GravMag:Calculating the derivatives of the gravity anomaly using FFT

Calculating the derivatives of the gravity anomaly using FFT

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Out:

D:\MyWeb\geoistdoc\examples\tutorials\pfm_transform_deriv.py:76: UserWarning: Matplotlib is currently using agg, which is a non-GUI backend, so cannot show the figure.
  plt.show()
D:\MyWeb\geoistdoc\examples\tutorials\pfm_transform_deriv.py:76: UserWarning: Matplotlib is currently using agg, which is a non-GUI backend, so cannot show the figure.
  plt.show()

import matplotlib.pyplot as plt
from geoist import gridder
from geoist.inversion import geometry
from geoist.pfm import prism, pftrans, giutils
from geoist.vis import giplt

model = [geometry.Prism(-1000, 1000, -1000, 1000, 0, 2000, {'density': 100})]
area = (-5000, 5000, -5000, 5000)
shape = (51, 51)
z0 = -500
xp, yp, zp = gridder.regular(area, shape, z=z0)
gz = giutils.contaminate(prism.gz(xp, yp, zp, model), 0.001)

# Need to convert gz to SI units so that the result can be converted to Eotvos
gxz = giutils.si2eotvos(pftrans.derivx(xp, yp, giutils.mgal2si(gz), shape))
gyz = giutils.si2eotvos(pftrans.derivy(xp, yp, giutils.mgal2si(gz), shape))
gzz = giutils.si2eotvos(pftrans.derivz(xp, yp, giutils.mgal2si(gz), shape))

gxz_true = prism.gxz(xp, yp, zp, model)
gyz_true = prism.gyz(xp, yp, zp, model)
gzz_true = prism.gzz(xp, yp, zp, model)

plt.figure()
plt.title("Original gravity anomaly")
plt.axis('scaled')
giplt.contourf(xp, yp, gz, shape, 15)
plt.colorbar(shrink=0.7)
giplt.m2km()

plt.figure(figsize=(14, 10))
plt.subplots_adjust(top=0.95, left=0.05, right=0.95)
plt.subplot(2, 3, 1)
plt.title("x deriv (contour) + true (color map)")
plt.axis('scaled')
levels = giplt.contourf(yp, xp, gxz_true, shape, 12)
plt.colorbar(shrink=0.7)
giplt.contour(yp, xp, gxz, shape, 12, color='k')
giplt.m2km()
plt.subplot(2, 3, 2)
plt.title("y deriv (contour) + true (color map)")
plt.axis('scaled')
levels = giplt.contourf(yp, xp, gyz_true, shape, 12)
plt.colorbar(shrink=0.7)
giplt.contour(yp, xp, gyz, shape, 12, color='k')
giplt.m2km()
plt.subplot(2, 3, 3)
plt.title("z deriv (contour) + true (color map)")
plt.axis('scaled')
levels = giplt.contourf(yp, xp, gzz_true, shape, 8)
plt.colorbar(shrink=0.7)
giplt.contour(yp, xp, gzz, shape, levels, color='k')
giplt.m2km()
plt.subplot(2, 3, 4)
plt.title("Difference x deriv")
plt.axis('scaled')
giplt.pcolor(yp, xp, (gxz_true - gxz), shape)
plt.colorbar(shrink=0.7)
giplt.m2km()
plt.subplot(2, 3, 5)
plt.title("Difference y deriv")
plt.axis('scaled')
giplt.pcolor(yp, xp, (gyz_true - gyz), shape)
plt.colorbar(shrink=0.7)
giplt.m2km()
plt.subplot(2, 3, 6)
plt.title("Difference z deriv")
plt.axis('scaled')
giplt.pcolor(yp, xp, (gzz_true - gzz), shape)
plt.colorbar(shrink=0.7)
giplt.m2km()
plt.show()