Geological Data Files

What is a geological data file?

Geological data files contain integer values that indicate geology type for a regular three-dimensional grid.
Create an example geologyical data file by entering Create_example_data in the Matlab command window. The file will be saved as an XYZG ASCII file geological grid file.

Geological data files are needed for spatial data analysis and interpolation. Data interpolation treats each geology type independently to avoid the prediction of unrealistic particle-size distributions.

If there is no reason to treat each geological zone in independently, use a geological model containing identical geological indicators, e.g. ones.

File format:

Geology files recognised by the Particle-Size Toolbox come in these formats:
  • Geovariances Isatis binary format
  • XYZG ascii format
  • XYZG csv format
  • Matlab binary format

Isatis binary files:

Isatis binary files for geological data should be created from within Isatis using the following options:
    • Select 'File > Export > Binary File'
    • Select the geological variable by choosing 'Input File'.
    • Check the box 'Use the Isatis binary file format with header'.
    • Leave the 'Undefined Value in Binary File' empty. This is given in the file header.
    • Check that grid sorting is listed as +Z +Y +X (default setting)

Press 'Output Binary File' to export the geological data as a '.bin' or type binary file.


This is a 3D grid format that can be written by a wide range of programs, including Isatis, Surfer and GoCAD.
Data should be saved as a '.asc' ascii file containing 4 columns:
    • column 1: X co-ordinate
    • column 2: Y co-ordinate
    • column 3: Z co-ordinate
    • column 4: Geological indicator

WARNING: ASCII files are much larger than binary files! For geological grids with more than 10 million cells it is recommended to use binary format to save disk space.

Create an example geological model by entering Create_example_data in the Matlab command window.

XYZG csv format

The same as the ASCII format, but with commas between variables rather than spaces or tabs.

Matlab binary format

All geological files loaded into the PST are converted into .mat Matlab binary files and stored in each PST project directory in Data\ImportData.

Matlab geological files are very compact and contain the geological data matrix 'outvar' and a header structure 'header'. The header contains all the information about the geological variable, e.g. the variable name, matrix dimensions and how the file was created.