If a
WCS exists, then nWcsProj is returned
as nWcsProj in the table below.CImage:GetWcsProj
The GetWcsProj method returns an integer code for the world coordinate system ("WCS") projection used by the image.
nWcsProj = CImage:GetWcsProj()
If a
WCS exists, then nWcsProj is returned
as nWcsProj in the table below.
If
no WCS exists, then -1 is returned.
The mathematical relationship between pixel location and world coordinates is known as the world coordinate projection. The projection type is represented in the FITS header using the CTYPEn keyword, where n refers to the axis dimension. Equatorial calibration usually employs the "Tangent Plane (gnomonic)" projection with CTYPEn Code = TAN. In the FITS header, this equatorial projection for right ascension (axis 1) and declination (axis 2) appears as CTYPE1 = 'RA---TAN' and CTYPE2 = 'DEC--TAN'.
Mira supports the types of WCS projection listed in the table below. The projection type nWcsProj is returned by the present method. The CTYPEn Code is listed in FITS header as the string value of the CTYPEn keyword. The Description is reported by the List WCS Keywords menu command of the Mira user interface.
|
nWcsProj |
CTYPEn Code |
Description |
|
-1 |
|
Pixel WCS (default, no WCS) |
|
0 |
LIN |
Linear projection |
|
1 |
AZP |
Zenithal / Azimuthal Perspective |
|
2 |
TAN |
Tangent Plane (gnomonic) |
|
3 |
SIN |
Orthographic / synthesis |
|
4 |
STG |
Stereographic |
|
5 |
ARC |
Zenithal / azimuthal equidistant |
|
6 |
ZPN |
Zenithal / azimuthal Polymomial |
|
7 |
ZEA |
Zenithal / azimuthal Equal Area |
|
8 |
AIR |
Airy |
|
9 |
CYP |
Cylindrical Perspective |
|
10 |
CAR |
Cartesian |
|
11 |
MER |
Mercator |
|
12 |
CEA |
Cylindrical Equal Area |
|
13 |
COP |
Conic Perspective(COP) |
|
14 |
COD |
Conic equidistant |
|
15 |
COE |
Conic Equal Area |
|
16 |
COO |
Conic Orthomorphic |
|
17 |
BON |
Bonne |
|
18 |
PCO |
Polyconic |
|
19 |
GLS |
Sanson - Flamsteed(Global Sinusoidal) |
|
20 |
PAR |
Parabolic |
|
21 |
AIT |
Hammer - Aitoff |
|
22 |
MOL |
Mollweide |
|
23 |
CSC |
COBE quadrilateralized Spherical Cube |
|
24 |
QSC |
Quadrilateralized Spherical Cube |
|
25 |
TSC |
Tangential Spherical Cube |
|
26 |
NCP |
Special case of Orthographic / synthesis |
|
27 |
DSS |
Digitized Sky Survey plate solution |
|
28 |
PLT |
Plate fit polynomials(SAO) |
|
29 |
TNX |
Tangent Plane (gnomonic, NOAO with corrections) |
Subpixel Coordinate Definition
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