Creating GSF Surfaces from 3D Block Model Values - Mintec, Inc.

MSBasis: Creating GSF Surfaces from 3D Block Model Values
MineSight Basis procedure Generate GSF Top & Bottom (srf3db.dat) creates surfaces from 3D block model (file 15)
items.
This procedure will create surfaces based on either a single value or a range of values for up to five block model items, and
store the surfaces in a Gridded Surface File (GSF). It stores top and bottom surfaces, and can optionally store the thickness
between the two surfaces. This is useful for modeling geologic structures, including seams and other mineralized zones.
In the following example we create top and bottom surfaces for a single value (11) of a single item (SEAM1) in the block
model, and store the surfaces and thickness to the GSF items TOP, BOT, and THK.
A cross section of the block model is shown in Figure 1. Each block having a SEAM1 value is labeled with the value. Blocks
not having a SEAM1 value are not displayed.
Figure 1 A cross section of the
block model showing values
for item SEAM1.
ß Figure 1
The next step is to be sure your GSF contains the required items (Figure 2). You’ll need items in which to store the top and
bottom surfaces (TOP and BOT) and the thickness (THK). The Min and Max values of these items should cover the same
elevation range as the block model.
Figure 2 The GSF file prepared to
store the top and bottom surfaces
(TOP and BOT) and the thickness
between the two (THK).
ß Figure 2
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To create the surfaces, launch srf3db.dat from MineSight Compass (Figure 3).
Figure 3 The procedure on the MineSight Compass menu.
á Figure 3
The procedure consists of a single panel (Figure 4). Select the Item which will be used to define the surfaces (SEAM1) and
its Minimum and Maximum values. The min and max values can define a range, but in this example we’re choosing to
create surfaces at the top and bottom of all blocks having value 11. Then, select the items in your GSF model which will
be used to store the top and bottom surfaces (TOP and BOT) and the thickness (THK). The topo percentage item (TOPO)
must also be specified, to ensure that the GSF surfaces do not project above the current topo.
Figure 4 The srf3db.dat panel,
showing inputs to store TOP,
BOT, and THK of SEAM1 equal
to 11.
ß Figure 4
Hint
In Figure 4, you can specify up to five items to determine the surfaces. At least
one block must be found which meets all the conditions and has a TOPO percent
greater than zero. Otherwise the surfaces will have a ‘hole’ where they’re given
a missing value.
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Running the procedure produces two GSF surfaces as shown in Figure 5: one representing the TOP surface item (orange)
and one representing the BOT surface item (green) (Figure 5).
Figure 5 The TOP and BOT
surfaces from the GSF file,
representing the top and
bottom surfaces of blocks
with SEAM1 equal to 11.
á Figure 5
Figure 6 shows a 2D sectional view of the GSF TOP and BOT surfaces compared to the block model SEAM1 value.
â Figure 6
Figure 6 A cross section showing the SEAM1
block model item and the resulting top and
bottom surfaces.
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