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.