GMS:Horizons to 3D Mesh

The following steps illustrate how to use the Horizons method to create 3D Mesh stratigraphy.

1. Create/Import Inputs - There are two main types of inputs for the horizons method:
   1. Boreholes - Boreholes can be created by importing borehole data by using the Text Import Wizard, importing sample data after boreholes already exist, or using the borehole tools to manually enter the boreholes. Once a borehole has been created it can be edited in the Borehole Editor or by using the borehole tools. Also an existing borehole can be copied. Boreholes can be locked to prevent them from being edited.
   2. TINs - TINs can be created 3 different ways in GMS: manually entering the vertex locations and triangulating, converting a different GMS data type to a TIN, and copying a currently existing TIN. (See Creating TINs)
2. Assign Horizon IDs - The term “horizon” refers to the top of each stratigraphic unit that will be represented in a corresponding Solid, HUF unit or Material Layer. Horizons are numbered consecutively in the order that the strata are “deposited” (from the bottom up). Horizons can be assigned to both Boreholes and TINs. (See Horizons)
3. Create Primary 2D Mesh - A 2D mesh is needed to be used as a projection for the resulting 3D mesh. A 2D mesh or a meshing coverage needs to be created and selected as the primary mesh. The 2D mesh defines the boundary of the 3D Mesh. Also, the meshing options assigned to primary coverage controls the elements of the 3D Mesh that is created. (See Creating 2D Meshes)
4. Setup additional optional inputs - Two additional options exist to help constrain and provide user intervention in the Horizon modeling process. The two options are to create borehole cross sections or a horizon conceptual model.
   1. Including Borehole Cross Sections
   2. Horizon Conceptual Model
5. Run the Horizons Wizard - Select the Horizons->3D Mesh command in the Borehole or TIN menu.

Horizon -> 3D Mesh Algorithm

When the Horizon command is executed the horizons specified on the borehole contacts or TIN nodes are converted to a set of scatter points with one data set for each horizon. The scatter points are then used to interpolate a surface for each horizon. Starting with the lowest numbered horizon, the surface is extruded down to create a set of elements in a 3D Mesh. The surface corresponding to the next horizon is then extruded down to fill in the space between that surface and the previous surface. This process is repeated for each surface. At each step, a set of elements are created for the current horizon and all previously defined elements are subtracted from that layer, resulting in an incremental buildup of the stratigraphy from the bottom to the top. The entire process results in a 3D Mesh with each horizon layer represented by a Material Zone.

File:Hor TINs.gif

TINs used to create 3D Mesh below

File:Hor 3DMesh.gif

3D Mesh created via the horizons method