Geosoft - Exploring With Data

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.

Can I Delete That File?

Geosoft stores all kinds of information in files and datasets (a dataset is a collection of related files). Some of these files are very important and should not be deleted except with extreme caution - like GI (Grid Information) files which store Coordinate Systems and other important details.

Some other files are temporary and I am often asked by users about which file types are safe to delete at the end of a project.  Here's a few from my list.

• _filename.ext -- File names that begin with an underscore are usually temporary files that are recreated when the function is re-run, such as gridding and contouring. One exception to watch for: ITR colour files for geochemical database channels (e.g _Cu.itr).
• i0, i3, i4, o0, o3, o4 -- These are import and export templates.
• GD~ -- This file is a temporary database file. It often disappears when the GDB is closed.
• INI -- Configuration settings.  Be careful not to delete custom INI files in Target and Target for ArcGIS.
• GM -- Geosoft MAP extension for Geosoft's MapInfo plugin.
• MDF -- Map definition file, used in map creation.
• LOG -- Log file or general report, ofen related to imports in Target and Target for ArcGIS.

Geographic Channel Formats

A question of how to georeference a raster image was recently raised in our Geonet forum.  There's an FAQ on How To: Warp or Georeference a Grid or a Database that provides some basic information on georeferencing.

This question also reminded me of a related topic: Using numeric channel formats in Geosoft databases (*.GDB) to convert from geographic number formats (DD.MM.SS.ssss) to decimal degrees (DD.dddd) or vice versa.

Here's how you can simply convert coordinates between these two common formats:

1. Create a new channel and set the display format to Geographic. 

 

2. Enter the Long and Lat coordinates of your point(s).

 

2. Right click on the channel header and select Edit...

3. Change the format to Normal and set Decimals to 6, then click OK.  Do the same for the other coordinate channel.  The coordinates are now in decimal degrees.

 
 
 

 

 

Create a polygon (*.PLY) from a shapefile (*.SHP)

In Target and Oasis montaj, sometimes you need to create a polygon file for windowing (i.e. windowing a grid to a polygon to make a new smaller grid) or masking (i.e. applying to mask to a database channel, or hiding a map group outside a polygon boundary). 

The first step is creating the polygon *.ply file.  If you are starting with an ESRI Shapefile, [you can import the Shapefile to a map, and use Create PLY File from Map Group. However, if the Shapefile contains polylines, rather than closed polygons, or if there are many items in the map group and editing would be required to isolate the polygons] then you can “blow up” a polygon shapefile when you import it to a Geosoft database.  This means that you will have a point for every polygon vertex or node, instead of just a record for the centre of the polygon [or polyline]. 

First, import the Shapefile to a new database using Database > Import > ArcView Shapefile(s).  In the ArcView Shape File Import dialog, set Import data to to "New database with shape database(s)".  When the import is complete, you will see a new {filename}_Shapes.gdb, where each polygon will be stored in a separate line in the database.

[To create the *.PLY file, export to an XYZ file and change the line references to poly tags:

poly 1
-17338.70    52620.96
-10705.64   -13104.83
-13508.06   -12096.77
-31552.41    53427.41

And remember to add the coordinate system information if you are working in multiple coordinate systems.]

Copy and Paste

Oasis montaj and Target maps are easy to share and incorporate in reports and presentations.

You can copy a map directly into Microsoft Word or PowerPoint.

1. While in Shadow Cursor mode, right click on the map and select Copy.
2. In Word or PowerPoint, select Paste Special (instead of Paste), and choose Picture (Enhanced Metafile).

You can also copy text (including font and formatting) from a Microsoft document to a Geosoft Map.

1. Select the text and choose Copy in your Microsoft document
2. In your Oasis montaj map, select Paste.

The new group is also an EMF (enhanced metafile) so it can be resized but not edited.

 

Oasis montaj and Target Hot Keys

Geosoft Oasis montaj and Target have a number of useful hot keys and shortcuts to improve efficiency when navigating on a map.  My favourite hot keys for working with a map are a combination of F and B.  F for "Zoom to full map" and B for "Zoom box". 

Other handy hot keys:

• Alt+C or the Escape key puts you back to Shadow Cursor mode
• S will zoom to a selected group. This is really useful if you have added a group to the map, but it didn't appear in the Data View.

You can configure or reset hot keys through the GX menu option Map Settings > Configure Map Shortcut Keys.

A full listing of shortcuts and other tips can be found in the Oasis montaj Quick Reference Card or Target Quick Reference Card.

Creating a Target List of Anomalies

We have already described how to dynamically link maps to other maps, database lines and profiles (see Linking Maps and Data).  The shadow cursor and data linking tools can also be used when working in Oasis montaj or Target to select anomalies and create a list of targets in a database. 

 

You can build a list of targets or anomalies from database profiles.  Simply select the anomaly in the profile window and right-click to access the context menu.

 

 

"Select Target..." will create a new group in the database (groups are similar to lines).  The default name is "Targets".  This can be easily changed, allowing multiple anomaly lists to be created.  Other database channels can be included along with the picked target location. 

 

 

The option to immediately plot a symbol of the location on the map is available too.  This is useful when using the database and map together with the Shadow Cursor Data Linking Tool, allowing you to pick target locations while seeing which targets have already been selected.

 

Pick as many targets as you like by selecting lines and right clicking on the profiles. Then review the list in the database. 

 

 

Later on, you can subset the group to create a new database or create new symbol plots using the associated channels.

Colour Bars and Group Names

In the upcoming version 7.2 release, groups names have been extended (from 31 characters to 1024 characters!), so you will see the full file name in the View/Group Manager Tool.   If you hold your mouse over the grid, you will also see the path to that file.

Tip: If you are resizing or moving a floating tool like the View/Group Manager and you do not want it to dock to the Oasis montaj workspace area, just hold down the Ctrl key while you are repositioning the tool.  This works for Geochemistry graphing tools like Histogram and Scatter Plot as well.

The longer group names are visible in the Colour Bar utility as well, which is handy when a map contains numerous grids or shaded grids.

To add more depth to your colour bar, try using the Secondary AGG/layer. The secondary, or shaded colour scheme, is blended horizontally within each colour of the primary colour scheme.  The effect is shown below.