IDL遥感应用入门（16）：使用IDL生成动画（GIF图）

2014-01-17 · IDL遥感应用教程

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麻辣GIS » GIS笔记 » IDL遥感应用教程 » IDL遥感应用入门（16）：使用IDL生成动画（GIF图）

在之前的文章中，我介绍了一种使用IDL自带的XINTERANIMATE函数生成动画的方法，但是这种方法有一种致命的缺点，没有colorbar和经纬度，这对于一幅遥感图像来说是不完整的。

针对上面的问题，我做了如下的思考。

动画可以用GIF图片展示，参照：分享一个IDL写GIF的方法
所有对象图形法绘制的图像可以存为文件，参照：IDL保存图像（对象图形法）

基于上面的两点思考，我结合分享一个IDL写GIF的方法一文中所给的过程，重新写了教程15的代码

全部代码

;Author:Sailor
;2014-01-17

PRO Course_14

;定义文件路径
MyRootDir='D:\10\'

;遍历文件夹
filearr = file_search(MyRootDir,'*.nc',count=num)
sstdisplay=intarr(4096,2048,num)
FOR fileindex=0,num-1,1 DO BEGIN
    nid = ncdf_open(filearr[fileindex], /nowrite )

    ; inquire about this file; returns structure
    file_info = ncdf_inquire(nid)

    ; print out the dimensions of this file
    FOR dimid=0, file_info.ndims -1 DO BEGIN
    ncdf_diminq, nid, dimid, name, size
    print, ' ---> dimension ' + name  + ' is: ', size 
    ENDFOR

    FOR varid=0, file_info.nvars-1 DO BEGIN
    ; inquire about the variable; returns structure
    var = ncdf_varinq( nid, varid )
    print,var
    print,'========================'
    ;read all attributes
    FOR var_att_id=0,var.natts -1 DO BEGIN
        att_name = ncdf_attname( nid, varid, var_att_id )
        print,att_name
        ncdf_attget, nid, varid, att_name, tematt
        print,string(tematt)
    ENDFOR
    ENDFOR

    ;read sst
    sstid = ncdf_varid(nid, 'analysed_sst')
    ncdf_varget, nid, sstid, sst
    sst=sst*0.01+273.150
    print,size(sst)
    landindex=where(sst eq min(sst))
    sst[landindex]=max(sst)+1
    print,max(sst),min(sst)
    sst=shift(sst,2048)

    Img=image(sst,rgb_table=39,title=filearr(fileindex),grid_units=1,POSITION=[0.1,0.2,0.9,0.9])
    xaxis=axis(TARGET=Img,'X',LOCATION=[0,0],AXIS_RANGE=[-180,180],MINOR=0, MAJOR=19,COORD_TRANSFORM=[-180,360.0/4096.0],title='Longitude(°)')
    yaxis=axis(TARGET=Img,'Y',LOCATION=[0,0],AXIS_RANGE=[-90,90],MINOR=0, MAJOR=7,COORD_TRANSFORM=[-90,180.0/2048.0],title='Latitude(°)')
    c1 = COLORBAR(rgb_table=39,RANGE=[-2+273.15,34+273.15],ORIENTATION=0,TITLE='(K) ',POSITION=[0.1,0.1,0.9,0.15])
    Img.save,MyRootDir+strtrim(string(fileindex),2)+'a.jpg'

ENDFOR

;读取所有的图像
gifarr = file_search(MyRootDir,'*a.jpg',count=num)
in_filenamelist=gifarr
outfname=MyRootDir+'a.gif'
delay_time=20
create_gif_animation,gifarr,outfname,delay_time
spawn,outfname
END

PRO create_gif_animation,in_filenamelist, outfname, delay_time
    COMPILE_OPT IDL2

    ;Get the number of input files.
    file_nums = N_ELEMENTS(in_filenamelist)

    IF (file_nums GT 0) AND ~STRCMP(in_filenamelist[0], '') THEN BEGIN
        FOR i = 0, file_nums - 1 DO BEGIN
            img = READ_IMAGE(in_filenamelist[i], red, green, blue)

            ;Get the size information.
            img_s = SIZE(img)

            ;If the dimension of the img is 3-D, then convert it to a index image first.
            IF (img_s[0] EQ 3) THEN BEGIN
                img_idx = COLOR_QUAN(img[0, *, *], img[1, *, *], img[2, *, *], tbl_r, tbl_g, tbl_b)

                ;Reverse array in the second dimension.
                img_idx = REFORM(img_idx)

                WRITE_GIF, outfname, img_idx, tbl_r, tbl_g, tbl_b, $
                            DELAY_TIME = delay_time, /MULTIPLE, REPEAT_COUNT = 0
            ENDIF

            ;If the dimension of the img is 2-D, then write it to the gif file directly.
            IF (img_s[0] EQ 2) THEN BEGIN
                img =REFORM(img)
                IF (N_ELEMENTS(red) GT 0) AND (N_ELEMENTS(green) GT 0) AND (N_ELEMENTS(blue) GT 0) THEN BEGIN

                    WRITE_GIF, outfname, img, red, green, blue, DELAY_TIME = delay_time, /MULTIPLE, REPEAT_COUNT = 0
                ENDIF
            ENDIF
        ENDFOR

        ;Close the file.
        WRITE_GIF, outfname, /CLOSE
    ENDIF
END