Measuring slope steepness using apps

[Bad Bob]

Have "Clinometer" on the phone and have never used it skiing. I do you it for work occasionally.
Why would you care what angle the slope is at a given spot? Do you change your tactics at 37* or something?
You look, I'm going to ski it.

 

[Seldomski]

Is there a way to analyze a kmz file for slope? I have ski tracks -- they can export the path as kmz file. What I don't know how to do: take the kmz file and see the slope of the terrain. I can load it into google earth, but there isn't a tool there (that I am aware of) for looking at slope along the path.

 

[jmeb]

Is there a way to analyze a kmz file for slope? I have ski tracks -- they can export the path as kmz file. What I don't know how to do: take the kmz file and see the slope of the terrain. I can load it into google earth, but there isn't a tool there (that I am aware of) for looking at slope along the path.

CalTopo is your answer.

 

[surfacehoar]

In google earth, right click the line or path, then click 'show elevation profile' and it will show you the elevation profile.

 

[Doug Briggs]

Have "Clinometer" on the phone and have never used it skiing. I do you it for work occasionally.
Why would you care what angle the slope is at a given spot? Do you change your tactics at 37* or something?
You look, I'm going to ski it.

Snow safety. Avalanches have a range of slope steepness that makes them more likely to occur. Too steep and the snow can't load up. Too shallow and the snow can't slide. Knowing when you are in or out of 'the zone' is good to know.

 

[Ron]

Snow safety. Avalanches have a range of slope steepness that makes them more likely to occur. Too steep and the snow can't load up. Too shallow and the snow can't slide. Knowing when you are in or out of 'the zone' is good to know.

Aint that the truth never forget that when hiking or skinning that avalanches can occur above you or nearby. It isn't just where you drop in. Awareness is key!

 

[Seldomski]

CalTopo is your answer.

View attachment 67486

Hmm, does this work for Europe or just US? Not really understanding how to get slope % or degrees to show up. For Europe, it's showing 0 degrees for the route...

 

[Ron]

In google earth, right click the line or path, then click 'show elevation profile' and it will show you the elevation profile.

all this is important but just because the slope may say 20*, there can be rollers or sections where it could peak at 30*, you need to be aware of those zones and avoid them unless you "know" the conditions are safe.

 

[Seldomski]

In google earth, right click the line or path, then click 'show elevation profile' and it will show you the elevation profile.

Thanks, this shows slope in % along the path when you scroll over it with the mouse.

 

[Ron]

any idea how accurate this is? +/- what percent??

 

[jmeb]

Hmm, does this work for Europe or just US? Not really understanding how to get slope % or degrees to show up. For Europe, it's showing 0 degrees for the route...

Ah yeah, the slope layers aren't generated for Europe. Not sure where you are, but this is pretty awesome for Switzerland: https://map.geo.admin.ch.

 

[mdf]

Is there a way to analyze a kmz file for slope? I have ski tracks -- they can export the path as kmz file. What I don't know how to do: take the kmz file and see the slope of the terrain. I can load it into google earth, but there isn't a tool there (that I am aware of) for looking at slope along the path.

I really like the site http://www.gpsvisualizer.com/
It understands lots and lots of input formats lots of different data overlays it can create on a background map (speed, slope, elapsed, etc). I used to carry a Garmin GPS skiing and windsurfing and make images of the day -- slope for skiing, speed for windsurfing. (It was just for fun, and I don't usually carry the GPS anymore. My phone battery won't support a whole day with its GPS turned on.).

 

[Seldomski]

@jmeb this was for some offpiste route in Austria (St. Anton). Google earth shows max % slope of 49% (~26 deg). Ski tracks said max was 45 degrees. I do believe there may have been short sections (like 40 vertical feet) of 45 degrees. Not sure what resolution ski tracks is checking at vs. Google earth.

 

[Bad Bob]

Snow safety. Avalanches have a range of slope steepness that makes them more likely to occur. Too steep and the snow can't load up. Too shallow and the snow can't slide. Knowing when you are in or out of 'the zone' is good to know.

I do pay attention and steepness is part of it. Are there sluffs in the area? What are the layers like? Are the ropes up at the usually suspicious locations? But if there is a depth hoar layer down there, a 30* slope will bury you just as easily as a 45* slope (not quite as likely but just as easily).
Have been involved with avi control using the normal stuff; traverse, hand charges, recoilless rifles. Didn't ever use, or remember seeing the snow rangers ever use, an incline measuring device first.
Use them if you want to, just can not see the benefit.

Caveat! I did use my phone once to measure a slope while skiing. Had a bet going on how steep a slope was, and they bought the beer in the end.

 

[Seldomski]

I guess the other question I have about ski tracks... is it calculating max slope based on the path you are skiing or does it do something fancier -- like fit a plane to the path traveled of the last few seconds and find the angle of this plane vs. a reference flat plane

edit: My guess is the app is just looking at the last few points, distance traveled, and altitude change over that distance.

 

[nunyabiz]

Have "Clinometer" on the phone and have never used it skiing. I do you it for work occasionally.
Why would you care what angle the slope is at a given spot? Do you change your tactics at 37* or something?
You look, I'm going to ski it.

The first 9 or 10 posts of this thread initially happened in a different thread, when the mods spun this into its own thread some of the context for how the discussion began was lost.

 

[jmeb]

any idea how accurate this is? +/- what percent??

There is a great discussion by the developer of CalTopo about the limitations of slope angle calculation from remotely sensed data. It's in a TGR thread about the avalanche that killed someone in an Avy Level 2 class this winter. The summary is that remotely sensed data doesn't typically get fine-grained enough to pick up micro features, and estimates could be off by 2-3 degrees. This, of course, can be critical in avalanche terrain.

 

[Ken_R]

I was going to make the reference to Rambo as well to keep things in perspective. Rambo is 55 degrees and is the steepest cut run in the US.

https://www.redbull.com/us-en/theredbulletin/americas-steepest-ski-run

When you look at it from below it looks like a wall. Here's a view from the top.

 

[Mike King]

Have "Clinometer" on the phone and have never used it skiing. I do you it for work occasionally.
Why would you care what angle the slope is at a given spot? Do you change your tactics at 37* or something?
You look, I'm going to ski it.

I do pay attention and steepness is part of it. Are there sluffs in the area? What are the layers like? Are the ropes up at the usually suspicious locations? But if there is a depth hoar layer down there, a 30* slope will bury you just as easily as a 45* slope (not quite as likely but just as easily).
Have been involved with avi control using the normal stuff; traverse, hand charges, recoilless rifles. Didn't ever use, or remember seeing the snow rangers ever use, an incline measuring device first.
Use them if you want to, just can not see the benefit.

Caveat! I did use my phone once to measure a slope while skiing. Had a bet going on how steep a slope was, and they bought the beer in the end.

I suspect you are not skiing backcountry. And a 45 degree slope is much less likely to slide than a 35 degree slope due to a human trigger -- the snow probably already naturally released.

Mike

 

[Ken_R]

There is a great discussion by the developer of CalTopo about the limitations of slope angle calculation from remotely sensed data. It's in a TGR thread about the avalanche that killed someone in an Avy Level 2 class this winter. The summary is that remotely sensed data doesn't typically get fine-grained enough to pick up micro features, and estimates could be off by 2-3 degrees. This, of course, can be critical in avalanche terrain.

^^^ This.

I usually leave about a 5º margin for error. On days with dangerous avy conditions like we have now I might even increase that margin.