本文選題：分辨率　切入點：平滑程度　出處：《西北大學》2017年碩士論文

【摘要】：坡度是很多地表過程的重要影響因子,也是水文學、土壤學、遙感圖像處理等學科中重要的地表形態(tài)指標之一。以往對于坡度分布的研究主要側重于坡度的統(tǒng)計分布與地形類型間的關系。然而,基于DEM數(shù)據(jù)的坡度理論模型研究中,DEM分辨率對坡度理論分布的影響至關重要。本文選取五個典型樣區(qū),試圖探討在不同地形類型區(qū),坡度理論分布與分辨率的關系,并深入探討分辨率的兩個組分——地形平滑和采樣間距對高程梯度(p、q)、高程梯度聯(lián)合方差(σg)、坡度相關統(tǒng)計特征和坡度理論分布的影響。本文所得主要結論如下:(1)基于信息含量法和采樣定理法對選取的五個典型樣區(qū)DEM適宜分辨率進行了確定,結果為:拜泉樣區(qū)適宜柵格尺寸為20m,延安、綏德和橫斷山樣區(qū)適宜柵格尺寸為10m,遂寧樣區(qū)適宜柵格尺寸為5m。(2)隨著分辨率的降低,高程梯度p、q的圖像表面逐漸變得平緩和光滑,圖像表面信息含量逐漸減少;p、q值域和標準差、高程梯度聯(lián)合方差以及坡度統(tǒng)計特征值(平均值和標準差)隨分辨率的降低均逐漸減小。分辨率的兩個組分(平滑程度和采樣間距)對以上結果均有影響,但地形平滑作用都是主要影響因素,且在地形較為復雜的地區(qū),地形平滑的作用更加明顯。(3)坡度頻率和累積頻率與分辨率的關系相似:隨分辨率的降低,頻率和累積頻率曲線逐漸向低坡度段移動,坡度值域逐漸減小,頻率峰值區(qū)也逐漸變窄。根據(jù)直方圖相似度指數(shù)(HS)的結果顯示,五個樣區(qū)的HS值均大于0.8,黃土丘陵區(qū)(延安和綏德)的HS最高,說明坡度理論分布模型在對坡度分布的模擬效果整體很好,黃土丘陵區(qū)效果更佳。相比之下,極陡山地模擬效果稍欠佳。
[Abstract]:Slope is an important factor in many surface processes, as well as hydrology, soil science, In the field of remote sensing image processing and other disciplines, one of the important indicators of surface morphology. The previous study of slope distribution mainly focused on the relationship between the statistical distribution of slope and the type of terrain. However, The influence of Dem resolution on the theoretical distribution of slope is very important in the study of slope theoretical model based on DEM data. In this paper, five typical samples are selected to study the relationship between the theoretical distribution of slope and the resolution in different terrain types. The effects of topographic smoothing and sampling spacing on the elevation gradient, the joint variance of elevation gradient (蟽 g), the statistical characteristics of slope correlation and the distribution of slope theory are discussed in depth. The main conclusions of this paper are as follows: 1. The information content method and sampling theorem method are used to determine the appropriate DEM resolution of the selected five typical samples. The results showed that the suitable grid size was 20 m in Baiquan sample area, 10 m in Yan'an, Suide and Hengduan sample areas, and 5 m 路m ~ 2 in Suining sample area.) with the decrease of resolution, the image surface of elevation gradient PQ gradually became smooth and smooth. The surface information content of the image gradually decreases the range and standard deviation. The joint variance of elevation gradient and the statistical eigenvalue (mean and standard deviation) of slope decrease with the decrease of resolution. The two components of the resolution (smoothness and sampling spacing) have influence on the above results. However, topographic smoothing is the main influencing factor, and the effect of topographic smoothing is more obvious in areas with complex terrain. The relationship between slope frequency and cumulative frequency and resolution is similar: with the decrease of resolution, The curve of frequency and cumulative frequency gradually moves to the low slope, the range of slope decreases gradually, and the peak region of frequency becomes narrower. According to the histogram similarity index (HS), the results show that, The HS values of the five sample areas are all greater than 0.8, and the HS of the loess hilly region (Yan'an and Suide) is the highest, which indicates that the slope theoretical distribution model is effective in simulating the slope distribution as a whole, and the effect in the loess hilly area is better than that in the loess hilly region. The simulation effect of very steep mountain is not good.
【學位授予單位】：西北大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P208

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