CN115731361B - Geological disaster enhanced display method based on laser LiDAR data - Google Patents

Abstract

The invention discloses a geological disaster enhancement display method based on laser LiDAR data, which comprises the following steps: loading DEM data of a research area and generating a gradient map, a positive opening map and an SVF map in RVT software; using the slope map as a base map, setting the RVT software mixing mode to Nomal, and setting the opacity to 100% to obtain a processed base map; fusing the processed base map and the positive opening map by adopting a multiple mode in a mixing module, and setting the opacity to be 70% to obtain a result map; fusing the result map and the SVF map by adopting a Screen mode in a mixing module, and setting the opacity to be 50% to obtain a final result map; and carrying out geological disaster remote sensing identification according to the final result diagram. The invention has small data storage capacity; the data processing flow is relatively simple, and the characteristic of identifying the texture disasters is enhanced in a targeted manner; breaks through the application limitation caused by the defects of the image layer.

Description

Geological disaster enhanced display method based on laser LiDAR data

Technical Field

The invention relates to the technical field of information acquisition and processing, in particular to a geological disaster enhancement display method based on laser LiDAR data.

Background

China is one of the most serious geological disasters and the most threatening countries in the world. According to the data display of the natural resource department, the number of geological disaster hidden trouble points is found to be more than 33 ten thousand in China by the year 2020. 70% of the major geological disasters occurring in the last decade are out of the range of the hidden danger, and the common characteristics of high position and high concealment are presented, so that the conventional manual investigation and the conventional means are difficult to find. With the development of remote sensing technology, the airborne LiDAR technology provides a new solution for early identification of geological disasters with high positions and high concealment. The airborne LiDAR has the advantages of penetrating vegetation, acquiring real ground elevation data information, revealing slope history damage and the like. After the point cloud data acquired by the airborne LiDAR is filtered to obtain the real earth model (DEM) data, the real earth model (DEM) data is usually visualized as gray images or color images to help identify potential geological disasters of a research area.

The current mainstream visualization method comprises a mountain shadow map and a RED RELIEF IMAGE MAP (RRIM) map, which have the defects of different degrees on the enhanced display effect of geological disasters.

Mountain shadow maps are one of the most common visualization methods, consisting ofThe principle is that the brightness of the surface generated by irradiation of the ground by the imaginary sunlight at a specific angle is continuously changed, so that the distribution, fluctuation and morphological characteristics of the landform are realized to realize a stereoscopic enhancement display.

However, a single light beam cannot reveal a linear structure parallel to the light source, if the direction of the light source is changed, a completely inverted concave-convex feeling is obtained, and small terrains may be shaded, in the geological disaster identification work, mountain shading in multiple directions is often switched to avoid identification omission, so that the identification flow and data storage become more complicated.

RED RELIEF IMAGE MAP (RRIM) is proposed by foreign scholars Chiba and the like and is formed by multiplying three landform element layers of landform gradient, positive opening and negative opening. Firstly, according to DEM, respectively calculating the positive opening, the negative opening and the gradient of the terrain in SAGA and Arcgis, then adopting a grid calculator to calculate the ridge-valley index I, superposing a gradient layer on the ridge-valley index layer, adjusting the color bands and the transparency of the two layers, and finally obtaining the RRIM diagram. The technical method has the advantages of complex processing flow and high cost; the method is used for enhancing and displaying the terrains of archaeological areas, and professional enhancing and displaying research is not carried out aiming at the identification characteristics of various geological disasters.

Disclosure of Invention

Aiming at the defects in the prior art, the geological disaster enhancement display method based on the laser LiDAR data solves the problems that mountain shadows lose disaster boundary details under different illumination conditions, the mountain shadow data storage quantity in multiple directions is large, and special enhancement processing is not carried out on identification features of geological disasters.

