I found many posts here but no one was the solution for my problem. I would like to: 1.) digitalize forest roads, 2.) extract slope values from an underlying DEM, 3.) divide the roads into segments, 4.)color the segments according to their slope (see picture below. for example blue = slope 0-5%, yellow = 5-10%, violet = 15-20%, orange = 10-15%)
I would like to segment the polyline with kind of "terrain-based segmentation" where a segment is made where slope changes from one slope category into another. I also would like to assign this segments automatically to a slope category.
I am aware that there are many tools to segment lines.
Extracting the underlying elevation values is also not a problem (with extract or point sampling tools) but how to assign these values to a line and color it according to these values?
This approach (How do I find the slope of road segments with point elevation data of the same linear path) is good, but not working for QGis unfortunately.