def sfs2shtools(self, lighting):
'''
convert sfs SH to shtools
--we use shtools to rotate the coordinate:
we use shtools to rotate the object:
we need to use x convention,
we use shtools to rotate the coordinate:
we need to use x convention,
alpha_x = pi/2 (clock-wise rotate along z axis by pi/2)
beta_x = -pi/2 (contour clock-wise rotate along new x by pi/2)
gamma_x = 0
then y convention is:
alpha_y = alpha_x - pi/2 = 0
beta_y = beta_x = -pi/2
gamma_y = gamma_x + pi/2 = pi/2
reference: https://shtools.oca.eu/shtools/pyshrotaterealcoef.html
'''
new_lighting = np.zeros(lighting.shape)
n = lighting.shape[0]
for i in range(n):
shMatrix = shtools_sh2matrix(lighting[i,:], self.SH_DEGREE)
# rotate coordinate
shMatrix = SHRotateRealCoef(shMatrix, np.array([0, -np.pi/2, np.pi/2]), self.dj)
# rotate object
#shMatrix = SHRotateRealCoef(shMatrix, np.array([np.pi/2, -np.pi/2, 0]), self.dj)
new_lighting[i,:] = shtools_matrix2vec(shMatrix)
return new_lighting
def process_SH(sh):
'''
preprocess the lighting:
normalize the lighting so the DC component will be within
range 0.7 to 0.9
'''
# if sh is a 3x9 vector, conver it to gray
if sh.shape[0] == 3:
# RGB2Gray
coeffs_matrix_R = shtools_sh2matrix(sh[0,:], SH_DEGREE)
tmp_envMap_R = MakeGridDH(coeffs_matrix_R, lmax=255, lmax_calc=SH_DEGREE, sampling=2, norm=4)
coeffs_matrix_G = shtools_sh2matrix(sh[1,:], SH_DEGREE)
tmp_envMap_G = MakeGridDH(coeffs_matrix_G, lmax=255, lmax_calc=SH_DEGREE, sampling=2, norm=4)
coeffs_matrix_B = shtools_sh2matrix(sh[2,:], SH_DEGREE)
tmp_envMap_B = MakeGridDH(coeffs_matrix_B, lmax=255, lmax_calc=SH_DEGREE, sampling=2, norm=4)
tmp_envMap = 0.299*tmp_envMap_R + 0.587*tmp_envMap_G + 0.114*tmp_envMap_B # from opencv document
tmp_SH = pyshtools.expand.SHExpandDH(tmp_envMap, sampling=2, lmax_calc=2, norm=4)
sh = shtools_matrix2vec(tmp_SH)
coeffs_matrix = shtools_sh2matrix(sh, SH_DEGREE)
# random rotate
dj = djpi2(SH_DEGREE)
sh_angle = np.random.rand()*2*np.pi
coeffs_matrix = SHRotateRealCoef(coeffs_matrix, np.array([sh_angle, 0, 0]), dj)
factor = (np.random.rand()*0.2 + 0.7)/sh[0]
tmp_envMap = MakeGridDH(coeffs_matrix, lmax=255, lmax_calc=SH_DEGREE, sampling=2, norm=4)
tmp_envMap = tmp_envMap/factor
tmp_SH = pyshtools.expand.SHExpandDH(tmp_envMap, sampling=2, lmax_calc=2, norm=4)
sh = shtools_matrix2vec(tmp_SH)
sh = sh[...,None]
if sh[0] < 0.5 or sh[0] > 1.0:
# normalize it again if it is too dark or bright
factor = (np.random.rand()*0.2 + 0.7)/sh[0]
coeffs_matrix = shtools_sh2matrix(sh, SH_DEGREE)
tmp_envMap = MakeGridDH(coeffs_matrix, lmax=255, lmax_calc=SH_DEGREE, sampling=2, norm=4)
tmp_envMap = tmp_envMap*factor
tmp_SH = pyshtools.expand.SHExpandDH(tmp_envMap, sampling=2, lmax_calc=2, norm=4)
sh = shtools_matrix2vec(tmp_SH)
sh = sh[...,None]
return sh, factor, sh_angle