Geosoft - Exploring With Data

Displaying Drillhole Data More Effectively in 3D

For my first Roundup-inspired post, I picked a topic that every explorer I meet is interested in – working more effectively in 3D.

Displaying drill holes in 3D using DH-Plot > 3D Map is a convenient way to create a 3D map, complete with a legend, showing selected holes, topography, and two types of data.  Here, as may often be done in a 2D section, lithology has been plotted as a Rock pattern and gold assays are displayed as a Bar plot.  It is easy for this to become cluttered, making it hard to see significant characteristics in your data.

In order to start from a cleaner, less cluttered view of your data, try this instead:

1. Use DH-Plot > 3D Map to create the 3D map of the selected holes in the drillhole project, but leave the Data tab blank. For an even cleaner starting point, try turning off Plot Depth Ticks.

2. In the 3D Viewer, select the Add to 3D > Drillholes menu option.  Instead of plotting the geology as a Rock pattern, display only important geological intervals using discrete values in a Text band.

Discrete intervals in the Number bands option is also a good way to display significant ranges from assay results.

3. In order to display other discrete intervals from the same channel using the Add to 3D > Drillholes menu option, first rename the existing group.  Then you can toggle this layer on and off as you build your 3D data groups.

Now use the Add to 3D > Drillholes menu option to add more geology intervals or other downhole data.

4. Finally, add the Topography grid to help orient your 3D view relative to the surface.

Direct Gridding

New in Oasis montaj 7.3 and Target 7.3, and a fast and useful gridding algorithm: Direct Gridding.

Direct Gridding can be used to create a grid from highly sampled data without using any interpolation.  You can use the minumum, maximum, or mean value in the cell.  It is also a great way to make a grid from regularly sampled data. I used this to grid global topography from a large XYZ file.

3D View Orientation Buttons

New in 7.3 - quick 3D view orientation buttons in the 3D Viewer

Use these buttons to quickly view the 3D model from a cardinal direction, above or below, OR set your own inclination and declination viewing angle.

Reprojecting database coordinates with a script

Today I came across a Geosoft Knowledge Base article called How to reproject the X,Y coordinates in a database.  This is a handy little reference, as I used to do this task (or show others how to do this) on a regular basis. 

On one project, I set up a little script to do it for me. It was simple to create (learn more about scripting in this video!), saved time, and prevented the possibility of making small but costly errors if I were to do it manually each day.

Five Best Practices for Handling the Data Explosion

First there were megabytes, then gigabytes, and now terabytes, and petabytes. “A petabyte is the equivalent of a stack of DVDs stretching from here to the moon.” -- GigaOM Network and they are coming to an exploration office near you. Geosoft has five suggestions for best practices to help you handle the data explosion and improve exploration data management.

Where to start?

1. Clear the clutter. Identify which applications and formats are essential for your business and cull the rest. 
2. Find your coordinates. Ensure geographic coordinates are accurately recorded in the field, and managed as part of the data.
3. Use classifications. Using classifications, such as continent, country, state/region, project name, and data type to organize the data, makes the discovery of data more efficient.
4. Add descriptors. Establish and maintain a standard set of minimum required metadata fields for every dataset.
5. Make it flow. Streamline your workflows to move the data through the system from collection to collaboration and ensure that all users know where to find existing data and where to put new data.

You can read more on this topic in the latest issue of Earth Explorer – Handling the Data Explosion.   

What's New 2011 - 3D clipping

The Geosoft 2011 Update is now available. Look forward to a few new articles here about some of our favourite new features and functions.

Today's tip: In Oasis montaj, Target, and Extensions for ArcGIS, you can now use the 3D view clipping tools to clip all 3D object types, including: drillholes, symbols, grids and surfaces. You can also select and clip multiple groups at once.

3D vectors for contours created from a grid

Recently, some of us here at collaborated on a workflow to export topography contours to a 3D vector format.  We thought it'd be a useful one to share with our customers.  Here's how you go about it.

When creating the contours for the grid, modify the Options:

• Set the suppression density to 0 mm.
  This will ensure that the contour lines are closed.  
• For "hi-low annotation", select none.
• For label display, select no labels.
• Optionally define smoothing for the contours

Oasis montaj and Target

In Oasis montaj and Target, the contour option is found under Map Tools > Contour > Contour.  Once the contours are added to the map, select the contour group in the View/Group Manager Tool and export the selection to a 3D Shapefile through Map > Export > ArcView Shapefile.

