries are aquaculture, fishing and tourism. There are various types of buildings on the island, such as the iconic building of the Sea God Temple. The styles of the north and south slopes of the island are very different, which is typical in the field of island research.

[0111] The construction method of the three-dimensional index provided by the present invention uses multi-source data and calculation methods to construct a research on the change of the island landscape pattern from two-dimensional to three-dimensional. It is a type of transitional landscape pattern change research method, and its main framework is established on a mature two-dimensional data system. At the traditional two-dimensional level, patch density is an important indicator of landscape fragmentation. As a land type with relatively serious discretization, forest land also has strong discreteness from a three-dimensional perspective; the landscape shape index only uses two-dimensional information at the two-dimensional level and cannot reflect all the characteristics of a certain landscape type. Therefore, the building obtained by combining volume information at the three-dimensional level has better compactness.

[0112] Using the method provided by the present invention, the relevant indicators of Tianheng Island calculated are as follows.

[0113] Table 1 Landscape three-dimensional ecological index

[0114]

[0115]

[0116] From the calculation results of the above indicators, it can be seen that: from the analysis of landscape categories, the TPD of high-height vegetation and low-height vegetation is relatively large, indicating that the vegetation mainly composed of black pine and grassland has the highest degree of fragmentation in spatial distribution; the TLSI of buildings is the lowest, indicating that there is little fluctuation in space; the lower the vegetation height, the larger the TLPI, indicating that the horizontal space it occupies is smaller and the richness is more obvious. The island diversity index SIDI is 76%, and the result reflects a relatively high richness of the island's landscape, and the distribution of each section among different landscape types is relatively uniform. The larger the value, the higher the richness. SBI is 44%, indicating that most of the buildings on the island are low and regular, and the building space accounts for a relatively low proportion of the whole island, which is in line with the actual situation of the island. The larger the SBI, the more complex the building structure and the higher the space occupancy, and at the same time, it reflects a higher degree of the impact of human activities on the island's ecological environment. SVI represents the production capacity of all plants represented by the dominant species on the island. The volume proportion of all vegetation types in the whole island is about 75%, and the SVI index is 28.6%, indicating that the vegetation productivity on the island is weak and the plant height is affected by human activities and is relatively low.

