1. The lines drawn on sections are merely strings of point data, that is the interpolator only considers the digitized points as structural data and ignores the segments.
     
  2. The cokriging interpolator used in GeoModeller is fully 3D and will attempt to honor all structural data inputs in the vicinity of the section. As a consequence the lines drawn on section may seem to be ignored by the interpolator where, in reality, it is providing the best fit possible given the data.
     
  3. By default the interpolator is set to have a degree of tolerance against the data to improve the stability of the geometries of the modeled surfaces. If you require the interpolator to be more exact (in the geostatistical sense).
    You may decrease the nugget effect in the Nugget Effect section of the Model Interpolation Parameters that is accessible via the parameters option of the Compute the Model wizard.