MapInfo users can export the contour group to a TAB file and the Z value will be the value of the contour level.

Extensions for ArcGIS

In Target for ArcGIS, the contour option is found on the Target Surface toolbar. In Geochemistry for ArcGIS, the contour option is found in the Gridding menu.  Both Target for ArcGIS and Geochemistry for ArcGIS allow you to create the contours directly in Shapefile format.

Geosoft 3D Viewer and 3D DXF export

The 3D Shapefile can be added to the Geosoft 3D Viewer (Add to 3D menu > Imports).  The 3D Shapefile displayed in the 3D Viewer can be exported to a 3D DXF (Export menu > AutoCAD DXF File).

Recreating plots and replotting holes in Target

Recreate plot

Often you'll find it is necessary to recreate a plan map, section map or strip log with only a few changes to the parameters that were used to create the map.  This can be difficult to do from the menu options if the settings in the multi-tabbed dialogs have been changed while creating other maps.  However, the original settings used to create a map can be accessed and used to recreate the map, or create a new updated map.  Here’s how:

1. Select the collar database as the active table to ensure the map is linked to the drillhole project.
2. Make your map of interest the active window.
3. Select the Holes group in the View/Group Manager Tool.
4. Right-click on the map > select Recreate Plan (or Section, Strip Log).
   The Plan Map Parameters dialog will open with the parameters that were used to create that map.
5. You can adjust any of the parameters.
   If you do not want to overwrite the existing map, make sure you add a "Map Name Tag" on the Page Layout tab.
6. Click OK to recreate the map.

Replot holes

For Plan and Section maps, you can use the "Replot Holes" function from the DH-Plot menu to update the map.  This is similar to the above tip but the replot dialog has fewer parameters that can be changed for the active map because it only updates the groups and does not create a new map.

For example, this function could be used to plot proposed holes that were added to the project or to change the data being plotted along the trace.  

Data Quality using Profiles

When I receive a new point or line-based dataset, often my first action is to use Oasis montaj or Target to look at the channel profiles in a Geosoft database (after importing the data into a Geosoft database, if required).  This is a valuable way to check the data quality and get familiar with the data.

Profiles of the coordinate channels (x,y) help to quickly identify location errors from missing values, reversed x and y coordinates, or simple typos.  Line data coordinates usually have smooth and consistently increasing (or decreasing) profiles.

 

Profiles of the data can be used to look for strange values and noise. Selecting any suspicious locations in the profile window will jump to that location in the database table.

 

I often select the line header cell and use the Page Up and Page Down keys to scroll between adjacent lines in the database for a quick way to review the data.

If this data format is being collected regularly, then saving the database view (Database > Save Working View...) makes the review of data channels more efficient next time.

How to download SRTM topography data

SRTM (Shuttle Radar Topography Mission) are the most popular datasets on the Geosoft DAP Server.  These grids make a great base group on a regional scale map or a relief surface to drape other data on in 3D.  The entire dataset – 90m World or 30m US – is very large (originally, it was delivered on a stack of DVDs).  Using DAP, any chunk can be downloaded in a few easy steps.  Here’s how:

1. Using Seeker through Oasis montaj, Target, ArcGIS (with Target for ArcGIS or the Plugin for ArcGIS), or MapInfo (with the Geosoft Plugin for MapInfo), open Seeker.

2. Define the Area of Interest, by repositioning the red Area of Interest outline, double clicking on the longitude or latitude values to edit them, selecting a region from the list, loading an area of interest from a file (there are a number of supported formats), or refreshing from your open map (if applicable).

  

3. Optionally, narrow the results by adding text search criteria such as a keyword like “SRTM”.

4. In the Results for the Geosoft DAP Server, the SRTM World Elevation 90m and SRTM US Elevation 30m will appear (as long as they intersect with your area of interest).

Note that these data do not extend past 60N or 60S.  If you are looking for topography data in these regions, GLOBE DEM and SRTM30 Plus are also available on the Geosoft DAP Server.

5. Select the topography dataset.  Move to the Cart tab and adjust the download options to your preferences. This may include changing the format or reducing the resolution (often, the original resolution is desired so select the Do Not Resample option if you have selected several datasets).

6. Click Retrieve, and the topography for your area of interest will be downloaded to your Destination Folder.

If you are not using a Geosoft application or plugin, then the same datasets are also available from the Geosoft DAP Server web interfaces. Visit http://dap.geosoft.com/geodap or http://dap.geosoft.com/flamingo.