Desurvey Validated Drillhole Data

To access this screen:

This screen, part of the Drillhole Importer console, is used to desurvey validated drillhole component data files (collars, assays, surveys etc.).

Validation isn't mandatory, and desurveying can be run against the imported data files without validation, or with existing validation errors. Results in this situation, however, can be unpredictable so it is recommended that you review each validation failure.

Various options are available to control the desurveying process (which is actually running HOLES3D).

Note: Whilst a typical drillhole importation scenario includes a Survey file, one is optional. If you decide to desurvey without a survey database, all data is assumed to be vertical, and this is highlighted when you actually desurvey the validated input data on the Desurvey screen.

You can update an existing drillhole file with new desurveyed information or create a new file. Once desurveying is complete, a summary displays, which can be exported.

Note: Drillhole Importer table columns can be resized.

To desurvey validated component drillhole tables into a static drillhole file:

  1. Complete the data import and validation stages of Drillhole Importer and display the Desurvey screen.
  2. By default, alphanumeric field widths are set to the width of the widest value. To override this and set a new field width, check the appropriate attribute(s) and set a new Width.
  3. Define the Drillhole Importer folder. This is the folder, typically a sub-folder of your active project, to host a desurveyed drillhole data file.
  4. Choose a Drillhole name. This is the file name that will be used to save a static drillhole file.
  5. If the chosen file name already exists, you can choose to either create a New file or Update the existing file.
  6. Specify how the desurveying is performed, using Desurvey options.
    • Decide if you want to Add samples for each survey record. When a hole sample is desurveyed the survey data (azimuth and dip) of the sample is used to locate the sample centre point in space. A desurveyed drillhole file contains a set of samples each with a calculated center point in XYZ world space.

      • Sometimes raw drillhole data tables to be desurveyed may contain more than one survey record within one sample, each with different azimuth and dips. Since a sample is by definition a straight line its location in space cannot be calculated using more than one survey record. If checked, desurveying will automatically divide up samples where more than one survey records lie within a sample.

        The samples are split in half until only one survey record lies within each sample. Therefore many samples may be created. This will cause extra samples to be created so that no sample contains more than one survey record within its FROM and TO values. For no extra samples to be created this option should be unchecked..

      • If unchecked and a sample does contain more than one survey record not all survey records will be taken into account. Traditionally this has been resolved by first compositing the samples to reduce their lengths.

    • Choose whether to Include survey direction from collar table.

    • Choose whether to Include sample end coordinates:

      • Check to include the X, Y and Z coordinates of the start and end of each sample in the desurveyed output file. Fields XSTART, YSTART, ZSTART, XEND, YEND and ZEND are created in the output file.

      • Uncheck to not output coordinate fields to the desurveyed file.

    • Choose the dip convention for the hole using Positive dip down.

      • If checked, positive dip values will represent downward dipping, down the hole. This is the default setting.

      • If unchecked dip values will represent an upwards dip.

    • Choose whether to Create drillhole intervals where data is missing.

      • If checked, the output file will include a record for every missing FROM / TO interval in the input sample files. The grades will all be set to absent data.

      • If unchecked the output file will not include FROM / TO intervals that were missing from the input sample files.

  7. Click Generate Drillholes to perform desurveying using the HOLES3D process.

    An Import summary displays on the right. If errors occurred during desurveying, they are listed here.

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