def _grid(self, corners=False):
"""Create an xy grid of coordinates for heliographic array.
Uses meshgrid. If corners is selected, this function will shift
the array by half a pixel in both directions so that the corners
of the normal array can be accessed easily.
"""
# Retrieve integer dimensions and create arrays holding
# x and y coordinates of each pixel
xDim = np.int(np.floor(self.im_raw.dimensions[0].value))
yDim = np.int(np.floor(self.im_raw.dimensions[1].value))
if corners:
xRow = (np.arange(0, xDim + 1) - self.X0 - 0.5)*self.xScale
yRow = (np.arange(0, yDim + 1) - self.Y0 - 0.5)*self.yScale
xg, yg = M.meshgrid(xRow, yRow)
rg = M.sqrt(xg**2 + yg**2)
self.Rg = rg
else:
xRow = (np.arange(0, xDim) - self.X0)*self.xScale
yRow = (np.arange(0, yDim) - self.Y0)*self.yScale
xg, yg = M.meshgrid(xRow, yRow)
rg = M.sqrt(xg**2 + yg**2)
self.xg = xg
self.yg = yg
self.rg = rg
return xg, yg
def _hpc_hcc(self, x, y):
"""Converts hpc coordinates to hcc coordinates.
x -- x coordinate in arcseconds
y -- y coordinate in arcseconds
Calculations taken and shortened from sunpy.wcs.
"""
x *= np.deg2rad(1)/3600.0
y *= np.deg2rad(1)/3600.0
q = self.dsun * M.cos(y) * M.cos(x)
distance = q**2 - self.dsun**2 + self.RSUN_METERS**2
distance = q - M.sqrt(distance)
rx = distance * M.cos(y) * M.sin(x)
ry = distance * M.sin(y)
rz = M.sqrt(self.RSUN_METERS**2 - rx**2 - ry**2)
return rx, ry, rz
def _hcc_hg(self, x, y, z):
"""Converts hcc coordinates to Stonyhurst heliographic.
x - x coordinate in meters
y - y coordinate in meters
z - z coordinate in meters
Calculations taken and shortened
from sunpy.wcs.
"""
cosb = M.cos(M.deg2rad(self.B0))
sinb = M.sin(M.deg2rad(self.B0))
hecr = M.sqrt(x**2 + y**2 + z**2)
hgln = M.arctan2(x, z*cosb - y*sinb) \
+ M.deg2rad(self.L0)
hglt = M.arcsin((y * cosb + z * sinb)/hecr)
return hgln*180/np.pi, hglt*180/np.pi
