3D Surface - External Data

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EQuIS 7  >>  EnviroInsite > External Data >

3D Surface - External Data

This routine generates 3D surfaces from point data stored in text files. Each record has the X-Y-Z coordinates and a data value. The files can be comma-delimited or space-delimited. The control options are the same as the 3D surface options used in interpolating measured data from a database.

 

To create a 3D surface using external data, click Plot> External Data from the main menu and select 3D Surface. The Surface XYZ dialog box opens. Modify the properties on the Query tab, Format tab, Options tab, Grid tab, Interpolation tab, and Image tab as desired. Click the OK button to save changes.

 

Query Tab

 

50146-query_3d_surface_external_data

 

 

Format Tab

 

50146-format_3d_surface_external_data

 

Options

 

50146-options_3d_surface_external_data

 

 

Grid Tab

 

50146-grid_3d_surface_external_data

 

 

Interpolation Tab

 

This tab allows the user to select the interpolation scheme and the parameters of the interpolation method. The correct selection of interpolation parameters is critical to generate contours that accurately reflect the field data and our expectations of how the values vary between the measured data points. The default parameters are frequently adequate, although some improvement can be anticipated through trial and error. There is no single, objectively optimal set of interpolation parameters. Different methods and parameters work best for different data sets.

 

50146-interpolation_3d_surface_external_data

 

Kriging Parameter

 

The kriging routines are derived from the kt3d routine of the Geostatistical Software Library (GSLIB) authored by Clayton Deutsch and Andre Journel (www.gslib.com).

 

50146-kriging_param_3d_surface_external_data

 

 

The reference GSLIB: Geostatistical Software Library and Users' Guide is highly recommended. The following equations are the spherical semivariogram models used by EnviroInsite for an isotropic system, where h is the lag, c is the sill, and a is the (practical) range.
(Source: Introduction to Geostatistics and Variogram Analysis, available here).

50120-spher_semivario_models_3d_contour

 

For anisotrophic systems, h/a in the previous is calculated as

50120-anisotropic_systems_3d_contour

 

 

Natural Neighbor Parameters

 

The natural neighbor interpolation makes use of an adapted version of the public domain natural neighbor code developed by Pavel Sakov of CSIRO Marine Research.

 

50146-natural_neighbor_params_3d_surface_external_data

 

 

Image Tab

 

50146-image_3d_surface_external_data