IDL 计算TVDI

it2022-05-06  0

介绍请看:http://blog.sina.com.cn/s/blog_764b1e9d0100wdrr.html

源码:

IDL 源码PRO TVDI,NDVI,LST,NBINS,RES RES = -1 SZ1 = SIZE(NDVI,/DIMENSIONS) SZ2 = SIZE(LST,/DIMENSIONS) IF N_ELEMENTS(SZ1) NE 2 OR N_ELEMENTS(SZ2) NE 2 THEN RETURN IF TOTAL(ABS(SZ1 - SZ2)) NE 0 THEN RETURN IF ~ISA(NDVI,/NUMBER) AND ~ISA(LST,/NUMBER) THEN RETURN ;FIND DYR WET PTS RANGE = [0.0,1.0] NPT_FILTER = 200 PTS = 50 DRY_PTS = [0] WET_PTS = [0] IDX = FLOOR(NDVI * NBINS) FOR I = 0, NBINS DO BEGIN PT = WHERE(IDX EQ I,CNT) IF(CNT GT NPT_FILTER) THEN BEGIN II = SORT(LST[PT]) DRY_PTS = [ DRY_PTS,PT[II[INDGEN(PTS)]] ] WET_PTS = [ WET_PTS,PT[II[-INDGEN(PTS)]] ] ENDIF END IF N_ELEMENTS(DRY_PTS) LE 1 THEN RETURN DRY_PTS = DRY_PTS[1:*] WET_PTS = WET_PTS[1:*] WET = LINFIT(NDVI[WET_PTS],LST[WET_PTS]) DRY = LINFIT(NDVI[DRY_PTS],LST[DRY_PTS]) GOOD = WHERE(NDVI GE RANGE[0] AND NDVI LE RANGE[1],CNT) IF CNT LE 0 THEN RETURN RES = MAKE_ARRAY(SIZE = SIZE(NDVI)) RES[GOOD] = (LST - POLY(NDVI[GOOD],WET)) / (POLY(NDVI[GOOD],DRY) - POLY(NDVI[GOOD],WET) ) END

说明:

主要是如何求得散点图上下两条边,我的策略是竖着切开散点,分作n个柱子。每个柱子如果总点数大于200,就统计最大最小的50个点作为干湿边的组成部分。

sort排序函数,where查找满足条件的元素的下标和个数,linefit线性拟合,poly根据拟合结果和x求得y。具体的多看帮助,那里说的详细,还有例子。

转载于:https://www.cnblogs.com/wishmo/p/3445831.html

相关资源:IDL批量计算NDVI

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