pro sam_pix_to_ab,r0,theta,alpha=alpha,beta=beta
alpha=dblarr(320,240)
beta=dblarr(320,240)
if n_elements(r0) eq 0 then r0=[164.5,120.6,-21200]
if n_elements(theta) eq 0 then theta=!dtor*15.5d
n=[sin(theta),0,cos(theta)]
nx=n[0]
ny=n[1]
nz=n[2]
mx=0
my=1
mz=-my*ny/nz
m=[mx,my,mz]
m/=norm(m)
p=crossp(m,n)
A_r2i=[[P],[M],[N]]
A_i2r=transpose(A_r2i)
for i=0,319 do begin
for j=0,239 do begin
r_i=[i,j,0]
r_r=A_i2r ## r_i
rt=r_r-r0
alpha[i,j]=-atan(rt[0]/rt[2])
beta[i,j]=atan(rt[1]/rt[2])
end
end
alpha=alpha*60d*180d/!dpi
beta=beta*60d*180d/!dpi
end