[0117] By statistically comparing the relevant data of each year, the annual changes of the three-dimensional indexes of the island can be analyzed to assist in analyzing the impact of human activities on the island.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for constructing a three-dimensional index of island landscapes, characterized in that, It includes the following steps: Data acquisition step: Measuring the three-dimensional information of the island surface to obtain the point cloud data and remote sensing image data of the island surface; Point cloud data processing step: Filtering the point cloud data within the research area, generating ground points, classifying the point cloud data according to landscape types, and the landscape types include: buildings, low-height vegetation, medium-height vegetation, high-height vegetation, and roads; Extracting elevation information and creating three-dimensional landscape indicators; Remote sensing data processing step: Processing the remote sensing image data, performing radiometric calibration and atmospheric correction on the original data, and cropping the data required for the research area; Classifying the remote sensing data according to landscape types, and calculating two-dimensional landscape indicators based on Fragstats analysis; The two-dimensional landscape indicators include: basic landscape two-dimensional indices, and the basic landscape two-dimensional indices include one or a combination of the following indices: patch density, landscape shape index, contagion index, largest patch index, Shannon diversity index, Shannon evenness index; The three-dimensional landscape indicators include: basic landscape three-dimensional indices, island three-dimensional vegetation indices, and island three-dimensional building impact indices, and the basic landscape three-dimensional indices include one or a combination of the following indices: three-dimensional patch density, three-dimensional landscape shape index, three-dimensional contagion index, three-dimensional largest patch index, island diversity index; Three-dimensional index evaluation step: Fitting the basic landscape three-dimensional index with the basic landscape two-dimensional index to determine whether the trend shown by the three-dimensional index evaluation result is the same as the trend shown by the two-dimensional index evaluation result; If so, it is determined that the evaluation of the basic landscape three-dimensional index is qualified; if not, return to the index creation stage, find the index with an obvious difference between the three-dimensional index calculation result and the two-dimensional index calculation result. If the volume is used to replace the area information in the original three-dimensional index creation formula, try to replace the area information in the two-dimensional formula with the surface area and calculate the three-dimensional index; conversely, if the surface area is used to replace the area information in the original three-dimensional index creation formula, try to replace the area information in the two-dimensional formula with the volume and re-perform the three-dimensional index calculation and evaluation; Analyzing the island ecological environment using the island three-dimensional building index, the island three-dimensional vegetation index, and the evaluated basic landscape three-dimensional index; The calculation method of the three-dimensional patch density includes: ； Wherein: TPD is the three-dimensional patch density, is the total number of patches in the i type of landscape in the island. The number of patches is counted by drawing the contour line of the point cloud, and the number of all closed contour lines is used as the i total number of patches in the type of landscape; The overall volume of the island landscape: calculated from the ground and the overall curved surface of the island based on the point cloud 2.5D volume algorithm; The calculation method of the three-dimensional contagion index includes: ； Wherein: TCI is the three-dimensional spread index, indicating i the volume ratio of class patches, obtained by comparing i the total volume of class landscapes with the total volume of island landscapes; indicates i the number of adjacent patches of type k patch and i and k represent two different landscape types m indicating the total number of patch types in the landscape; The calculation method of the three-dimensional largest patch index includes: ； Wherein: TLPI is the three-dimensional maximum patch index, is the maximum patch volume in a certain patch type, is a cube formed by the projected area of the patch; The calculation method of the island diversity index includes: The island landscape diversity index includes: three-dimensional Shannon diversity index, three-dimensional Shannon evenness index, and three-dimensional contagion index; The calculation methods of each index are as follows: ； ； ； ； Wherein: TCI represents the three-dimensional spread index, SHDI represents the three-dimensional Shannon diversity index, SHEI represents the three-dimensional Shannon evenness index, SIDI represents the island landscape diversity index, represents i the volume ratio of the patch of class i the proportion of the number of patches contained in the class landscape type to the number of patches contained in all landscapes; represents i the number of adjacent patches of type k and i and k represent two different landscape types, m represents the total number of patch types in the landscape; is a normalization coefficient, used to represent the proportion of the index participating in the construction in SIDI ; The calculation method of the three-dimensional landscape shape index includes: ； Wherein: TLSI is the three-dimensional landscape shape index, and is E is i the total length of the contour lines of all patches in the type of landscape, i is the total surface area of the type of landscape, i and is the total volume of the The calculation method of the island three-dimensional vegetation index includes: ； Wherein: SVI is the three-dimensional vegetation index of the island, is i the volume corresponding to the type of vegetation, i is the annual carbon sequestration amount per unit area of the measured type of vegetation, i is the average height of the type of vegetation, is the shape coefficient of the vegetation, which is the ratio of the volume of a certain type of vegetation to the volume of the cube formed by its projected area, is the overall volume above the ground of the island, where part is the spatial information part, The calculation method of the island three-dimensional building impact index includes: ； Wherein: SBI is the three-dimensional building influence index of the island, , , , is the total surface area of the building, V is the total volume of the building, is the floor area of the building, h is the average height of the building, is the total volume above the ground of the island; BCR is the building compactness ratio, which is used to represent the measure between the building surface area and the building volume; MBSI is the average building structure index, which is used to represent the ratio of the building floor area to the building height; PR is the floor area ratio; where is the normalization coefficient, which is used to represent the proportion of the exponents involved in the construction in SBI .

2. The three-dimensional index construction method for island landscapes according to claim 1, wherein In the remote sensing data processing step, after rasterizing the classified remote sensing data, calculate the two-dimensional landscape indicators.

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