Visibility parameters (angles, distance, ...) for a spherical planet
[par2]=CL_gm_visiParams(sat_radius,target_radius,type_par1,par1,type_par2) [res1,..resN]=CL_gm_visiParams(sat_radius,target_radius,type_par1,par1,[type1,..,typeN]) [result]=CL_gm_visiParams(sat_radius,target_radius,type_par1,par1,'all')
Computes various visibility parameters:
- satellite's semi view-angle (sat): angle between the descending vertical and the direction of the target location
- satellite's elevation (elev): elevation of the satellite as seen from the target location
- satellite's incidence (incid = pi/2 - elev): incidence of the target-satellite direction from the target location
- distance (dist): distance between the satellite and the target location
- centre angle (cen): angle between the (planet centre -> satellite) direction and the (planet centre -> target location) direction.
Given the distance from the planet centre to the satellite (sat_radius), the distance from the planet centre to the target (target_radius) and one of the following parameters (type_par1):
type_par1 = 'sat' , par1 = satellite's semi view angle in radians.
type_par1 = 'elev' , par1 = elevation from the target location in radians.
type_par1 = 'incid' , par1 = incidence (=pi/2-elev) from the target location in radians.
type_par1 = 'dist' , par1 = distance between the target location and the satellite in meters.
type_par1 = 'cen' , par1 = centre angle: angle from the planet centre between the target location and the satellite in radians.
The function computes par2 whose type is defined by type_par2
type_par2 can also be an array of strings (any of the 5 parameters above), or 'all' and in that case the result is a structure whose fields are the 5 parameters above
Notes:
- A spherical planet is assumed.
- If the input parameter is 'sat' there usually exist 2 possible solutions. But only the one for which the elevation is positive is computed.
Distance from the satellite to the planet centre (satellite altitude + planet radius) [m] (1xN)
Distance from the target to the planet centre (target altitude + planet radius) [m] (1xN)
(string) Type of input parameter par1. It can be 'sat', 'elev', 'incid', 'dist', 'cen'
Satellite's semi view angle, elevation, indicence, distance or centre angle [rad,m] (1xN)
(string) Type of ouput parameter(s) to be computed. It can be 'sat', 'elev', 'incid', 'dist', 'cen' or a vector contaning any of them, or 'all'. If type_par2 == 'all', a structure is returned.
Computed value(s): [rad,m] (1xN)
CNES - DCT/SB