| Color steel plate buildings are mainly composed of metal materials and organic coating on the surface.In the process of outdoor service,the compound effect of external environmental factors will cause the aging and gradual decomposition of the coating,which affects the normal use also brings the hidden danger of building safety.Therefore,it is important to investigate the aging characteristics of color steel plate coating and the spatial and temporal aging law of color steel plate buildings,which is important for improving urban public safety and the efficiency of unauthorized building monitoring,and also provides relevant theoretical reference and spatial and temporal data for high-quality urban development and urban governance.The paper takes the color steel plate building group in the main urban area of Lanzhou as the research object,selects vector data of color steel plate buildings acquired with high-resolution images from 2013-2021,GF-2 multispectral image data and color steel plate coating test aging data,analyzes the equivalent acceleration relationship between accelerated aging of color steel plate coating and natural exposure,researches the color steel plate time series labeling method based on the measured color difference and high-resolution image,and derives the spatial and temporal distribution characteristics and aging classification results of urban color steel plate building groups are presented.The main research contents of the paper include:(1)The relationship between accelerated aging of color steel plate coating and natural exposure is analyzedThrough accelerated aging test of colored steel plate building and exposure test under natural conditions,the equivalent accelerated aging relationship of colored steel plate is obtained.The results show that:(1)The change trend of light loss rate of similar coatings under natural exposure test and accelerated aging test is basically consistent.Accelerated aging test can reproduce the characteristics of light loss rate of natural exposure.(2)The equivalent acceleration relationship of different color coatings is different.The equivalent acceleration relationship of red sample coating is 0.80 quarter/period,that of white sample coating is 1.03 quarter/period,and that of blue sample coating is 0.93 quarter/period.(2)The aging time sequence marking method of color steel plate building is studied systematicallyIn order to accurately identify the aging time of color plate buildings in GF-2 images,this paper proposes a color plate timing labeling method based on the measured color difference and high-resolution images.Firstly,the RGB information of color plate building in GF-2 is converted to CIELab color space,and then the color difference between color plate building and initial color plate is calculated based on CIEDE2000 color difference formula to get color difference data of color plate building based on GF-2 image.Secondly,the color difference data is matched with the measured color difference,and the aging time of color steel plate is back-calculated according to the equivalent acceleration relationship based on the color difference,and then the temporal sequence of color steel plate building is labeled,and the Google Earth image is used to verify and evaluate the accuracy,and the results prove that the method has high labeling accuracy.(3)The temporal and spatial distribution characteristics of colored steel plate buildings in Lanzhou City based on coating aging are studiedThe paper analyzed the vector data of color steel plate buildings in Lanzhou City from2013 to 2021,and combined with the color steel plate aging time sequence labeling method and various spatial and temporal evolution analysis methods to derive the spatial and temporal evolution characteristics and aging classification results of the color steel plate building group in Lanzhou City.It was found that:(1)In the past 9 years,the color steel plate buildings in Lanzhou are mainly concentrated in the central part of Chengguan District,most of Anning District,the northern part of Qilihe District and the eastern part of Xigu District,and the overall trend of color steel plate is increasing first and then decreasing,among which large color steel plate is increasing continuously,and small color steel plate is increasing first and then decreasing at a faster rate.(2)Among the four administrative districts,the color steel plate buildings in Chengguan District and Xigu District show an overall trend of growth,the number of color steel plate buildings in Qilihe District is the largest,and the number of color steel plate buildings in Anning District is the least,and the color steel plate buildings in Qilihe District and Anning District increase first and then decrease.(3)By aging classification,it is found that the number of new color steel plate is the most in 2013-2015,and the number of new color steel plate is the least in 2019-2021. |
