遙感原理與應(yīng)用ppt課件(完整版)
【正文】 mage produced through optical bination of multiband images by projection through filters. ? True Colour Composite: A colour imaging process whereby the colour of the image is the same as the colour of the object imaged. ? False Colour Composite: A colour imaging process which produces an image of a colour that does not correspond to the true colour of the scene (as seen by our eyes). 48 TM1 TM2 TM3 TM4 TM5 TM6 TM7 Landsat TM 5 subscene showing the region around the Alpinforschungszentrum Rudolfsh252。 54 A linear stretch involves identifying lower and upper bounds from the histogram (usually the minimum and maximum brightness values in the image) and applying a transformation to stretch this range to fill the full range. 55 This graphic illustrates the increase in contrast in an image before (left) and after (right) a linear contrast stretch. 56 If the input range is not uniformly distributed. In this case, a histogramequalised stretch may be better. This stretch assigns more display values (range) to the frequently occurring portions of the histogram. In this way, the detail in these areas will be better enhanced relative to those areas of the original histogram where values occur less frequently 57 This graphic illustrates the rather uneven increase in contrast in an image before (left) and after (right) a histogram equalised stretch. 三、空間濾波 ? 以重點(diǎn)突出圖像上某些特征為目的。 銳化 — 突出圖像的邊緣、線性目標(biāo)或某些亮度變化率大的部分。或（近紅外 紅） /（近紅外 +紅） .對(duì)于區(qū)分和增強(qiáng)光譜亮度值雖不明顯，而不同波段的比值差異較大的地物有明顯效果?？蓪?shí)現(xiàn)數(shù)據(jù)壓縮和圖像增強(qiáng)。 二、遙感與非遙感信息的復(fù)合 主要步驟： 地理數(shù)據(jù)的網(wǎng)格化 （ 1）網(wǎng)格數(shù)據(jù)生成 （ 2）與遙感數(shù)據(jù)配準(zhǔn) 最優(yōu)遙感數(shù)據(jù)的選取 配準(zhǔn)復(fù)合 （ 1）柵格數(shù)據(jù)與柵格數(shù)據(jù) （ 2）柵格數(shù)據(jù)與矢量數(shù)據(jù)。 ? 多源信息復(fù)合的意義 :發(fā)揮不同遙感數(shù)據(jù)源的優(yōu)勢(shì) ,彌補(bǔ)某種遙感數(shù)據(jù)的不足 ,提高遙感數(shù)據(jù)的應(yīng)用性 。 2. 差值運(yùn)算： 兩幅同樣行、列數(shù)的圖像，對(duì)應(yīng)像元的亮度值相減就是差值運(yùn)算。 ② 索伯爾梯度 ③ 拉普拉斯算法 ④ 定向檢測(cè) Low and HighPass Filtering ? When we look at spatial structure, we can usually see a characteristic length scale (. size of fields, width and length of roads, etc) ? Images usually have features on lots of different length scales ? Sometimes, instead of talking about “l(fā)ength scale”, we talk instead about “spatial frequency”. ? High frequencies correspond to short distance scales。 ? 概念 :根據(jù)需要，舍棄不需要的頻率曲線，選擇適宜和需要的頻率波形曲線，重新構(gòu)成新的圖像，使一些地物或現(xiàn)象得到突出顯示
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