| """Different Reflectance function definition. |
| |
| Author: Travis Driver |
| """ |
| import numpy as np |
|
|
| from typing import Tuple |
|
|
|
|
| def lunar_lambert_reflectance( |
| R_CB: np.ndarray, r_BC_C: np.ndarray, l_B: np.ndarray, s_C: np.ndarray, n_B: np.ndarray |
| ) -> Tuple[float, float, float, float]: |
| s_B = (R_CB.T @ s_C.reshape((3, -1))).flatten() |
| r_B = (-R_CB.T @ r_BC_C.reshape((3, -1))).flatten() |
| e_B = r_B - l_B |
| e_B /= np.linalg.norm(e_B) |
| cs = np.sum(s_B * n_B) |
| ce = np.sum(e_B * n_B) |
| phi = np.arccos(np.sum(s_B * e_B)) |
| L = np.exp(-np.rad2deg(phi) / 60.0) |
| reflect = (1 - L) * cs + L * 2.0 * cs / (cs + ce) |
|
|
| return reflect, np.arccos(cs), np.arccos(ce), phi |
|
|
|
|
| def schroder2013_reflectance( |
| R_CB: np.ndarray, r_BC_C: np.ndarray, l_B: np.ndarray, s_C: np.ndarray, n_B: np.ndarray |
| ) -> Tuple[float, float, float, float]: |
| s_B = (R_CB.T @ s_C.reshape((3, -1))).flatten() |
| r_B = (-R_CB.T @ r_BC_C.reshape((3, -1))).flatten() |
| e_B = r_B - l_B |
| e_B /= np.linalg.norm(e_B) |
| cs = np.sum(s_B * n_B) |
| ce = np.sum(e_B * n_B) |
| phi = np.arccos(np.sum(s_B * e_B)) |
|
|
| cp0, cp1 = 0.830, -7.22e-3 * 180 / np.pi |
| L = cp0 + cp1 * phi |
|
|
| c0, c1, c2, c3, c4 = ( |
| 0.301, |
| -5.17e-3 * 180.0 / np.pi, |
| 5.51e-5 * (180.0 / np.pi) ** 2, |
| -3.13e-7 * (180.0 / np.pi) ** 3, |
| 0.699e-9 * (180.0 / np.pi) ** 4, |
| ) |
| aeq = c0 + c1 * phi + c2 * phi ** 2 + c3 * phi ** 3 + c4 * phi ** 4 |
|
|
| reflect = aeq / 0.301 * ((1 - L) * cs + L * 2.0 * cs / (cs + ce)) |
|
|
| return reflect, np.arccos(cs), np.arccos(ce), phi |
|
|
