Clarify Handling of Near-Vertical or Overhanging Surfaces

Introduction

Inclusion of classified point data at, near, or overhanging vertical spaces in the bare-earth DEM results in undesirable interpolation artifacts due to the potentially large vertical separation between points on these surfaces. Ignored Ground is appropriate since these points are ground, but should not be included in bare-earth DEM.

Current requirement:

None, this is a new requirement.

Proposed Addition:

In Classified Point Data, after "Classification, as defined in table 5, at a minimum" add:

•  Ignored Ground (class 20) classification will be used for vertical, near-vertical, or overhanging bare-earth surfaces where inclusion of these points in the bare-earth DEM will result in undesirable interpolation artifacts due to the potentially large vertical separation between points on these surfaces.