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%%% INPUT THE IMAGE FILE NAME:
dir;
fprintf(1,'\n');
disp('Computation of the extrinsic parameters from an image of a pattern');
disp('The intrinsic camera parameters are assumed to be known (previously computed)');
fprintf(1,'\n');
image_name = input('Image name (full name without extension): ','s');
format_image2 = '0';
while format_image2 == '0',
format_image2 = input('Image format: ([]=''r''=''ras'', ''b''=''bmp'', ''t''=''tif'', ''p''=''pgm'', ''j''=''jpg'') ','s');
if isempty(format_image2),
format_image2 = 'ras';
end;
if lower(format_image2(1)) == 'b',
format_image2 = 'bmp';
else
if lower(format_image2(1)) == 't',
format_image2 = 'tif';
else
if lower(format_image2(1)) == 'p',
format_image2 = 'pgm';
else
if lower(format_image2(1)) == 'j',
format_image2 = 'jpg';
else
if lower(format_image2(1)) == 'r',
format_image2 = 'ras';
else
disp('Invalid image format');
format_image2 = '0'; % Ask for format once again
end;
end;
end;
end;
end;
end;
ima_name = [image_name '.' format_image];
%%% READ IN IMAGE:
if format_image(1) == 'p',
I = double(pgmread(ima_name));
else
if format_image(1) == 'r',
I = readras(ima_name);
else
I = double(imread(ima_name));
end;
end;
if size(I,3)>1,
I = I(:,:,2);
end;
%%% EXTRACT GRID CORNERS:
fprintf(1,'\nExtraction of the grid corners on the image\n');
disp('Window size for corner finder (wintx and winty):');
wintx = input('wintx ([] = 5) = ');
if isempty(wintx), wintx = 5; end;
wintx = round(wintx);
winty = input('winty ([] = 5) = ');
if isempty(winty), winty = 5; end;
winty = round(winty);
fprintf(1,'Window size = %dx%d\n',2*wintx+1,2*winty+1);
[x_ext,X_ext,n_sq_x,n_sq_y,ind_orig,ind_x,ind_y] = extract_grid(I,wintx,winty,fc,cc,kc);
%%% Computation of the Extrinsic Parameters attached to the grid:
[omc_ext,Tc_ext,Rc_ext,H_ext] = compute_extrinsic(x_ext,X_ext,fc,cc,kc);
%%% Reproject the points on the image:
[x_reproj] = project_points(X_ext,omc_ext,Tc_ext,fc,cc,kc);
err_reproj = x_ext - x_reproj;
err_std2 = std(err_reproj')';
Basis = [X_ext(:,[ind_orig ind_x ind_orig ind_y ind_orig ])];
VX = Basis(:,2) - Basis(:,1);
VY = Basis(:,4) - Basis(:,1);
nX = norm(VX);
nY = norm(VY);
VZ = min(nX,nY) * cross(VX/nX,VY/nY);
Basis = [Basis VZ];
[x_basis] = project_points(Basis,omc_ext,Tc_ext,fc,cc,kc);
dxpos = (x_basis(:,2) + x_basis(:,1))/2;
dypos = (x_basis(:,4) + x_basis(:,3))/2;
dzpos = (x_basis(:,6) + x_basis(:,5))/2;
figure(2);
image(I);
colormap(gray(256));
hold on;
plot(x_ext(1,:)+1,x_ext(2,:)+1,'r+');
plot(x_reproj(1,:)+1,x_reproj(2,:)+1,'yo');
h = text(x_ext(1,ind_orig)-25,x_ext(2,ind_orig)-25,'O');
set(h,'Color','g','FontSize',14);
h2 = text(dxpos(1)+1,dxpos(2)-30,'X');
set(h2,'Color','g','FontSize',14);
h3 = text(dypos(1)-30,dypos(2)+1,'Y');
set(h3,'Color','g','FontSize',14);
h4 = text(dzpos(1)-10,dzpos(2)-20,'Z');
set(h4,'Color','g','FontSize',14);
plot(x_basis(1,:)+1,x_basis(2,:)+1,'g-','linewidth',2);
title('Image points (+) and reprojected grid points (o)');
hold off;
fprintf(1,'\n\nExtrinsic parameters:\n\n');
fprintf(1,'Translation vector: Tc_ext = [ %3.6f \t %3.6f \t %3.6f ]\n',Tc_ext);
fprintf(1,'Rotation vector: omc_ext = [ %3.6f \t %3.6f \t %3.6f ]\n',omc_ext);
fprintf(1,'Rotation matrix: Rc_ext = [ %3.6f \t %3.6f \t %3.6f\n',Rc_ext(1,:)');
fprintf(1,' %3.6f \t %3.6f \t %3.6f\n',Rc_ext(2,:)');
fprintf(1,' %3.6f \t %3.6f \t %3.6f ]\n',Rc_ext(3,:)');
fprintf(1,'Pixel error: err = [ %3.5f \t %3.5f ]\n\n',err_std2);
return;
% Stores the results:
kk = 1;
% Stores location of grid wrt camera:
eval(['omc_' num2str(kk) ' = omc_ext;']);
eval(['Tc_' num2str(kk) ' = Tc_ext;']);
% Stores the projected points:
eval(['y_' num2str(kk) ' = x_reproj;']);
eval(['X_' num2str(kk) ' = X_ext;']);
eval(['x_' num2str(kk) ' = x_ext;']);
% Organize the points in a grid:
eval(['n_sq_x_' num2str(kk) ' = n_sq_x;']);
eval(['n_sq_y_' num2str(kk) ' = n_sq_y;']);
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