tom_brennan wrote:So finally I'd get a better map. For this you can turn to the new DEMs from ELVIS, and the free QGIS application. Here's a much better map of the area around your Pass 4. Red is cliff, white is easier ground, other colours are in between. Looking at your Pass 4, I'd head down the eastern creek until it gets steep, then traverse out over the spur to the western creek, and then out to the west and down to the Colo.
tom_brennan wrote:In QGIS, use the Slope function in the Processing Toolbox on the DEM, then style it like this:
I've found that to give a pretty good representation of cliffs.
For identifying passes, you obviously have to interpret it with some knowledge of the general area. And it won't necessarily identify passes that use cave systems, ledges or narrow slots, as these features may not show up from the DEM.
There's some information on creating contours and stream extraction at http://maps.ozultimate.com/wiki/nsw_lidar , but I have some more automated processes that I'll probably add when I have some time.
tom_brennan wrote:In QGIS, use the Slope function in the Processing Toolbox on the DEM, then style it like this:
I've found that to give a pretty good representation of cliffs.
For identifying passes, you obviously have to interpret it with some knowledge of the general area. And it won't necessarily identify passes that use cave systems, ledges or narrow slots, as these features may not show up from the DEM.
There's some information on creating contours and stream extraction at http://maps.ozultimate.com/wiki/nsw_lidar , but I have some more automated processes that I'll probably add when I have some time.
ILUVSWTAS wrote:I fixed no.1 for you.
tom_brennan wrote:I have some more automated processes that I'll probably add when I have some time.
rcaffin wrote:Now try some of those tricks in the Wollemi NP.
mandragara wrote:OK follow-up: These maps work so well it's almost like cheating. I walked up\down ridges near the Colo 4 times yesterday, with three of the 4 being 'new' ones identified by this GIS software. Each one was a breeze compared to some of Bob Buck's passes. I'm astounded by how accurate they are, they even work for deciding if you should go left or right to find a way up a cliff-line. This was in the general area around\east of Mt D'Arcy.
mandragara wrote:Also why is there a cairn on that mountain *before* Mt D'Arcy and not on Mt D'Arcy itself. Bizzare.
tom_brennan wrote:
They'll work well in the lower Colo, with its broken clifflines and open topography. Other parts of the world can prove trickier - you have to do a bit of mental calibration for different areas. That said, adding the slope to the maps has been a major improvement. 5m contours are good, but can still hide all manner of sins!
tom_brennan wrote:
No idea. Because the views are better from Not-Mt-D'Arcy?
It's roughly on the parish boundary of Wheeny and Bowen, so could be a boundary marker or some kind of survey aid. It's pretty heavy rocks!
https://ozultimate.com/tom/bushwalking/ ... _13578.jpg
mandragara wrote:Noted! I mostly walk in the Greater Blue Mountains area though (BMs, Wollemi and Yengo) - I'll keep this in mind if I go to different parts of the country\world.
mandragara wrote:Tom I am convinced you have been everywhere xD Have you been to every named mountain on the topo map? Genuine question haha
wildwanderer wrote:Any chance you can add this wizardry to your maps Tom as an overlay?
tom_brennan wrote:Not a chance - it's 50GB of raw data just for Sydney and the Blue Mountains! That would cost $$$$ to serve, assuming I could work out how to process and store it en masse.
icefest wrote:tom_brennan wrote:Not a chance - it's 50GB of raw data just for Sydney and the Blue Mountains! That would cost $$$$ to serve, assuming I could work out how to process and store it en masse.
I have not even found an easy way to view it in qgis, other than only loading a 2x2km area of interest.
mandragara wrote:I'm able to merge the areas of interest into a virtual raster and then process that as a big chunk in QGIS, but there's a file limit so I can't process a ton. I can use a command to merge them all as a TIFF but the output is much larger than the .asc files that go into making it. A TIFF that covers all of the Greater Blue Mountains would be 11 terabytes or so. I'm investigating if there's a way of merging the raw .asc files.
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