modtra

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MODTRA - create trace lines through a block model showing model attributes

Process Name	Menu Path	Link to Command Table
MODTRA	Model ribbon \| Data From Model \| Drillholes	Click here

Introduction
Files, Fields and Parameters
Notes
Example
Errors

Introduction

This process creates a regular grid of trace lines through a model.

These trace lines describe the continuity of a field value or set of field values in the model. Average values of all other model fields are calculated and associated with each trace segment.

How to use

The process simulates either a rectangular grid of drillholes, drilled through the model parallel to one of model axes, or a set of drillholes whose collars are defined in the optional &GRID file. The user specifies between one and five fields (*F1,.......*F5) which are used to terminate the simulated drillhole samples. If the value of any of the specified fields change, then the sample is terminated and a new sample started. The sample is written to a standard borehole format file, together with the average value of all numeric fields for that sample. If the model contains alpha fields then the dominant value of each field is also written to the output sample file. The dominant value is defined as the value which has the longest length. If the model contains a DENSITY field then the calculations of the average values and of the longest length are tonnage weighted.

The output drillhole file contains the standard drillhole fields - BHID, FROM, TO, LENGTH, A0, B0 plus all the non-model fields from the model file. The BHID is a numeric field, starting at 1 and increasing in steps of 1.

The purpose of creating the simulated drillholes is to plot a section through them. This will show the continuity of the *FN variable(s) in the section plane. A similar display could also be achieved using color fill of subcells. A model section plot without color fill will include subcell boundaries, which will display the continuity over a field or set of fields, but not as clearly as a drillhole section.

The specified fields *F1 - *Fn should have discrete values rather than being continuous; if a numeric field is specified such as an interpolated grade, then it is highly probable that the field value will change at every subcell boundary. If it is required to show continuity over a range of numeric values, then a 'flag' field should be created in the model with EXTRA prior to using MODTRA. For example if continuity is required within grade ranges 0-2, 2-5, 5-10, 10-20, 20+ then a flag value can be created in EXTRA for each of the 5 ranges. This flag field can then be specified as *F1.

Files, Fields and Parameters

Input Files

Name	Description	I/O Status	Required	Type
MODEL	Input model. Must contain the 13 standard model fields - XC, YC, ZC, XINC, YINC, ZINC, XMORIG, YMORIG, ZMORIG, NX, NY, NZ, IJK - plus at least one other field.	Input	Yes	Block Model
GRID	Optional input grid file defining the location of the simulated drillholes. It must contain ALL fields XG , YG , ZG, regardless of the PLANE parameter setting. This file must NOT include an alpha BHID field, as this would clash with the numeric BHID field created in OUT.	Input	No	Undefined

Output Files

Name	I/O Status	Required	Type	Description
OUT	Output	Yes	Drillhole File	Output holes file. Will contain the fields BHID, FROM, TO, X, Y, Z, LENGTH, A0, B0 plus all fields from input model file except the 13 standard model fields.

Fields

Name	Description	Source	Required	Type	Default
F1	1st field over which continuity is required within a sample.	MODEL	Yes	Any	Undefined
F2	2nd field over which continuity is required within a sample.	MODEL	No	Any	Undefined
F3	3rd field over which continuity is required within a sample.	MODEL	No	Any	Undefined
F4	4th field over which continuity is required within a sample.	MODEL	No	Any	Undefined
F5	5th field over which continuity is required within a sample.	MODEL	No	Any	Undefined
XG	Optional GRID field name holding X co-ordinate. Default is XG. Ignored if PLANE=3.	GRID	No	Numeric	XG
YG	Optional GRID field name holding Y co-ordinate. Default is YG. Ignored if PLANE=2.	GRID	No	Numeric	YG
ZG	Optional GRID field name holding Z co-ordinate. Default is ZG. Ignored if PLANE=1.	GRID	No	Numeric	ZG

Parameters

Name

Description

Required

Default

Range

Values

PLANE

Drillhole orientation. Default (1).

Option	Description
1	- XY. A grid of vertical holes is created.
2	- XZ. A grid of horizontal holes is created, running from North to South.
3	- YZ. A grid of horizontal holes is created, running from East to West.

1,3

1,2,3

XORIG

X co-ordinate of collar of first drillhole. Default is model X origin plus half a parent cell X dimension. Ignored if PLANE=3 or GRID specified.

Undefined

YORIG

Y co-ordinate of collar of first drillhole. Default is model Y origin plus half a parent cell Y dimension. Ignored if PLANE=2 or GRID specified.

Undefined

ZORIG

Z co-ordinate of collar of first drillhole. Default is model Z origin plus half a parent cell Z dimension. Ignored if PLANE=1 or GRID specified.

Undefined

XSPACE

Spacing in X between drillholes. Default is the parent cell X dimension. Ignored if PLANE=3 or GRID specified.

Undefined

YSPACE

Spacing in Y between drillholes. Default is the parent cell Y dimension. Ignored if PLANE=2 or GRID specified.

Undefined

ZSPACE

Spacing in Z between drillholes. Default is the parent cell Z dimension. Ignored if PLANE=1 or GRID specified.

Undefined

NUMX

Number of drillholes in X direction. Default is the number up to the model X limit. Ignored if PLANE=3 or GRID specified.

Undefined

NUMY

Number of drillholes in Y direction. Default is the number up to the model Y limit. Ignored if PLANE=2 or GRID specified.

Undefined

NUMZ

Number of drillholes in Z direction. Default is the number up to the model Z limit. Ignored if PLANE=1 or GRID specified.

Undefined

MISS

Missing cells treatment. Default is (0)

Option	Description
0	Where no model cell or subcell exists, no drillhole sample will be created.
1	Where no model cell or subcell exists, drillhole sample will be created with missing values.

Undefined

Print flag. Default (0). 0 - minimum output. 1 - summary of percentage complete and number of holes written.

Undefined

Notes

Having defined a plane, only two of the parameters @XORIG, @YORIG, @ZORIG will apply. For example, if @PLANE = 3, (YZ) then @XORIG will be ignored. Similarly for @XSPACE and @NUMX.
The dominant value of an alpha field is calculated for each drillhole sample as that value with the greatest length (tonnage weighted if there is a DENSITY field in the model). In order to preallocate accumulators it is assumed that there will be a maximum of 40 discrete values for any alpha field. If during the course of calculating the dominant value within a sample, a 41st value is found, then the value with the smallest current length will be dropped from the accumulators.

Example

This example will create a rectangular grid of drillholes drilled horizontally through the model from east to west. The spacing in the vertical Z direction between holes is 15 m (possibly representing the bench height) and 20 m spacing in the Y (north-south) direction.

!MODTRA

&MODEL(MODEL1), &OUT(HOLES), *F1(ROCKTYPE), F2(STRAT), @PLANE=3, @YORIG= 100, @ZORIG=200, @YSPACE=20, @ZSPACE= 15

Error and Warning Messages

Message	Description	Solution
>>> Fatal Error: in ffffffff file <<<	Where ffffffff is either MODEL or OUT. The program found an error on trying to access the file you specified as the ffffffff file.	Check that the file name is correct and that it exists.

>>> Fatal Error: in a field in ffffffff file <<<	where ffffffff is either MODEL or OUT. The program found an error on trying to access one of the fields in the file you specified as the ffffffff file.	Check that the file contains the compulsory fields (e.g. the 13 standard model fields if it is the MODEL model file). Also check that they are of the correct type (Alpha/Numeric, Explicit/Implicit).

>>> Fatal Error: F1 field not in MODEL file <<<		Check that the specified *F1 field exists in the input MODEL file.