palDcmpf
Decompose an [x,y] linear fit into its constituent parameters: zero points, scales,
nonperpendicularity and orientation
Description:
The model relates two sets of [x,y] coordinates
as follows. Naming the elements of coeffs:
coeffs[0] = A
coeffs[1] = B
coeffs[2] = C
coeffs[3] = D
coeffs[4] = E
coeffs[5] = F
the model transforms coordinates [x1,y1] into coordinates [x2,y2] as follows:
x2 = A +
B ∗ x1
+ C
∗ y1
y2 = D +
E ∗ x1
+ F
∗ y1
The transformation can be decomposed into four steps:
1) Zero points:
x’
= xz +
x1
y’
= yz +
y1
2) Scales:
x’
’
= xs ∗
x’
y’
’
= ys ∗
y’
3) Nonperpendicularity:
x’
’
’
= cos(perp / 2) ∗
x’
’
+ sin(perp
/ 2) ∗ y’
’
y’
’
’
= sin(perp / 2) ∗
x’
’
+ cos(perp
/ 2) ∗ y’
’
4) Orientation:
x2 = cos(orient) ∗
x’
’
’
+
sin(orient) ∗
y’
’
’
y2 = -sin(orient) ∗
y’
’
’
+
cos(orient) ∗
y’
’
’
Invocation
palDcmpf ( double coeffs[6], double
∗xz, double
∗yz, double
∗xs, double
∗ys, double
∗perp, double
∗orient
)
Arguments
coeffs = double[6] (Given)
transformation coefficients (see note)
xz = double
(Returned)
x zero point
yz = double (Returned)
y zero point
xs = double (Returned)
x scale
ys
= double (Returned)
y scale
perp = double (Returned)
nonperpendicularity (radians)
orient =
double (Returned)
orientation (radians)
See also
palFitxy, palPxy, palInvf and palXy2xy
Copyright © 2012 Science and Technology Facilities Council.
Copyright © 2014 Cornell University.
Copyright © 2015 Tim Jenness