The appropriate x and y increment will be computed. If you wish to have the region divided into a 10 rows by 10 columns, simply enter 10 in the "NxN" field and click the "Set" button. The cell size of increment also defined in XY map units. The regional grid is defined as a rectangular box in XY map units. The dominant angle is the "mode" of the histogram, i.e., the orientation that has the longest line segments. The dominant angle of orientation for each regional grid cell can be posted above the rose diagram. The "length value" for a cell is the percent of the cell's length to the maximum length. Then, the maximum of these lengths is found. The total length of all lines inside a regional cell are totaled. Values can be posted that provide a relative length of lines in a regional grid cell. If a line crosses a subgrid cell, then the area of the subcell, or 1% of the regional grid cell, is summed as "area coverage" value and can be posted. This sub-grid is used to determine the percent of area coverage by lineaments of fractures.
Only the portion of a line lying within a cell is considered in these calculations.Įach regional grid cells is, in turn, subdivided into a series of 10x10 grid cells. The total length of lines within each cell is summed and a histogram is built based on the orientation of each line segment. The outlines of the grids can be seen in Figure 1. Lineament or fracture data in an overlay layer is subdivided into a series of regional grid cells. This feature analyzes line data from an overlay layer and generates rose diagrams illustrating orientation and coverage of the lineament features on a regional basis.