find_dx.m

cootes提出的ASM算法的matlab实现。在cootes用于课堂使用的源代码的基础上改写。改正了原来代码中的一些错误

function dx=find_dx(s,dsP1,Theta,dTheta,x,dX,Xc,dXc);
%function dx=find_dx(s,dsP1,Theta,dTheta,x,dX,dXc);


% find dx to make M(s(1+ds),(Theta+dTheta))[x+dx]+(Xc+dXc) == X+dX , here X = M(s,Theta)[x]+dX
%           dx   = M(1/(s(1+ds)),-(Theta+dTheta))[y] - x
%           where: y = M(s,Theta)[x]+dX-dXc 


%y=M_s_Theta*x+dX-dXc;

% y=ScaleRotateTranslate(x,s,Theta,dX(1)-dXc(1),dX(end)-dXc(end));
y=ScaleRotateTranslate(x,s,Theta,0,0)+dX-dXc;

%dx=M2*y-x;

dx=ScaleRotateTranslate(y,1/(s*(dsP1)),-(Theta+dTheta),0,0)-x;