Making the Most of Your 3DEP Data
Published On: September 06, 2017
The USGS 3DEP initiative addresses the need for high-quality topographic data of the entire United States, through the systematic collection of LIDAR. However, as more and more municipalities receive their 3DEP data, several questions are beginning to arise including--what happens next? ??Join GeoCue Group's LIDAR professionals for an educational session as we explore the 3DEP initiative and ways to gain the most from the data.
What is 3DEP?
- 3D Elevation Program
- USGS initiative for high quality elevation data collection
- Data will be acquired over an 8-year period
- Lidar over most areas; IfSAR over Alaska
- Based on the National Enhanced Elevation Assessment (2012)
- Point Cloud Data available for direct download as .las/ .laz files
- Derivative products also available for download include:
- 1 arc-second DEM
- 1 meter DEM
- 1/3 arc-second DEM
- 1/9 arc-second DEM
- 2 arc-second DEM (Alaska)
- 5 meter DEM (Alaska)
- Contours (1:24,000)
What is LIDAR?
- Light Detection and Ranging
- Remote sensing method using light pulses to measure distance to Earth
- Provides precise, 3D information regarding surface characteristics
- Two types of LIDAR
- Topographic- used to map land
- Bathymetric- Used to measure seafloors and riverbed elevations
- Newer techniques include "Geiger-Mode" and "Single-Photon" lidar.
LIDAR Collection Methods
- Ground-Based (Terrestrial)
- Moving Vehicle
- Unmanned Aerial Vehicle (UAV)
USGS Quality Levels
- QL0- Added for anticipated advancements in LIDAR
- QL1- Building footprints
- QL2- High resolution elevation models; Breakline extraction
- QL3- 2' Contours
What Can I Derive from My 3DEP LIDAR Data?
- Digital Elevation Models
- Digital Surface Models
- Hillshade Models
- 3D Features
- Building Footprints
- Vegetation Canopy Outlines
How Can Extracting 3D Features Help Me?
- Convert point cloud data to feature data such as vectors for building footprints or vegetation canopy outlines
- Building footprints can be used for projects such as city planning and utility management.
What are Breaklines?
- Vectors used to define and control surface behavior for smoothness and continuity.
- Can be 2D or 3D (but moving to 3D for all breaklines).
- 3D breaklines can be fixed elevation or can vary with the terrain.
- Required for many applications, for example USGS requires hydro breaklines
How Else May I Receive Value from My Data?
- Point Classification
- A common feature coding technique to add value to the dataset.
- Allows for custom application development
- Surface Modelling