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I'm a complete novice at GIS. My project is to find the highest peaks in each Antarctic territory, and compare the results with the international gazetteer to find which peaks are and aren't named.

I'm trying QGIS Desktop with Grass with the 200m resolution radar altitude DEM raster file. Locations are (x,y) from the south pole in metres.

ftp://sidads.colorado.edu/pub/DATASETS/nsidc0082_radarsat_dem_v02/200M/ARCINFO/demosu200_v2.tar.gz

The Gazetteer is https://data.aad.gov.au/aadc/gaz/scar/download.cfm and is available as CSV, GeoJSON (whatever that is) and KML formats. Locations are in latitude and longitude to the nearest minute of arc, which is not accurate enough.

Territories are given by longitude range in Wikipedia

I've succeeded in opening the DEM with QGIS. I could find peaks manually one at a time using colours and the "identify features" button.

But is there a better way?

whyzar
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mollwollfumble
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    First you need to define your question more completely. How would you define a peak? Is the top of a gentle rise a peak? What about a mountain with two sharp points and a narrow 100m valley in between - is that two peaks or one? – Simbamangu Jan 01 '17 at 14:53
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    Wikipedia has some notes about "topographic prominence" https://en.wikipedia.org/wiki/List_of_highest_mountains_on_Earth – Spacedman Jan 02 '17 at 22:16
  • I'm distinguishing between "mountains" and "peaks". One mountain may have many peaks. For the definition of "mountain", I stick to the usage in the international gazetteer, no problems there. For peaks, I don't want to miss any so use a topographic prominence of 20 metres, which means that many of the objects I find as a "peak" will actually be labeled as "ridge, bastion, nunatak, heights, bluff, etc." in the gazetteer as well as "peak" and "mountain". – mollwollfumble Jan 02 '17 at 22:55
  • On a different aspect of the same topic - how does QGIF "save as image" work? Is there an image format that doesn't lose any raster data - retains the full height range of 0 to 5022 metres and has one pixel for each of the 28680*24580 datapoints - and has a utility that can change it to csv? I have software that can manipulate csv to find peaks if the csv is (i,j) ordered. – mollwollfumble Jan 02 '17 at 23:08
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    200m seems rather large for this task, that could contain allot of height variance. – AnserGIS Jan 03 '17 at 08:17
  • Agree, and if you have any more accurate method then I'd very much like to know it. The topographic maps are based on aerial photography done way back in 1959. The various gazetteers differ by a full 280 metres for the height of Antarctica's highest mountain, and by much more for many other mountains and peaks, if they have a height at all. The height accuracy of Google Earth topography in Antarctica is abysmal, when compared to the 200 m data. – mollwollfumble Jan 04 '17 at 01:31
  • Even that 200 m seems overoptimistic. It's gridded on 200 m, but the actual position accuracy is more like +-500 m. I think that's due to interpolating onto the grid from data taken along satellite path lines. Nothing can be due to improve that accuracy other than wait for the launch and results from icesat-2, due for launch this year. – mollwollfumble Jan 04 '17 at 18:29
  • "Is there an image format that doesn't lose any raster data - retains the full height range of 0 to 5022 metres and has one pixel for each of the 28680*24580 datapoints - and has a utility that can change it to csv?". Yes, I can save as gtiff and/or translate to ASCII xyz format. xyz file crashed on first attempt - big file - so trying again. – mollwollfumble Jan 04 '17 at 18:31

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