It is now possible to create a map of peaks and depressions from a grid file in Surfer. This new layer type identifies the peaks and depressions in the grid by drawing a polygon around these areas. This is a closed contour where drainage flows away from it (peak) or into it (depression).
The Peaks and Depressions layer is similar to the current hachuring of closed contours, but with a few important differences:
- The peaks and depressions layer only enclose the base of a peak or depression, not all closed contours within each peak or depression. If you choose to hachure closed contours, then all closed contours are hachured.
- You can choose to display all local peaks and depressions, or just the highest peak or lowest depression area within the grid file.
- You can hachure and color peaks differently from depressions.
- You can mark the maxima or minima location within each peak or depression area with a symbol, and label it with the Z value.
- You can generate reports of the peak or depression areas including width, length, volume, area and orientation of each area.
To create the Peaks and Depressions layer:
- Click Home | New Map | Specialty | Peaks and Depressions
- In the Open Grids dialog, choose you grid file and click Open. The Peaks and Depressions Layer is created.
- Click the Peaks and Depressions layer in the Contents window to select it.
- In the Properties window, the General tab, Peaks tab and Depressions tab control the properties for the map layer.
- Click the General tab:
- Click the Peaks tab.
- Show peaks: Check/uncheck to show/hide peaks
- Line properties: Set the line properties for the Peaks polygons
- Fill properties: Set the fill properties for the Peaks polygons
- Maximum: Choose to put a marker symbol and/or label at the maximum point in each peak polygon (the label shows the Z value), set the marker symbol and label formatting properties
- Hachures: Choose to show hachures on the line and set hachure line direction & properties. You can set it to show only the areas (no symbol marker or label), or just show the symbol marker/label with no polygon areas
- Click the Depressions tab.
- Show depressions: Check/uncheck to show/hide Depressions
- Line properties: Set the line properties for the Depressions polygons
- Fill properties: Set the fill properties for the Depressions polygons
- Minimum: Choose to put a marker symbol and/or label at the maximum point in each depression polygon (the label shows the Z value), set the marker symbol and label formatting properties
- Hachures: Choose to show hachures on the line and set hachure line direction & properties. You can set it to show only the areas (no symbol marker or label), or just show the symbol marker/label with no polygon areas
- For the Peaks and Depressions Report (General tab):
- Click Generate Report. An Options dialog allows you to adjust the Z scale factor (e.g. if your Z is in different units than XY):
- Click OK and a report is created with statistics for all peak and all depression polygons that are visible on the screen.
- The combined peak and combineddepression statistics are followed by sections for each individual peak and each depression polygon. It shows the grid file, followed by the 4 possible sections:
- Peaks. This is the general data for all Peak polygons. It shows the number of polygons and then the statistics for them all together:
- Depressions. This is the general data for all Depressions polygons. It shows the number of polygons and then the statistics for them all together:
- Individual Peaks. Shows the statistics for each individual Peak polygons.
- Individual Depressions. Shows the statistics for each individual Depressions polygons.
- Note that peaks have Height and depressions have Depth. This is the height of the depression or peak, the difference in Z values of the outer edge of the polygon to the minima or maxima point.
Updated October 27, 2021
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