Drill hole DTM intersection

You can use this function to find the points of intersection between drillholes that are stored in the geological database, and Digital Terrain Models (DTMs). For example, you might need to extract samples for geostatistical analysis. You can extract these samples by defining the zone of interest using one DTM to represent the upper surface and another DTM to represent the lower surface of the geological unit.

To run this function: Choose Database > Analysis > Drillhole DTM intersection, or Surfaces > Advanced options > Drillhole DTM intersection, or...

In the Function Chooser, type DRILL HOLE INTERSECT DTM, and press ENTER.

This function is an effective method of assigning geology codes to samples after the sample data has been stored in the database. The results of this function are the intersection points between the selected drill holes and the DTMs, expressed in terms of depths from the drill hole collar. The intersection details, that is, hole ID and depths, are written to a log file for future reference. You can also save the intersection details to an interval table in the database for future use by other database processing functions.

Note: If you want to save the intersection points to a table in the database, the drillhole trace must be completely contained in the bounds of the DTM or DTMs used in the function. The intersection depths must be sorted into pairs that represent depth_from and depth_to values for storing in the interval table. If the drill hole is not completely contained within the bounds of the DTM or DTMs, it is not possible to determine with certainty which of the intersection points represent depth_from values and which represent depth_to values.

Tip: If you plan to save the intersection points to the database, you should create a separate table for storing the intersection details. Where these intersection points are the result of interpretation, it is better to not mix them with the actual measurements of the drill hole from the logging operation.

Fields on the Drill hole intersect DTM form

Field	Description
Intersection type	The type of intersection. Options are: Above one dtm: Finds the intersection point(s) between the drill holes and one DTM and assigns a geology code to all parts of the drill holes that are above the DTM. Below one dtm: Finds the intersection point(s) between the drill holes and one DTM and assigns a geology code to all parts of the drill holes that are below the DTM. Between two dtms: Finds the intersection point(s) between the drill holes and two DTMs and assigns a geology code to all parts of the drill holes that are between the two DTMs. For a DTM created on the XY plane, the part of a drillhole considered 'above' a DTM is the portion that physically protrudes from the top of DTM. The part of a drillhole considered 'below' a DTM is the portion that physically protrudes from the underside of the DTM. For DTMs created on other planes, the part of a drillhole considered 'above' the DTM is the portion protruding in the 'towards' direction of the plane (along the section's Z-axis towards your viewpoint). For example, if a DTM was created using the current view plane and the active view plane was: a vertical plane resulting from VERTICAL SECTION LOOKING EAST, then the 'towards' direction is to the West and the part of a drillhole that physically protrudes towards the West of the DTM is considered 'above' the DTM. a vertical plane resulting from VERTICAL SECTION LOOKING WEST, then the 'towards' direction is to the East and the part of a drillhole that physically protrudes towards the East of the DTM is considered 'above' the DTM. a vertical plane resulting from VERTICAL SECTION LOOKING NORTH, then the 'towards' direction is to the South and the part of a drillhole that physically protrudes towards the South of the DTM is considered 'above' the DTM. a vertical plane resulting from VERTICAL SECTION LOOKING SOUTH, then the 'towards' direction is to the North and the part of a drillhole that physically protrudes towards the North of the DTM is considered 'above' the DTM.
Define the first DTM
Location	The location of the first DTM. This is usually the upper DTM.
[Refresh]	Loads the Object ID and Trisolation ID drop-down lists with the objects and trisolations of the DTM. In Surpac 6.6.1 and earlier versions, when you selected a DTM in the Location field, Surpac would load the DTM, validate it, and then load the Object ID and Trisolation ID drop-down lists. You could not interact with the form until the process was complete, which could be a long time for some large DTMs. Now, Surpac does not load the drop-down lists until you click the Refresh button, and validation does not occur until you click Apply in the form. Any validation errors are reported in the Message window.
Object ID	The objects of the DTM that you want to use for intersection. You can type the Object ID or select it from the drop-down list, if the list is loaded.
Trisolation ID	The trisolations of the object in the DTM that you want to use for intersection.
Define the second DTM
Location	The location of the second DTM. This is usually the lower DTM.
[Refresh]	Loads the Object ID and Trisolation ID drop-down lists with the objects and trisolations of the DTM.
Object ID	The objects of the DTM that you want to use for intersection. You can type the Object ID or select it from the drop-down list, if the list is loaded.
Trisolation ID	The trisolations of the object in the DTM that you want to use for intersection.
Define the database table name
Save results to database	Selected: The results of the intersection are saved to an interval table in the database. Note: After you apply this form the Define field to update form is displayed so you can identify the field name that you want the intersection code saved to. Cleared: The results of the intersection are not saved.
Table name	The name of the interval table that the results are saved to.
Code	The geology code that you want to use to identify the intervals of the drillholes that are above or below the DTM, or between the DTMs.
Define results file
Report file	The location of the file that will contain the results of the intersection.
Format	The file format the results of the intersection are stored in. The options are; .not, .csv, .htm, .html, .rtf, .pdf, .ps, and .log.

After you apply the Drillhole intersect DTM form, the Define field to update form is displayed. You can use this form to select the field name in the drillhole table that will contain the results of the intersection.

Fields on the Define field to update form

Field	Description
Table	Display only. The table that you selected to store the results of the intersection. Note: The table that is selected for saving the intersection results must be an interval table as the intersection points must be saved in the depth_from and depth_to fields.
Field	The field in the table in which you want to store the results of the intersection.

Field

Description

Table

Display only. The table that you selected to store the results of the intersection.

Note: The table that is selected for saving the intersection results must be an interval table as the intersection points must be saved in the depth_from and depth_to fields.

Field

The field in the table in which you want to store the results of the intersection.

After you apply the Define field to update form, the Define query constrains form is displayed. You can use this form to constrain the data that is processed by the DRILL HOLE INTERSECT DTM function.

Fields on the Define query constraints form

Field	Description
Field Name	The name of the field in the table to constrain by.
Operand	The operator that you want to use to constrain the data in the field. Options are: < : less than. <= : less than or equal to. > : greater than. >= : greater than or equal to. <> : not equal to. = : equal to.
Constraint Value	The numeric value you want to use to constrain the field values.
Load	Allows you to select a constraint that you have previously saved.
Save	Saves the constraint you have entered.

Output

A log file is created to contain the results of the intersection between the drill holes and the DTMs. This log file contains the hole IDs and the depth values sorted into depth_from and depth_to values. If a drill hole has multiple intersections with the DTMs they are all included in the log file.

If you elected to save the intersection results to a database table, and if the drill hole is completely contained within the bounds of the DTMs, the intersection results are saved to the specified interval table in the database.

Troubleshooting

Message Description

The selected DTMs were not created on the same plane. The DTMs used must be created on the same plane. Choose different DTMs, recreate the DTMs on the same plane, or transform the data in one of the DTMs to match the plane of the other.

Message	Description
`The selected DTMs were not created on the same plane.`	The DTMs used must be created on the same plane. Choose different DTMs, recreate the DTMs on the same plane, or transform the data in one of the DTMs to match the plane of the other.
`Drill hole "hole id" is outside DTM - can't save results to table`	This message is displayed if you intend to save the intersection results to a database table and the hole is not completely contained within the bounds of the DTMs. This message will also be found in the log file. This is a warning message only and does not stop the function.

Drill hole "hole id" is outside DTM - can't save results to table

This message is displayed if you intend to save the intersection results to a database table and the hole is not completely contained within the bounds of the DTMs. This message will also be found in the log file.

This is a warning message only and does not stop the function.