When dealing with a large number of logged structures, it is often desirable to get a comprehensible overview of their orientations.
The Stereonet plot provides this functionality, by projecting the three-dimensional global orientation of both linear and planar structures unto a two-dimensional canvas.
The Stereonet plot and it's options are only avilable for holes with collar data. See Collar Data for more information.
Error source: All global orientation angles are ill-defined if the sample was not oriented during scanning. Always proceed with caution when interpreting structural orientations.
The Stereonet plot is available as a tab nex to 3D Tomography and Concentrations Map:
Each plotted data point corresponds to one of the user-logged structures, with a position derived from it's Global Orientation.
Data Point Projections
The Stereonet plot in Insight employs a "pole" representation of structures with a lower hemisphere perspective, meaning that:
- Data point positions for linear structures are determined from their downwards-inclined direction vectors (just like their global orientations).
- Data point positions for planar structures are determined by their downwards-inclined normal vectors (in contrast to their global orientations).
To visually separate between linear and planar structures, the former are plotted with dots whereas the latter are plotted with squares.
These reference directions are then projected unto the two-dimensional canvas through either of two available projection techniques [Snyder, J. P. (1987). Map projections--A working manual (Vol. 1395). US Government Printing Office. Page 154 and 182]:
- Equal Angle (also commonly referred to as "stereonet" or "Wulff net")
- Equal Area (also commonly referred to as "Lambert azimuthal" or "Schmidt net")
The difference between the two techniques is illustrated in detail by comparing their resulting grid lines:
Visibility of Structures
Structures can be filtered for visibility based on their depth and type. By default, all of the logged structures for the current hole will be shown in the plot.
Filtering structures based on their type is done via the checkboxes found in the structure type lists to the right. Both entire structure categories and specific structure types can be made visible/hidden.
The structure type lists also serve as a legend: showing the symbol
(shape and color) for each structure type.
The two numbers in parenthesis are the number of structures (of the specific type) that are currently visible, and the total count within the hole.
Filtering Structures based on their depth is done by Selecting a Segment in the Preview area:
Finishing the depth based filtering is done by clearing the segment selection in the Preview area.
Displaying Structure Data
The details of a structure can be displayed by hovering over it with the mouse pointer. This structure is marked with an enlarged symbol. If there is no structure under the mouse pointer, then the coordinates of the mouse pointer are displayed.
Structures can be selected (see Structures) by clicking on their symbols. The selected structures are indicated with black edge around their symbols.