how to change the orientation of an extrapolated image?

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Sreeraj R
Sreeraj R on 26 Nov 2021
Commented: Sreeraj R on 26 Nov 2021
hi everyone
i am trying to extrapolate an image. however after extrapolation the orientation of the image changed. the output image covers a different area within India. how do i fix it?
the first one is the original image and the second one is the extrapolated image however the area its covering is different from the first image. i need the second image to be an extrapolated image covering the same area as the first image.
% clc;
% clear all ;
% load coast
% data =('D:\Sreeraj\Earthdata tropomi\New folder\S5P_OFFL_L2__NO2___01012021.nc');
% % ncdisp(data)
% lon = ncread(data,'/PRODUCT/longitude');
% lat = ncread(data,'/PRODUCT/latitude');
% RF = ncread(data,'/PRODUCT/averaging_kernel');
% RF1=permute(RF,[2 3 1]);
% RF2=nan(450,4173,34);
% % RF2=flip(RF1,3);
% %to crop the study area
% for i=1:450
% for j=1:4173
% for k=1:34
% if lat(i,j)>5 & lat(i,j)<45
% RF2(i,j,k)=RF1(i,j,k);
% else
% RF2(i,j,k)=nan;
% end
% end
% end
% end
%
% for i=1:450
% for j=1:4173
% for k=1:34
% if lon(i,j)>60 & lon(i,j)<110
% RF3(i,j,k)=RF2(i,j,k);
% else
% RF3(i,j,k)=nan;
% end
% end
% end
% end
% % RF3(isnan(RF3))=0;
% lat2=lat(2:450,2591:3543);
% lon2=lon(2:450,2591:3543);
% RF4=RF3(2:450,2591:3543,:);
% % RF4(isnan(RF4))=0;
lat3=lat2(1,:)'; %%----extrapolating data
lon3=lon2(:,1);
[X,Y]=meshgrid(lon3,lat3);
%resampling data
[X1,Y1]=meshgrid(lon3(1):0.3869:lon3(end),lat3(1):0.3869:lat3(end));
for i=1:34
v=griddata(X,Y,RF4(:,:,i)',X1,Y1);
v1(:,:,i)=v;
end
the above code is what i have used for the extrapolation. kindly help me to solve this problem
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Accepted Answer

KSSV
KSSV on 26 Nov 2021
Let (X,Y) be your original grid data coordinates.
lon0 = min(X(:)) ; lon1 = max(X(:)) ;
lat0 = min(Y(:)) ; lat1 = max(Y(:)) ;
% Make new grid of desired resolution
x = lon0:0.3869:lon1 ;
y = lat0:0.3869:lat1 ;
[Xi,Yi] = meshgrid(x,y) ;
% get boundary of original grid
idx = boundary(X(:),Y(:)) ;
% USe inpolygon to pick points lying inside the region
Xi(~idx) = NaN ;
Yi(~idx) = NaN ;
Now check is (Xi,YI) satisfying your region.

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