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ocssw
V2022
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Go to the source code of this file.
Functions | |
| void | matmpy (const float xm1[3][3], const float xm2[3][3], float xm3[3][3]) |
| void | matmpy_ (const float xm1[3][3], const float xm2[3][3], float xm3[3][3]) |
| void | oceuler (float a[3], float xm[3][3]) |
| void | ocorient_ (float pos[3], float vel[3], float att[3], float rm[3][3], float coef[10]) |
Function Documentation
◆ matmpy()
c Computes matrix product of 3x3 matrices xm1 and xm2
- Parameters
-
xm1 R*4 I Input Matrix xm2 R*4 I Input Matrix xm3 R*4 O Output Matrix
Definition at line 5 of file ocorient.c.
◆ matmpy_()
Definition at line 16 of file ocorient.c.
◆ oceuler()
| void oceuler | ( | float | a[3], |
| float | xm[3][3] | ||
| ) |
c Computes coordinate transformation matrix corresponding to Euler c sequence. The order of angles in the input array is yaw, roll, c pitch; according to OSC, the order of the rotations is the reverse c of this; the roll and pitch angles are about the negative Y and Z c axes, respectively, while the yaw angle is about the positive X axis. c Reference: Wertz, Appendix E; OSC, personal communication c Modification history: c c c Modified to change order of rotations to pitch, roll, yaw (-Z, -Y, -X) c F. S. Patt, GSC, September 29, 1996. c c Removed negative signs on Y and Z rotations for OCTS; order of rotations c is yaw, pitch, roll (Z, Y, X)
- Parameters
-
a R*4 I Input Array of Euler Angles (degrees) xm R*4 O Output Transformation Matrix
Definition at line 25 of file ocorient.c.
◆ ocorient_()
| void ocorient_ | ( | float | pos[3], |
| float | vel[3], | ||
| float | att[3], | ||
| float | rm[3][3], | ||
| float | coef[10] | ||
| ) |
c This subroutine performs a simple calculation of the sensor c orientation from the orbit position vector and input values of the c attitude offset angles. The calculations assume that the angles c represent the roll, pitch and yaw offsets between the local vertical c reference frame (at the spacecraft position) and the sensor frame. c Sensor tilt angles are assumed to be included in the pitch angle. c The outputs are the matrix which represents the transformation from c the geocentric rotating to sensor frame, and the coefficients which c represent the Earth scan track in the sensor frame. c The reference ellipsoid uses an equatorial radius of 6378.137 km and c a flattening factor of 1/298.257 (WGS 1984). c Subprograms Called (attached): c CROSSP Compute cross product of two vectors c EULER Compute matrix from Euler angles c MATMPY Multiply two 3x3 matrices c c Program written by: Frederick S. Patt c General Sciences Corporation c July 22, 1992 c c Modification History: c Added improved calculation of local vertical reference frame and c modified calling argument names. c F. S. Patt, September 30, 1992 c Expanded vector normalization in-line to eliminate subroutine c call. F. S. Patt, October 19, 1992 c Eliminated redundant calculations, changed to correspond to c paper, "Exact closed-form geolocation algorithm for earth c survey sensors", International Journal of Remote Sensing, Patt c and Gregg, 1993. W. Gregg, 4/5/93. c Modified to support three-dimensional view vectors by computing c coefficients array with all 10 ellipsoid terms. c F. S. Patt, November 25, 1996
- Parameters
-
pos I Orbit Position Vector ECEF (km) vel Orbit Velocity Vector ECEF (km/sec) att Attitude Offsets (Euler angles in degrees); referenced to local vertical coordinates; order is roll, pitch, yaw (X, Y, Z) rm Sensor orientation matrix coef Scan path coefficients
c Compute correction to orbit velocity vector in Earth-centered c Earth-fixed (ECEF) frame; this involves subtracting effect of Earth c rotation rate on velocity to get correct scan plane orientation in c ECEF frame.
c Determine nadir frame reference axes c Uses method of local ellipsoid approximation good to 0.3 arcsecond c Compute Z axis as local nadir vector
Definition at line 103 of file ocorient.c.
