code: def compute_qpi(self):
          
          kwargs = self.model_kwargs.copy()
          kwargs["radius"] = self.radius
          kwargs["sphere_index"] = self.sphere_index
          kwargs["center"] = [self.posx_offset, self.posy_offset]
          qpi = self.sphere_method(**kwargs)
          # apply phase offset
          bg_data = np.ones(qpi.shape) * -self.pha_offset
          qpi.set_bg_data(bg_data=bg_data, which_data="phase")
          return qpi
docs: Compute model data with current parameters
  
          Returns
          -------
          qpi: qpimage.QPImage
              Modeled phase data
  
          Notes
          -----
          The model image might deviate from the fitted image
          because of interpolation during the fitting process.