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+--- Thread: Slope Angle Shading (/showthread.php?tid=26016)
Slope Angle Shading - MojaveGeek - 2022-02-12
I use caltopo for my topo work, and in recent years I have become quite fond of its "slope angle shading" feature. Basically, it puts a color overlay on the topo to show you how steep the slopes are. I believe Gaia GPS has this also. My understanding is that this is based on much higher resolution data than simply measuring the distance between the contour lines on the topo map. it is certainly a way to choose the safest route and an important tool for off trail travel.
RE: Slope Angle Shading - DAW89446 - 2022-02-12
I use National Geographic TOPO! software on my computer, with mapsets for California, Nevada and Utah. It is no longer produced.
From what I deduce from your post, I believe the same can be achieved in TOPO!. You can view the raw topographic map as seen on the paper map, turn on shading that gives you more of a sense of contour and slope, turn on roads and street overlays, and you can turn on a 3D view of the map for a similar sensation that GE gives; though you are looking at the map in 3D, not imagery of the location as does GE.
In the past I never took advantage of online map services because I had no source of internet except by cell phone. Now lines have been run in my neighborhood and I now have full time high speed interent. But I still like my old TOPO! software, running on my ancient (in computer speak) 2007 Toshiba laptop running Windows Vista. But since I got high speed internet in December, I found GE, loaded the app on my iPad and found a new addiction.
RE: Slope Angle Shading - Daymoth - 2022-02-13
We use the caltopo slope angle specially in winter to see avalanche risk areas.
In summer its useful but less so since the terrain can be super solid and steep or look flat and be a jumble of boulders.
RE: Slope Angle Shading - MojaveGeek - 2022-02-13
(2022-02-12, 11:00 PM)DAW89446 Wrote: I use National Geographic TOPO! software on my computer, with mapsets for California, Nevada and Utah. It is no longer produced.
From what I deduce from your post, I believe the same can be achieved in TOPO!. You can view the raw topographic map as seen on the paper map, turn on shading that gives you more of a sense of contour and slope, turn on roads and street overlays, and you can turn on a 3D view of the map for a similar sensation that GE gives; though you are looking at the map in 3D, not imagery of the location as does GE.
No, this is something different. What you refer to is called "shaded relief" and is a good visualization tool. I don't know what data drives it. Slope angle shading is derived from something called Digital Elevation Models and is much more precise. It shows slopes as color coded and can often pick out a cliff band that is otherwise just noise with respect to the spacing of the topo lines.
Because you can move around in GE, that certainly does help to bring out relief, so I often refer to it as well. For example, I've just verified an actual section of the Skidoo pipeline - multiple sections, not the single section I found years ago next to an old road - but it's on a very steep slope and I probably cannot access it. I know how steep the slope is from the shading.
The default in GE is I think 2x vertical exaggeration. This makes things sometimes look hairier than they are. Just last night I was looking at my photos of the ridge where that pipeline section can be found, and the ridge looks more intense in GE than I read it to be in my photos. Anyway, I navigate by topos, and that's what I carry on my GPS and GPS app on my phone.
But all these are useful research tools for sure.
(2022-02-13, 12:28 AM)Daymoth Wrote: We use the caltopo slope angle specially in winter to see avalanche risk areas.
In summer its useful but less so since the terrain can be super solid and steep or look flat and be a jumble of boulders.
Yes, I was reading about such use just the other day. Yes there is no guarantee that a yellow or uncolored slope will be a piece of cake, but looking at satellite images can often give hints, at least where there is no vegetation, of what the ground looks like as well, so I often use in combination.
RE: Slope Angle Shading - Daymoth - 2022-02-13
Something we have also found is in narrow areas like ridges it can show white instead of the angle color. So if you dont check the topo lines you might think its a fairly flat ridge when its actually 40°.
RE: Slope Angle Shading - MojaveGeek - 2022-02-13
(2022-02-13, 08:29 PM)Daymoth Wrote: Something we have also found is in narrow areas like ridges it can show white instead of the angle color. So if you dont check the topo lines you might think its a fairly flat ridge when its actually 40°.
Good to know, thanks!
RE: Slope Angle Shading - DAW89446 - 2022-02-14
(2022-02-13, 04:11 PM)MojaveGeek Wrote: For example, I've just verified an actual section of the Skidoo pipeline - multiple sections, not the single section I found years ago next to an old road - but it's on a very steep slope and I probably cannot access it.
The pipe itself was reclaimed, but there are some single sections still left behind.