深度学习遥感影像分类之数据集批量准备

深度学习遥感影像分类之数据集批量准备

近年来，深度学习在遥感影像地物分类中取得了一系列显著的效果。CNN可以很好的获取影像纹理信息，捕捉像素与像素之间的空间特征，因此，一个训练好的深度学习模型在地物提取中具有很大的优势。但模型的训练却是一个很繁琐的任务，需要人工准备数据集，贴标签，训练模型等。本文将以sar影像为例实现冰水二分类的数据集批量准备工作（划线取点截取小图片保存）：

1.原始sar遥感影像

2.预处理思路：

     a.人工划线：对应在冰和水上画n条线（自己设置，注意自己需要针对类别所占比例控制线条数量和长度）

     b.保存小图片：获取直线上点坐标，以每个像素点为中心取21×21的小图片（类似mnist数据集，尺寸自己设置），保存至文件夹

     c. 创建label：以保存的小图片名称+空格+类别（0或者1）将label保存至新创建的txt文档中

3.代码实现：

     a.创建一个main函数调用drawTrainingSamples(img);CreateTrainSmallImages(img);drawValSamples(img);CreateValSmallImages(img);这四个函数，功能分别是和划训练集，创建训练集，划验证集，创建验证集

clear  ;
clc ;

img =  imread ( '150905_multilook_4_s1a-ew-grd-hv-20150905t174712-20150905t174812-007583-00a7f0-002.tiff' );
%准备训练集数据
drawTrainingSamples(img);
CreateTrainSmallImages(img);

%准备验证集数据
drawValSamples(img);
CreateValSmallImages(img);

      b.drawTrainingSamples(img)

function  [] = drawTrainingSamples(img)
n_ice=4;
n_water=4;
h_im=imshow(img);
bw_train_ice= zeros ( size (img));
bw_train_water= zeros ( size (img));
fprintf ( 'please draw four lines on the picture for preparing the training sets of Ice' );
for  i  = 1:n_ice
    h = imline;
    bw = createMask(h,h_im);
    bw_train_ice=bw_train_ice+bw;
end
figure ,imshow(bw_train_ice);

 h_im=imshow(img);
 fprintf ( 'please draw four lines on the picture for preparing the training sets of Water' );
 for  i  = 1:n_water
    h = imline;
    bw = createMask(h,h_im);
    bw_train_water=bw_train_water+bw;
 end
figure ,imshow(bw_train_water);

 save ( 'bw_train_ice.mat' , 'bw_train_ice' );
 save ( 'bw_train_water.mat' , 'bw_train_water' );

       c.CreateTrainSmallImages(img)

function  [] = CreateTrainSmallImages(img)

%创建小图片
      load  bw_train_ice;
      load  bw_train_water;
       fprintf ( 'Creating training small images...' );
        [X,Y]= find (bw_train_ice==1);
        A=[X,Y];
        A;
        [a,b]= size (A);
        mkdir ( 'train' );

            for  i =1:a
                    m=A( i ,1);
                    n=A( i ,2);
                    SmallImage=img(m-10:m+10,n-10:n+10);
                    imwrite (SmallImage,[ 'train/' , num2str ( i ), '.jpg' ]);

                    fid =  fopen ( 'train.txt' ,  'a' );
                    t=[ num2str ( i ), '.jpg' ];
                    fprintf (fid,  '%s %d \n' , t,0);
                    fclose (fid);
            end

        [X,Y]= find (bw_train_water==1);
        B=[X,Y];
        B;
        [a,b]= size (B);

            for  j =1:a
                    m=B( j ,1);
                    n=B( j ,2);
                    SmallImage=img(m-10:m+10,n-10:n+10);
                     j = i + j ;
                    imwrite (SmallImage,[ 'train/' , num2str ( j ), '.jpg' ]);

                    fid =  fopen ( 'train.txt' ,  'a' );
                    t=[ num2str ( j ), '.jpg' ];
                    fprintf (fid,  '%s %d \n' , t,1);
                    fclose (fid);

            end
end

       d.drawValSamples(img)

function  [] = drawValSamples(img)
n_ice=4;
n_water=4;
h_im=imshow(img);
bw_val_ice= zeros ( size (img));
bw_val_water= zeros ( size (img));
fprintf ( 'please draw four lines on the picture for preparing the validition sets of Ice' );
for  i  = 1:n_ice
    h = imline;
    bw = createMask(h,h_im);
    bw_val_ice=bw_val_ice+bw;
end
figure ,imshow(bw_val_ice);

 h_im=imshow(img);
 fprintf ( 'please draw four lines on the picture for preparing the validition sets of Water' );
 for  i  = 1:n_water
    h = imline;
    bw = createMask(h,h_im);
    bw_val_water=bw_val_water+bw;
 end
figure ,imshow(bw_val_water);

 save ( 'bw_val_ice.mat' , 'bw_val_ice' );
 save ( 'bw_val_water.mat' , 'bw_val_water' );

       e.CreateValSmallImages(img)

function  [] = CreateValSmallImages(img)

%创建小图片
      load  bw_val_ice;
      load  bw_val_water;

        [X,Y]= find (bw_val_ice==1);
        A=[X,Y];
        A;
        [a,b]= size (A);
        mkdir ( 'val' );
          fprintf ( 'Creating validition sets small images...' );
            for  i =1:a
                    m=A( i ,1);
                    n=A( i ,2);
                    SmallImage=img(m-10:m+10,n-10:n+10);
                    imwrite (SmallImage,[ 'val/' , num2str ( i ), '.jpg' ]);

                    fid =  fopen ( 'val.txt' ,  'a' );
                    t=[ num2str ( i ), '.jpg' ];
                    fprintf (fid,  '%s %d \n' , t,0);
                    fclose (fid);
            end

        [X,Y]= find (bw_val_water==1);
        B=[X,Y];
        B;
        [a,b]= size (B);

            for  j =1:a
                    m=B( j ,1);
                    n=B( j ,2);
                    SmallImage=img(m-10:m+10,n-10:n+10);
                    j = i + j ;
                    imwrite (SmallImage,[ 'val/' , num2str ( j ), '.jpg' ]);

                    fid =  fopen ( 'val.txt' ,  'a' );
                    t=[ num2str ( j ), '.jpg' ];
                    fprintf (fid,  '%s %d \n' , t,1);
                    fclose (fid);

            end
end