OR/18/010 Glossary

Terrington, R L, Thorpe, S. 2018. Post-calculation checks of GSI3D Models V2. British Geological Survey Open Report, OR/18/010.

Envelope	Defined here as the extent of a geological deposit in plan view (2D): forming a distribution map of the particular unit, a presence — absence map. May include an area of outcrop, subcrop or a combination of both
Grid	An exported surface or thickness as a gridded object with a specified cell size
GSI3D	The Geological Surveying and Investigation in 3-D software and methodology
Helper	A sections used to constrain the calculation in areas of few sections or thin units such as Alluvium or Head
Section	Defined here as a vertical x, z plane attributed with correlation lines
Surface	Base or top of a geological unit exported as a grid or TIN
TIN	Triangular Irregular Network. GSI3D exports TINs in Indexed Triangle Mesh format (VRML97)
Triangulation	A form of interpolation (Delauney) that uses TINS in GSI3D to form the base and top surfaces of a unit
Unit	A geological unit is a particular geological deposit that has been identified and mapped out during a GSI3D project. A unit is defined by its basal surface in sections and an envelope of its lateral extent. The top of the unit is back calculated during