How to retrieve multiband data using shape file?

I have kept the data and shape file on following link

https://drive.google.com/drive/folders/1bnXx0V4V_yfUyWDfKFSxJWlNcWbApuxY?usp=sharing

I am using the code for extracting seven band data as follows;

% Get image info:

DataFile='C:\working_bpt\bands\Bagpat_7Bands.dat'

[Z,R] = readgeoraster(DataFile);

disp(size(Z));

p = R.ProjectedCRS;

[x,y] = worldGrid(R);

[lon,lat] = projinv(p,x,y);

ShapeFile='C:\working_bpt\bands\BAGHPAT.shp'

S = shaperead(ShapeFile);

info = shapeinfo(ShapeFile);

crs = info.CoordinateReferenceSystem;

[S(1).lon,S(1).lat] = projinv(crs,S(1).X,S(1).Y);

% Remove trailing nan from shapefile

rx = S(1).lon(1:end-1);

ry = S(1).lat(1:end-1);

logical_mask = inpolygon(S(1).lon,S(1).lat,rx,ry);

% Use the logical mask to extract data

extracted_data = Z(logical_mask);

disp(extracted_data);

it is giving following informations

DataFile =

'C:\working_bpt\bands\Bagpat_7Bands.dat'

5490 5490 7

ShapeFile =

'C:\working_bpt\bands\BAGHPAT.shp'

disp(size(extracted_data));

1 9

OR

ShapeFile =

'C:\working_bpt\bands\BAGHPAT.shp'

disp(extracted_data);

1794 1842 1829 1858 1934 1968 2315 2635 2578

My target is to retrieve the data from seven band data of dimensions

number of lines = 5490

number of samples = 5490

number of bands =7

and dimensions of output file are supposed to be

number of lines =1153

number of samples = 1315

number of bands =7

I request you to kindly look on it and suggest me how to get seven band data using shape file.

Answer 1

[Samay Sagar]

To extract data from the seven-band image using the shapefile, you can follow these steps. This will involve reading the image data, using the shapefile to create a mask, and applying this mask to extract the relevant data from the image. Here is how you can do it:

% Load the synthetic image data
load('sample_image.mat', 'Z', 'R');

% Read the shapefile
ShapeFile = 'sample_shapefile.shp';
S = shaperead(ShapeFile);

% Use shapefile coordinates directly
x = [S.X];
y = [S.Y];

% Remove trailing NaN from shapefile
x = x(~isnan(x));
y = y(~isnan(y));

% Convert shapefile coordinates to pixel indices
row = floor((y - R.YWorldLimits(1)) / R.CellExtentInWorldY) + 1;
col = floor((x - R.XWorldLimits(1)) / R.CellExtentInWorldX) + 1;

% Create a mask from the polygon
logical_mask = poly2mask(col, row, size(Z, 1), size(Z, 2));

% Initialize extracted data array
extracted_data = zeros([sum(logical_mask(:)), size(Z, 3)]);

% Extract data from each band
for band = 1:size(Z, 3)
    band_data = Z(:,:,band);
    extracted_data(:, band) = band_data(logical_mask);
end

disp(size(extracted_data));
disp(extracted_data);

For more information about “poly2mask” , you can refer the following documentation:

https://www.mathworks.com/help/images/ref/poly2mask.html