Smooth Isolines

A generated isoline map in traditional analogical methods produces isolines with visual smooth properties. When isolines are obtained in digital systems from regular rectangle grid or irregular triangle grid, it is observed sharp corners. A smooth isoline method creates curve format to that data.

Catmull-Rom Spline was selected to smooth isolines due to its control point interpolation properties and calculation simplicity.

Isolines before smoothing:

Isolines after smoothing:

It is accessible through:

PROCESSING → DTM PROCESSING → ISOLINES SMOOTH...

1. Select Input Layer:

Use combobox or to select the layer containing the isolines that will be smoothed .

2. Target Scale: enter the scale value and click on the OK button beside the field.

3. Simplification Factor: this value will be used to do an input line filtering. Enter the wanted value in meters.

4. Maximum Distance: this value will define distance among simplified line points. Enter the value in meters.

5. Simplify output: click on this box if after lines being smoothed they will pass through Douglas_Peuckher simplification method using tolerance for simplification.

6. Set Output SRS

to select output layer SRS.

7. Inform the Output Repository by clicking on:

7.1.

to select the output directory and also inform the new layer name to store the result, or
7.2.

to select the Data Source and Inform the new Layer Name to store the aggregation result.

8. Click OK to perform the operation or Cancel to close the interface.