New from CalTopo - high resolution slope angle shading
If you’re new to CalTopo and want to learn the basics, start with this tutorial video.
Note: this type of slope shading is made with an elevation model that may not show all relevant features and potentially hazardous avalanche slopes. It can be a useful tool for macro level trip planning, but is not accurate enough to completely assess potential avalanche hazard across all types of terrain.
Slope angle shading is a very cool feature of CalTopo, the best backcountry mapping software. It’s handy for lots of different reasons, and we cover them in detail in this article.
Canyoneers or photographers, looking for seldom-seen waterfalls?
Backcountry skiers, looking for a low angle ascent and a slightly steeper downhill?
Winter travellers looking to (hopefully) avoid avalanche slopes?
Cross country hikers or mountaineers, looking for the path of least resistance?
Slope angle shading can help in all of these situations. Now, the digital mapping data that underlie the slope model is improved, and the resulting shading is much higher resolution.
Here’s a comparison of the old and new slope angle shading, with the Disappointment Cleaver route (red line) on Mount Rainier. The top image is the older style shading, the bottom image is the newer one, using the higher resolution LIDAR data.
Pretty cool to see how the route picks it’s way up through the path of least resistance. You can use this feature to plan a cross country travel route in CalTopo for a place you've never visited! (Of course, glaciers can change on a daily basis and you should never fully rely on a model like this, but it’s a great start.)
Caveat: This new data set does not cover all of the United States, and is sadly lacking in many parts of the western US, but hopefully that will be improved in the next few years as additional LIDAR data are collected. See the data coverage map below. (Sorry Wyoming, Montana, and Sierra Nevada.) Good news, you are highly unlikely to be caught by an avalanche in Louisiana. =^)
Below is a copy/paste from the CalTopo website, Dec 20 2019.
http://caltopo.com/about/2019/12/20/high-resolution-elevation-data/
“CalTopo first launched the slope angle shading layer 7 years ago, and since then it has become a mainstay tool for backcountry trip planning. Today we're updating the layer to incorporate high-resolution LIDAR data from the USGS's 3DEP program. Where available (see coverage map), this provides significantly higher resolution, even allowing you to identify trails from relief shading. As additional coverage becomes available we will add it to this layer.
While the LIDAR data is very high resolution, it should still not be relied on as a definitive source of truth. Beyond possible errors or accuracy issues with the dataset or our processing of it, the surface angle on top of a snowpack may not match the bare-ground angle underneath. Carefully assess and evaluate any terrain that you are traveling in, and confirm your observations instead of relying solely on maps.
This update is now live on the web! It will be released soon on iOS and Android. Offering online access for free, and offline downloads with a CalTopo subscription. The significant increase in resolution means the offline downloads are larger in size than previous elevation data. Be cautious downloading using mobile data and storing on your phone, storage may go quickly.
As with previous expansions of the slope angle shading layer to Canada and Alaska, the high resolution dataset is not available to third party apps that license CalTopo's pre-rendered layers like Gaia GPS and Backcountry Navigator. You can only access the layer via CalTopo's website and app; we encourage you to download the new app to use this layer in the field.”