In order to achieve the aim of the invention, the invention adopts the following technical scheme: a geological disaster enhanced display method based on laser LiDAR data comprises the following steps:

S1, loading DEM data of a research area and generating a gradient map, a positive opening map and an SVF map in RVT software;

S2, setting a RVT software mixing mode to Nomal and setting the opacity to 100 by using the gradient map as a base map, so as to obtain a processed base map;

S3, fusing the processed base map and the positive opening map by adopting a multiplex mode in a mixing module, and setting the opacity to be 70% to obtain a result map;

S4, fusing the result map and the SVF map by adopting a Screen mode in a mixing module, and setting the opacity to be 50% to obtain a final result map;

And S5, carrying out geological disaster remote sensing identification according to the final result diagram.

The beneficial effects of the invention are as follows:

1. The problem that disaster boundary details are lost in mountain shadows in a single light source direction and the data storage amount of mountain shadows in a plurality of light source directions is large is solved.

2. The RRIM graph data processing method and device solve the problems that the RRIM graph data processing flow is complex and the characteristic information of geological disasters is not subjected to special enhancement processing in the prior art.

3. The defects of a plurality of visual factor layers are overcome, and the application limit caused by the defects of the layers is broken through.

Drawings

FIG. 1 is a flow chart of the present invention.

Detailed Description

The following description of the embodiments of the present invention is provided to facilitate understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and all the inventions which make use of the inventive concept are protected by the spirit and scope of the present invention as defined and defined in the appended claims to those skilled in the art.

As shown in fig. 1, a geological disaster enhancement display method based on laser LiDAR data includes the following steps:

S1, loading DEM data of a research area and generating a gradient map, a positive opening map and an SVF map in RVT software;

S2, setting a RVT software mixing mode to Nomal and setting the opacity to 100 by using the gradient map as a base map, so as to obtain a processed base map;

S3, fusing the processed base map and the positive opening map by adopting a multiplex mode in a mixing module, and setting the opacity to be 70% to obtain a result map;

S4, fusing the result map and the SVF map by adopting a Screen mode in a mixing module, and setting the opacity to be 50% to obtain a final result map;

And S5, carrying out geological disaster remote sensing identification according to the final result diagram.

In one embodiment of the invention, the method is applied to landslide, collapse and debris flow identification and information extraction, and better visual enhancement effect than mountain shadows, SVF and RRIM is obtained.

In the remote sensing interpretation and identification of landslide, the micro-relief features such as landslide wall, landslide sill, drumlin, local bump and the like remained on the ground surface after the deformation and damage of the landslide are very important interpretation marks. The method comprises the steps of obtaining point cloud data by using an airborne LiDAR technology, filtering vegetation, obtaining a DEM, and selecting three main flow visualization methods of a mountain shadow map, an SVF map and an RRIM map to carry out remote sensing interpretation comparison with a result map layer of the method. The mountain shadow map can primarily identify the existence of potential landslide bodies for interpretation personnel with abundant interpretation experience, but has the problems that landslide boundaries are shielded by illumination shadows, and pull cracks are not obvious; SVF images eliminate the influence of shadows and give the landslide boundary black color to achieve the enhancement effect, but the lack of large-area black pixels and plasticity influences the identification work; the RRIM graph changes the tone into red, the enhancement of the landslide wall is in dark red, the enhancement of the flat ground is in white, and the effect is good but the steps are complicated. The resulting layer of the present invention improves the performance of the pull crack and secondary slide mark in the layer in addition to complementing the plasticity of the SVF, and the results are shown in table 1:

TABLE 1

In addition to landslide, which is a major type of geological disaster, collapse is also more common and is one of the types of geological disasters that have greater impact. Wherein, the identification factor of collapse comprises a dangerous rock mass before collapse and a collapsed pile body after collapse.

