# Stope Section Coordinates

When you define the Stope Section boundary or a ground/truncation surface, a local X-Y coordinate system is used, where:

• The X-axis is horizontal and positive to the right (in the plane of the 2D section).
• The Y-axis is vertical and positive upwards (in the plane of the 2D section).

## Stope Section Orientation

The relationship of the Stope Section X-Y coordinate system to the 3-dimensional orientation of the stope you are modeling, is that you are looking at a top (bird's eye view) of the pillar. The stope sides (or abutments) then go into the page to some defined Pillar Height.

NOTE: For a Rectangular Pillar shape, the Pillar Length, and Pillar Width sides are aligned with the x-axis and y-axis, respectively. The Stope Section geometry is fully defined by the Pillar Length and Pillar Width in the Input Data dialog. Rectangular Pillar coordinates cannot be directly edited.

## Coordinate Values

The absolute values of the X-Y coordinates which you use to define the Stope Section boundary, is not important, except for the following cases:

• The absolute values of the X and Y coordinates of the Opening Section boundary, should have a similar order of magnitude. For example, if the X coordinates are small (near zero) then the Y coordinates should also be small. Or if the X coordinates are large, then the Y-coordinates should be large.
• If there is a very large difference in the order of magnitude between the X and Y coordinates, then numerical problems may result. For example, if X coordinates were small (near zero) and Y coordinates were very large (> 1 million), then numerical problems may occur with the analysis.

Except for these cases, you may define the Stope Section boundary coordinates anywhere in the X-Y plane, and this will not affect the results of the CPillar analysis.