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--- qgis_contours [2021/03/19 12:12] – bushwalking
+++ qgis_contours [2024/05/13 08:08] (current) – Contour screenshot bushwalking
@@ Line 5: / Line 5: @@
 There are various contour extraction algorithms in QGIS, for example:
   * GDAL : Raster Extraction : Contour (same as Raster -> Extraction -> Contour...)
+The two key fields are the //Input layer// (a DEM, ideally with sinks removed), and the //Interval between contour lines//. I typically use 10m or 5m for this.
+{{::qgis_gdal_contour.png?600|}}
 Below is an example of contours created without and with [[qgis_depressionless_dem|sink removal]]. The contours on the right have been derived from a DEM where the sinks (in yellow on the left) have been filled.
@@ Line 29: / Line 33: @@
 {{:contour_loops.png|}}
-Here is one approach, which involves adding a length attribute to each contour, and removing those that fall below a certain length. It may cause issues if you have short sections of contour near the edge of the map that you need.
+Here is one approach, which involves adding a length attribute to each contour, and removing those that fall below a certain length. It may cause issues if you have short sections of contour near the edge of the map that you need. However, that shouldn't be a problem in most scenarios.
   * Open Attribute Table (F6)