There are some conditions that LIDAR handles badly.  We discovered that the charcoal fabric used on many office chairs is a very good IR absorber.  The SICK LMS won&#x27;t see those things at point-blank range.<p>Some LIDAR units give you &quot;first and last&quot;, that is, the time to the first reflection and to the last one. For a solid surface, both values will be very similar. For snow, rain, and foliage, they&#x27;ll differ quite a bit.  This is used in aerial surveys, where &quot;first&quot; gives you the tops of trees and &quot;last&quot; gives you the ground.  It hasn&#x27;t usually been available for ground-based LIDAR units, but there&#x27;s no reason it couldn&#x27;t be.