DTM triangles outside a 3DM

You can use this file-based function to create a new DTM by intersecting the triangles of a 3DM and DTM. This function saves the triangles of the DTM which are outside the 3DM. You can save the line of contact between the DTM and 3DM to a specified string number. For example, you could use this function to find the surface area of a proposed pit surface which is outside an ore body.

To run this function: Choose Solids > Solids tools > File Intersection > Clip DTM outside a solid, or...

In the Function Chooser, type TRISOLATION FILE 3DM/DTM OUTSIDE, and press ENTER.

Fields on the Create new 3DM from DTM triangles outside a solid form

Field	Description
Define the outersected surface
Location	The file location for the surface that is outersected.
Id number	The Id number of the surface that is outersected.
Object range	The object range for the surface that is outersected.
Trisolation range	The trisolation range of the surface that is outersected.
Retain other trisolations	Selected: Other trisolations of the outersected file are copied to the results file. Cleared: Other trisolations of the outersected file are not copied to the results file.
Define the outersecting solid
Location	The file location of the solid used for outersection.
Id number	The Id number of the solid used for outersection.
Object number	The object number of the solid used for outersection.
Trisolation number	The trisolation number of the solid used for outersection.
Define the result file to be created
Location	The file location where you want to save the result file.
Id number	The Id number of the result file.
Object number	The object number of the objects in the result file.
Contact string	The string number for the line of outersection between the solid, or solids, and surface. If you do not want to save the line of contact set the string number to 0.

Result

The result of this operation is a series of N distinct DTMs stored as trisolations 1 to N of the Object number. The neighbour list of each of the trisolations is set automatically. The line of contact is saved with the specified string number.

This function works without errors in the majority of cases. However, for certain data sets you might find that the function either stops with a warning message during processing or produces a result which is not closed. These errors occur because the function has had difficulty in creating new triangles along the line of intersection of the two trisolations to join them together smoothly. These problems arise because of one of the following situations:

a vertex of a triangle of one of the trisolations is very close to a vertex of a triangle of the other trisolation
a vertex of a triangle of one of the trisolations is very close to an edge of a triangle of the other trisolation
an edge of a triangle of one of the trisolations is very close to an edge of a triangle of the other trisolation

If you see this error your should display the two trisolations in Graphics and examine the region (or regions) where the two trisolations intersect to check for these conditions, and make appropriate adjustments to correct the problem. After making some changes, and saving them, you can attempt to perform the intersection again.

An alternative is that you could use String Maths to shift all the points of one of the trisolations by a small amount, for example, at the second or third decimal place, and attempt the intersection again.

Troubleshooting

Message	Description
`There is no region of intersection between the two trisolations`	No result will be created since an intersection cannot be found.
`The neighbours of the first trisolation have not been set`	You need to set the neighbours and the directions for the two trisolations using the Validation functions from the Solids menu .
`The neighbours of the second trisolation have not been set`	You need to set the neighbours and the directions for the two trisolations using the Validation functions from the Solids menu .
`The first trisolation is not closed`	You need to set the neighbours and the directions for the two trisolations using the Validation functions from the Solids menu .
`The second trisolation is not closed`	You need to set the neighbours and the directions for the two trisolations using the Validation functions from the Solids menu .
`The direction of the first trisolation has not been set`	You need to set the neighbours and the directions for the two trisolations using the Validation functions from the Solids menu .
`The direction of the second trisolation has not been set`	You need to set the neighbours and the directions for the two trisolations using the Validation functions from the Solids menu .
`The maximum number of consolidations has occurred`	More than 50 consolidation restarts have occurred. It is recommended that you shift the position of triangle vertices of one of the trisolations slightly.
`The line of intersection is not closed`	It is a prerequisite of the trisolation intersection functions that the line of intersection between the two trisolations is closed. If the line of intersection is not closed, the intersection cannot be performed.
`Fatal retriangulation error Fatal error in calculations module`	It is recommended that you shift the position of triangle vertices of one of the trisolations slightly.
`Extent of data is too large to give accurate results with current settings`	The spread of the data is too large to give accurate results with the current settings of the sensitivity parameters in the consolidation module. To comply with the current settings (that is, the minimum intersection segment length of 0.001 units), the spread of the data must not exceed 100000 units.

Note: If either of the input trisolations has validated=false, then the function will stop with an error message. If either of the input trisolations has not had the validated flag set then the WARNING: 3DM NOT YET FORMALLY VALIDATED form will be displayed.