Hello FME-rs
Has anyone had success generating Ridge Lines (a line formed along the highest points of a mountain ridge)?
It is the area of higher ground separating two adjacent streams or watersheds.
I am aware that FME can generate surface model with various components (TIN, triangles,tin edges, tin surface, contours etc) from elevation data.
My interest is only with Ridge Lines from the DEM or Surface Model.
Any ideas are welcome.
Thanks
SRG
Hi @srg,
My take on this would be to isolate and define what is the area of interest in the DEM (mountain chain for example) and test for the cells with the highest Z value.
Generate points from the selected DEM cells and connect them.
Untested! since we don't have mountains here in The Netherlands :)
hope this helps.
Sort of related... I worked on a "heap detector" workspace last year, which was meant to detect piles of materials on an otherwise flattish surface that was surveyed through lidar. I generated a TIN and then looked for triangles with a certain slope value that had an elevation that was very close to that of the outline of the area.
In your case you can attempt this too, but look for triangles with a very low slope value that are higher than the surrounding area. It'd be an approximation and you would need to make your triangles rather small. I'm also not sure how succesful it would be in detecting ridges that lead up a mountain.
Hi @srg,
My take on this would be to isolate and define what is the area of interest in the DEM (mountain chain for example) and test for the cells with the highest Z value.
Generate points from the selected DEM cells and connect them.
Untested! since we don't have mountains here in The Netherlands :)
hope this helps.
When you test for cells with highest value, then only few isolated cells will get listed.
I used the RasterBandExtractor to get the min and max elevation.
But depending on the terrain, the single maximum elevation value will match with only few more cells. This means we will not be able to get the ridge lines from this approach.
I also tried using a tolerance value for cell selection (something like elevation of cell >= (max elevn-5)). But this approach does not give the desired results because of isolated cells being selected away from the ridge line.
Still thinking about the best way to go about :-(
Sort of related... I worked on a "heap detector" workspace last year, which was meant to detect piles of materials on an otherwise flattish surface that was surveyed through lidar. I generated a TIN and then looked for triangles with a certain slope value that had an elevation that was very close to that of the outline of the area.
In your case you can attempt this too, but look for triangles with a very low slope value that are higher than the surrounding area. It'd be an approximation and you would need to make your triangles rather small. I'm also not sure how succesful it would be in detecting ridges that lead up a mountain.
the challenge with the slope approach is being able to arrive at the ideal value to get the ridge lines out.
The slope value is terrain dependent.
The logic should be something that works on getting a series of highest elevation values and then connecting them.
I am thinking of doing a extraction of highest elevation by rows or columns and then connecting these cells to see if I can get the ridge lines.