Slope
Slope analysis calculates the change rate in value for a cell to its neighbors; that is, the steepness or flatness on the surface. On the output layer, each cell has a slope value, the smaller value stands for the flatter terrain; the larger value stands for the steeper terrain.
In Output Measurement, SuperGIS Spatial Analyst 3 provides three different measurement, percentage, degree and radius.
1.
Percentage
The most common method, it calculates each cell and the neighboring cell with DTM and get the percentage of elevation difference and horizontal distance. The formula is: Slope =(elevation difference/horizontal distance*100%) Example: Slope of 3 % stands for that whenever the horizontal distance is offset by 100 meters, the vertical distance goes up(or goes down) by three meters. Slope of 15% stands for whenever the horizontal distance is offset by 100 meters, the vertical distance goes up(or goes down) by 15 meters and so on. |
2. Degree
Represents the slope by degree. The degree is obtained by inverse Trigonometric functions, the formula is: Slope angle= If slope angle( If slope angle( If slope angle( So the steeper slope has larger tan. |
, tan
.
.3. Radius
The perimeter of circle =2 The angle multiplies the circular ratio(3.1415926...) and divided by 180. So, the perimeter of circle is 2
|
Radian
With Slope analyst, we can get:
1.The dense level of contour(the denser contours represents the steeper slope).
2.The shape of the contour(convex slope: the contour is much denser at lower elevation, and gradually sparse to higher elevation; concave slope: the contour is much denser at higher elevation and gradually sparse to lower elevation. )
Description of Parameters
Item |
Description |
Data Type |
Input Surface |
The data to perform slope analysis. |
Raster layer |
Measurement |
Switch measurement type: •Degree •Radian •Percent |
Measurement options. |
Z Factor |
The default is 1; it means the unit of vertical and horizontal direction are the same. |
Integer/floating point |
Cell Size |
The cell size of the output raster. |
Integer/floating point |
Output Raster |
The filename and storage path of the output raster. |
Raster layer |
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