CalTopo first launched the slope angle shading layer 7 years ago. 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.