CL_plot_swath

Description

• Plots a 2D longitude/latitude swath.

  The swath is defined by several "trajectories", from leftmost to rightmost or vice versa. For instance:

  - For 2 trajectories: trajectory1 = left side, trajectory2 = right side.

  - For 3 trajectories: trajectory1 = left side, trajectory2 = middle, trajectory3 = right side.

  The trajectories (pos) can be given in 2 ways:

  - list: list(pos1, pos2,... ), where posk is a trajectory in cartesian coordinates (3xN).

  - hypermat(3,:,:): pos(:,:,k) is then the kth trajectory (size = 3xN).

  The swath can be plotted using the following styles:

  - style = "f" ("fill"): polygons made from positions at index k and k+1 are filled with color k.

  - style = "c" ("contour"): polygons made from positions at index k and k+1 are plotted with color k.

  - style = "s" ("segment"): segments made from positions at index k are plotted with color k.

• Notes:

  - If style == "f" or "c", the last color index is not used.

  - The function implements a simple algorithm using the longitudes only to detect if a polygon contains a pole.

  The algorithm works if the positions define the points of a "real" swath whose width on Earth is less than 180 deg, Otherwise, results are unpredictable.

  - The plotted longitudes are spherical longitudes.

  - Polygons or segments that contain %nan are ignored.

  - The function creates only one graphical entity. Properties can be changed after the call, for instance by:

  h = CL_g_select(gce(), "Polyline"); h.line_mode = "on"; h.foreground = color("black");

Parameters

pos:

Points describing the swath in cartesian coordinates. (3xNxP) or list(3xN). See above for details.

win_id:

(integer or window handle, optional) Figure Id. Id of current window if omitted.

style:

(string, optional) The style used to draw the swath: "f", "c" or "s". Default is "c". (1x1)

color_id:

(integer, optional) Vector of color indices used to draw the swath. Default: black color (1xN or 1x1)

data_bounds:

(optional) View area: [longmin, latmin; longmax, latmax] in degrees. Default is [-180, -90; 180, 90].

Authors

• CNES - DCT/SB

Examples

// Generate orbit t0 = 0; // initial time kep0 = [7200.e3; 0; 1.4; 0; 0; 0]; // orbit parameters t = t0 + (0 : 1 : 95) / 1440; // days kep = CL_ex_kepler(t0, kep0, t); // orbit propagation [pos, vel] = CL_oe_kep2car(kep); // inertial position and velocity // Generate swath points (arbitrary radius) ang = 0.3; // "center angle" (rad) p1 = CL_fr_qsw2inertial(pos, vel, [cos(ang); 0; sin(ang)]); p2 = pos; p3 = CL_fr_qsw2inertial(pos, vel, [cos(ang); 0; -sin(ang)]); // Plot (filled, continuous colors) f = scf(); f.color_map = jetcolormap(101); colorbar(t(1)*1440, t($)*1440, colminmax = [1, 101]); CL_plot_swath(list(p1, p2, p3), style = "f", color_id = 1+ round(100*t/t($)));