And selecting three main flow visualization methods of a mountain shadow map, an SVF map and an RRIM map to carry out remote sensing interpretation comparison with a result map layer of the invention. The mountain shadow map is a common mountain shadow map with a height angle of 45 degrees and an illumination angle of 315 degrees, and shadows caused by illumination directly interfere with accurate identification of boundaries of dangerous rock mass and collapsed accumulation bodies; the image layer after SVF visualization treatment removes the influence of illumination, can roughly distinguish collapsed forms, and too many black pixels lead to too low brightness of the whole image, and further needs to enhance the contrast ratio; the RRIM graph has good enhancement effect on the exposed area of the dangerous rock body and has insufficient enhancement performance on the characteristics of the collapsed pile body; in the result layer of the invention, the blocked part of the edge details in the mountain shadow map is highlighted, and the method has higher brightness than SVF and hierarchy sense than RRIM, thus enhancing the outline details of dangerous rock mass and collapse accumulation, weakening the recognition interference of other elements of the slope on collapse, and the result is shown in Table 2:

TABLE 2

The debris flow is one of the common geological disasters in mountainous areas, and has the characteristics of large impact destructive power, rapid development, strong flow capacity and the like. When interpreting a disaster as a debris flow on a remote sensing image, the following three conditions are generally required to be satisfied: ① Good water collecting condition ②, rich ③ ditch with a smooth material source and a rich channel material source, and a stacking fan. The method is characterized in that the identification of a forming area and a stacking area is critical, the forming area is generally gourd ladle-shaped, the hillside is steep, and loose solid materials are rich; the deposition area is positioned at the outlet of the gully, the longitudinal slope is gentle, a flood fan or a flushing cone is often formed, the fan surface has no fixed groove, and the fan surface is in a overflowing state.

The remote sensing interpretation comparison is carried out by three main stream visualization methods, namely mountain shadow, SVF and RRIM. The mountain shadow map only makes the tone of the accumulation area and the peripheral tone have obvious difference, and the enhancement effect gradually weakens from the channel of the circulation area upwards to the formation area; the SVF image eliminates the influence of illumination, the morphological characteristics of the whole debris flow are primarily displayed, but the brightness of the SVF image is too low, and the contrast of the SVF image needs to be further enhanced; the RRIM graph sets the main tone to be red, the enhancement effect is similar to that of the SVF graph, but the process is more complicated; in the result layer of the invention, the identification of a plurality of collapsed stacks forming a region is not interfered by shadow, the extraction of finer boundaries is helpful for the accurate calculation of the amount of material sources, the channel of the circulation region has a clearer outline appearance, the stack region is fan-shaped, and a plurality of wavy ridges which are approximately parallel to the channel exist, so that the river in front is redirected, and the result is shown in the table 3:

TABLE 3 Table 3

The fusion layer obtained by the method provided by the invention realizes the enhancement effect on the identification characteristics of various geological disasters, integrates the enhancement effects of various visual factors such as gradient, sky view factor and positive opening on the characteristics of different geological disasters into one result layer, and can be operated by Relief Visualization Toolbox software in a one-key manner, so that the problems of data redundancy, difficulty in storage and complex steps are solved, and the detail characteristic elements required in geological disaster identification are enhanced.

The invention solves the problems that disaster boundary details are lost in mountain shadows in a single light source direction and the data storage quantity of mountain shadows in a plurality of light source directions is large; the method solves the problems that the RRIM graph data processing flow is complex and the characteristic information of the geological disaster is not subjected to special enhancement processing in the prior art; the defects of a plurality of visual factor layers are overcome, and the application limit caused by the defects of the layers is broken through.

Claims (1)

1. The geological disaster enhanced display method based on the laser LiDAR data is characterized by comprising the following steps of:

S1, loading DEM data of a research area and generating a gradient map, a positive opening map and an SVF map in RVT software;

S2, setting a RVT software mixing mode to Nomal and setting the opacity to 100 by using the gradient map as a base map, so as to obtain a processed base map;

S3, fusing the processed base map and the positive opening map by adopting a multiplex mode in a mixing module, and setting the opacity to be 70% to obtain a result map;

S4, fusing the result map and the SVF map by adopting a Screen mode in a mixing module, and setting the opacity to be 50% to obtain a final result map;

And S5, carrying out geological disaster remote sensing identification according to the final result diagram.