Merge Voxels

Use the Voxel > Utilities > Merge Voxels menu option (geogxnet.dll(Geosoft.GX.VoxUtils.MergeVoxels;Run)*), to merge two existing numerical voxels to create a new voxel.

Merge Voxels dialog options

Voxel 1

Select the first voxel file to be merged.

Script Parameter: MERGE_VOXELS.VOXEL1

Voxel 2

Select the second voxel file to be merged.

Script Parameter: MERGE_VOXELS.VOXEL2

Output merged voxel

Select the name for the merged voxel file.

Script Parameter: MERGE_VOXELS.OUTPUT_VOXEL

Horizontal cell size

Optionally specify the horizontal cell size of the new voxel. If this is left blank, the output voxel cell sizes will be set to the minimum X and Y cell sizes in the Input voxel 1. The output Z cell sizes are set based on the original Z cell sizes in Input voxel 1, extending up and down as necessary, using the top and bottom Z cell size.

Script Parameter: MERGE_VOXELS.CELL_XY_SPACING

Application Notes

*The GX tool will search in the "...\Geosoft\Desktop Applications \gx" folder. The GX.Net tools, however, are embedded in the geogxnet.dll located in the "...\Geosoft\Desktop Applications \bin" folder. If running this GX interactively, bypassing the menu, first change the folder to point to the "bin" folder, then supply the GX.Net tool in the specified format.

Horizontal Cell Size

If the horizontal cell size is not specified in the dialog, then the minimum of the X spacing or Y spacing of the first voxel is used as the spacing parameter.

Vertical Cell Size

The vertical spacing of the layers in the output voxel is based on the first input voxel. The top and bottom spacing of the first voxel is used for locations above and below the first voxel.

Merge Description

The first voxel will generally be resampled to match the horizontal spacing requirements, it will not be resampled if the horizontal spacing is equal to the horizontal spacing in both X and Y directions and the calculated resampled origin is equal to the current voxel origin.

The second voxel is then reprojected and resampled into the first voxel's coordinate system, and blending occurs where the volumes overlap.

The Blending Method

Once resampling of the initial voxel is completed, the resampled voxels consist of two sets of horizontal layers or slices, some of which may overlap, and so must be merged. The Blend method uses a blending function over the area of overlap so that transition across the overlap from one voxel to the other is smooth. The edge of the overlap zone typically has two parts; one bordering on voxel 1, and one bordering on voxel 2. The weighting at any location is calculated using the relative proximity of the two edges. For instance, if a position is equidistant between both edges, its value is the average of the grid values found at that point. A cosine function is used which varies smoothly from 0 to 1, and takes on a value of 0.5 at positions at the midpoint of the overlap.

Singular Points

Where the edges of Voxel #1 layer and Voxel #2 layer cross at a single point, the blending scheme breaks down, since by definition both grids are full owners of the point. In this case the average of the two grid’s values at the point is used.

Overlap

The Merge Voxels tool now checks the spatial extents of both voxels to see if they overlap, and informs you when they do not. Intersecting voxels occur when:

  • The voxel bounds (the cube around them) intersect, or
  • The voxel values intersect.