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GIMMS NDVI3g是最新发布的GIMMS的植被覆盖数据，原始文件格式为“geo10apr15a.n18-VI3g”。
原始产品转Geottif，生成NDVI和Flag两个文件，使用的时候按照可信的Flag进行分析。
在其他人代码的基础上进行了封装，指定原始格式的文件夹，直接批量算。
Matlab代码如下：
% Created by Yuke Zhou
% Version 1.0
% 12 Feb, 2015
% Description:
% Convert Raw Data(GIMMS NDVI3g) to
% GeoTIFF and project to GeoCoodSystem 'WGS84'
% Output:
% A NDVI file with its real value
% A flag file indicating the piexl source
% Thanks to Li Xu. His blog http://bbs.sciencenet.cn/home.php?mod=space&uid=1148346&view=lixujeremy
% Thanks to Prof. Nan(giscn@msn.com) for inspiring.
% His code: http://nanzt.info/2797.html
% run as: ndvi3g2geotiff_Function('D:\gisData\GIMSS_NDVI\3g\1980s\', '*VI3g', 'D:\gisData\GIMSS_NDVI\3g\NDVI_Flag\')
function [] = ndvi3g2geotiff_Function( inFilePath, inFilePattern, outFilepath )
files = dir( [inFilePath, inFilePattern] );
num_files = length(files);
for i = 1:num_files
ndvi_FileName = files(i).name;
ndvi3g = [inFilePath, ndvi_FileName];
%%ndvi3g='geo82dec15a.n07-VI3g';
% Image info
col = 4320;
row = 2160;
% Read Raw Data
fid = fopen(ndvi3g,'r','b');
A=fread(fid,col*row, '*int16');
fclose(fid);
A=reshape(A,row,col);
A = A';
A = rot90(A,3);
A = fliplr(double(A));
% Define the Lat/Long range
%LonRange=[-180+1/24:1/12:180-1/24];
%LatRange=[-90+1/24:1/12:90-1/24];
% Write a Data Referenced to Geographic Coordinates
R=georasterref('RasterSize', [row, col], 'Latlim', [-90+1/24, 90-1/24],...
'Lonlim', [-180+1/24, 180-1/24], 'ColumnsStartFrom', 'north');
% Ouput NDVI.tif
disp('...Writing out NDVI file...');
ndvi=floor(A./10)./1000;
ndvipath=[outFilepath, ndvi_FileName, '_NDVI.tif'];
geotiffwrite(ndvipath, ndvi, R);
fprintf('%s done!\n', ndvipath);
% Output Flag.tif
disp('...Writing out Flag file...');
flag=A-floor(A./10) .* 10 +1;
flagpath=[outFilepath, ndvi_FileName, '_Flag.tif'];
geotiffwrite(flagpath, flag, R);
fprintf('%s done!\n', flagpath);
disp('END');
end
end
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