3

I'd like to identify mountain-peaks from an SRTM TIFF (created/composed from the original HGT ones).

How I'd wish it would work: Check for each pixel whether it is the highest value within a given radius (and I'd like to play with this radius). I know... it will generate some noise, but I will deal with it by having a larger "moving-frame" (i.e. bigger radius) up to 1-2 km.

This entry: how-to-calculate-peaks-in-a-dem asks basically the same and especially the (second) comment below the question from user/whuber phrases the problem perfectly - but I'd need a description (somewhat step-by-step) how to execute it.

The first (and chosen) answer would have been a nice start, but executing r.param.scale only throws an error ("Datenquelle ungültig" - "data-source invalid"), even though the same layer/file perfectly works with other GRASS tools.

Edit "Solution"

Turns out r.param.scale works perfectly, but you need to work in a projected coordinate system. So simply reprojecting to such a projected coordinate system solved my troubles.

within the r.param.scale one has to choose for the 'Morphometric parameter' and this will categorize all pixels from 1 to 6, being 1 = planes, 2 = pits, 3 = channels, 4 = passes, 5 = ridges, 6 = peaks.

As expected the results vary vastly depending on the chosen parameters.

/Edit

I am aware of this entry too: how-to-extract-mountain-peak-points-from-a-given-digital-elevation-model But there is not much practical advice given.

It seems this is a somewhat popular question brought up sporadically by amateurs like myself...

Community
  • 1
Chrugel
  • 557
  • 1
  • 5
  • 11
  • Seems that your troubles are not related to finding a tool, but actually making the tool you have work. Furthermore, are you sure that you aren't actually getting a result when running and GRASS throws an error? I just tested, and while it gave me an error message, it also produced the expected result. – Mikkel Lydholm Rasmussen Nov 05 '15 at 10:34
  • Well, it is making the tool work OR finding a method which works... I am happy with either of them.

    After your suggestion I checked, whether or not there is an output: there isn't. But I also read the in-tool protocoll, and there is an other error: "Lat/Long Location wird nicht unterstützt" (= "Lat/Long Location not supported"). But I don't know whether this is about the tool (r.param.scale) or about my SRTM TIFF.

     – Chrugel Nov 05 '15 at 11:03
  • This is a wild guess, but try to reproject your SRTM tile to a projected coordinate system, such as UTM, and then supply the tool with that file. – Mikkel Lydholm Rasmussen Nov 05 '15 at 11:20
  • Oh man... yup that's all it takes. Thank you very much! – Chrugel Nov 05 '15 at 11:57
  • 1
    Would be good if you could edit your question to reflect the solution, so that people that find the question using google also get the "answer". – Mikkel Lydholm Rasmussen Nov 05 '15 at 12:07
  • 1
    Solutions should be posted as answers instead of within the question. This way, answers can be accepted to show more clearly that it solved the problem. Also I think @MikkelLydholmRasmussen should post it as an answer :) – Joseph Nov 05 '15 at 12:23
  • @Joseph, it just seems strange to answer a question with a text that is based solely on a wild guess leaping from a part of the comments. – Mikkel Lydholm Rasmussen Nov 05 '15 at 12:28

0 Answers0