Clip solid below a DTM

You can use this file-based function to create a new 3DM by intersecting the triangles of a 3DM and DTM. This function saves the triangles from the 3DM that are below the DTM and the triangles from the DTM that are inside the 3DM to a new DTM file. You can also save the line of contact between the 3DM and DTM to a string file. For example, you could use this function to determine the volume of an ore body below a proposed pit surface.

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

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

Fields on the Create a new 3DM from 3DM triangles above a DTM surface form

Field	Description
Define the solids to be intersected
Location	The file location for the solid, or solids, that are intersected.
Id number	The Id number of the solid, or solids, that are intersected.
Object range	The object range for the solid, or solids, that are intersected.
Trisolation range	The trisolation range of the solid, or solids, that are intersected.
Retain other trisolations	Selected: Other trisolations of the intersected file are copied to the results file. Cleared: Other trisolations of the intersected file are not copied to the results file.
Define the intersecting surface
Location	The file location of the surface used for intersection.
Id number	The Id number of the surface used for intersection.
Object number	The object number of the surface used for intersection.
Trisolation number	The trisolation number of the surface used for intersection.
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.
Use intersected object ID number	Selected: The object numbers of the intersected objects are used as the object numbers in the result file. Cleared: The Object number field is used to name the objects in the result file.
Object number	The object number of the objects in the result file. This field is only available when the Use intersected object ID number field is cleared.
Contact string	The string number for the line of intersection between the solid, or solids, and surface. If you do not want to save the line of contact set the string number to zero.

Ouput

The result of this function is stored in the object defined by the Object number. If there is no area of intersection between the triangles of the two trisolations and the input 3DM trisolation is below the DTM then the result will be the input 3DM trisolation (as long as at least part of the 3DM lies inside the boundary of the DTM when in plan view).

The neighbour list of the trisolation is set automatically and the direction of the trisolation is set to SOLID by default. The line of contact is saved with the string number requested.

This function has proved to be robust in the vast 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 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`	The line of intersection between the two trisolations must be closed, or the trisolation intersection functions 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.