cube5

correlate view image (view1.jpg) with 3D model

% set cube
cube1

% orthonormal projection
points = [0 0 0 1; 1 0 0 1; 1 1 0 1; 0 1 0 1;
    0 0 1 1; 1 0 1 1; 1 1 1 1; 0 1 1 1];
axis equal
T = view;
viewinfo
pc = ones(8,1)*[camtarget() 0];
p = points*T';

% orthonormal calculation
xp = p(:,1);
yp = p(:,2);

% projective calculation
%xp=p(:,1)./p(:,3);
%yp=p(:,2)./p(:,3);

xc = [xp(1:4); xp(1)];
yc = [yp(1:4); yp(1)];
plot(xc,yc,'b','LineWidth',2);
hold on
xc = [xp(5:8); xp(5)];
yc = [yp(5:8); yp(5)];
plot(xc,yc,'g','LineWidth',2);
for k=0:3
    plot([xp(1+k) xp(5+k)],[yp(1+k) yp(5+k)],'r','LineWidth',2);
end
plot(xp(1),yp(1),'ko','MarkerSize',8);
hold off

camera position: -4.32091 -5.24533 4.83013
camera target: 0.5 0.5 0.5
camera up vector: 0 0 1
projection: orthographic
az -40 el 30
view matrix
    0.7660   -0.6428         0         0
    0.3214    0.3830    0.8660         0
   -0.5567   -0.6634    0.5000         0
         0         0         0    1.0000

load view1
idx = [4 1 2 5 6 7 8];
xv = pts(:,1);
yv = pts(:,2);
xfit = polyfit(xp(idx),xv,1);
yfit = polyfit(yp(idx),yv,1);
fprintf('xfit %g %g\n',xfit);
fprintf('yfit %g %g\n',yfit);
xim = polyval(xfit,xp(idx));
yim = polyval(yfit,yp(idx));
figure(2)
%plot(xim-xv,yim-yv,'kx');
show_points(xim-xv,yim-yv);
axis square
s  = 2;
ticks = linspace(-1,1,11)*s;
axis([-s s -s s])
set(gca,'YTick',ticks)
set(gca,'XTick',ticks)
grid
xlabel('x-error (pixels)');
ylabel('y-error (pixels)');

xfit 342.513 293.301
yfit -342.071 287.52

Published with MATLAB® 7.9