SM_from_OAM = spl.mask.ShorelineMask.from_Planform(
  OAP, contour_threshold=75)

SM_from_MPM = spl.mask.ShorelineMask.from_Planform(
  MP, contour_threshold=0.75)

fig, ax = plt.subplots(1, 3, figsize=(10, 5))

SM_from_OAM.show(ax=ax[0])
ax[0].set_title('Shoreline from OAM')

SM_from_MPM.show(ax=ax[1])
ax[1].set_title('Shoreline from MPM')

diff_im = ax[2].imshow(
  SM_from_OAM.mask.astype(float) - SM_from_MPM.mask.astype(float),
  interpolation=None, cmap='bone')
ax[2].set_title('OAM shoreline - MPM shoreline')
spl.plot.append_colorbar(diff_im, ax=ax[2])

plt.tight_layout()
plt.show()