Google Earth: Color code by slope?

[RAWR]

So with ski season rapidly approaching, I've been spending a lot of time staring at google earth scoping out new backcountry zones and mountaineering objectives. What I'm looking for is a script that would 'color code' the terrain by slope angle, with a legend showing slopes in degrees. This would make it super easy to determine what's skinnable, skiable, avvy-prone, etc. The newest version of GE is an improvement, since you can right click on a drawn track and view the elevation profile and angle at any point along the path (which unfortunately is in % grade, not slope angle).

I remember seeing some static images of ski resorts color-coded by angle, so somebody must know how to do this. If there isn't anything out there yet, I might try to take a crack at it. Also, if anybody here is good at writing code, I could throw a few six packs your way to help the development process

[stalefish3169]

This is pretty easy to do with a GIS. Files can be exported in .kml format and viewed in ge. Not sure if ge can do the calcs as a standalone. I can do it if you give me the area or coordinates you're interested in.

[altis]

Have you seen:

http://openpistemap.org/

[Dromond]

I have wanted this exact feature!

[deliberate]

just add->path
draw the path
right click on it
and select show elevation profile.

If you click and drag over the elevation profile the range states will reflect the selcted area _avg slope, max slope, elevation change, distance.

I see, after rereading your first post, you kindof figured this out.

[RAWR]

Right, I mentioned this feature in my first post, but the main problem is that GE reports slope as percent grade. So for each point you want the angle at, you need to take the arc-tangent of the percent grade (expressed as a decimal), which gets kind of annoying.

My girlfriend is an ArcGIS wiz, I'll see if she knows anything about doing something like this.

[Dromond]

Does anyone know an easy way to convert % grade to slope angle? (i.e. formula, online calculator, whatever)

[Yanos]

Angle = arctan ( slope% / 100)

http://en.wikipedia.org/wiki/Grade_(slope)

[nickwm21]

^^ nice... someone remembered that 11th grade trig.

[Modogaus]

So with ski season rapidly approaching, I've been spending a lot of time staring at google earth scoping out new backcountry zones and mountaineering objectives. What I'm looking for is a script that would 'color code' the terrain by slope angle, with a legend showing slopes in degrees. This would make it super easy to determine what's skinnable, skiable, avvy-prone, etc. The newest version of GE is an improvement, since you can right click on a drawn track and view the elevation profile and angle at any point along the path (which unfortunately is in % grade, not slope angle).

I remember seeing some static images of ski resorts color-coded by angle, so somebody must know how to do this. If there isn't anything out there yet, I might try to take a crack at it. Also, if anybody here is good at writing code, I could throw a few six packs your way to help the development process

Hi Rawr, I just read your question and came across this option that you can try - it worked for me to colour code run paths according to speed, altitude or slope in Google Earth:
1. Draw your path in google earth and then save it as kml file
2. open GPS visualizer http://www.gpsvisualizer.com
3. Click on Google Earth Kml (to the right under more options)
4. Upload your kml file and set the desired settings, e.g. colorize by altitude
5. Create kml file and upload to Google Earth
It took me an hour to play around with the settings until it was perfect (click the + sign to see advanced options) but it works great....
I hope this helps.

[Nasty]

Angle = arctan ( slope% / 100)

http://en.wikipedia.org/wiki/Grade_(slope)

Frigin Alaskans are soooo smart.

[TripleT]

Hi Rawr, I just read your question and came across this option that you can try - it worked for me to colour code run paths according to speed, altitude or slope in Google Earth:
1. Draw your path in google earth and then save it as kml file
2. open GPS visualizer http://www.gpsvisualizer.com
3. Click on Google Earth Kml (to the right under more options)
4. Upload your kml file and set the desired settings, e.g. colorize by altitude
5. Create kml file and upload to Google Earth
It took me an hour to play around with the settings until it was perfect (click the + sign to see advanced options) but it works great....
I hope this helps.

This is AWESOME, thanks!

[SlopeAngleMaps_Dude]

I've been wondering the same thing for years, so I finally got around to making GE overlays. Go to my website:
www.slopeanglemaps.com
You can order color coded slope angle overlays for any U.S./Alaska region you want
Let me know what you think.
Cheers,

[JeffreyJim]

Any updates on this? I'd like something to overlay color over an area - hone in on zones based off said color...

[::: :::]

jeffreyjim, have you tried www.hillmap.com ?
(not mine, but i've used it)

find your location
go to the overlay menu
choose "custom slope analysis"
pick a slope angle and a grid density

[20:59]

Slope layer creation is actually very simple - you can do them using freeware like gdal or qgis.
In my experience, finding suitable elevation data is far more difficult as using SRTM or ASTER elevation data (freely available) only gives you about 30 * 30 m (or larger) pixels. My point here is that you can't really use that coarse slope layers in trying to find good spots. For example, all but the widest couloirs will disappear with the data filtering and averaging.

Finding elevation data with better spatial resolution (smaller pixels, or ideally lidar point clouds) can be surprisingly hard and/or expensive, depending on area of interest. Many of the datasets are not freely available and their file sizes can be HUGE.

North American elevation data (in various spatial resolutions) is available for example here: http://ned.usgs.gov

edit: example added, text edited

[land]

check out caltopo

you can select a couple of different slope angle layers (gradient or fixed (discrete?) shading) and overlay it onto several different map layers. It ain't google earth, but it's not bad.