Coastal Services Center

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LIDAR

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Summary | Different Data Products | Applied Uses | Specifications | Data Ordering Details | Frequently Asked Questions | For More Information

To browse elevation data available for download or learn more about topographic mapping activities at the NOAA Coastal Services Center, please visit our Topographic Change Mapping home page.

Summary

LIDAR (Light Detection And Ranging) is an active sensor, similar to radar, that transmits laser pulses to a target and records the time it takes for the pulse to return to the sensor receiver. This technology is currently being used for high-resolution topographic mapping by mounting a LIDAR sensor, integrated with Global Positioning System (GPS) and inertial measurement unit (IMU) technology, to the bottom of aircraft and measuring the pulse return rate to determine surface elevations. A recent University of Georgia Lidar-101 movie provides an overview of lidar, the technology, its costs, derived products, and some common applications.

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Different Data Products

Point to the names below to view the different data products.

Digital Elevation Model Grid
Contours
Raw Point Data
Intensity Image

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Applied Uses

Examples of how LIDAR data are being used:

Updating State Flood Insurance Rate Maps Managers in North Carolina were unable to adequately plan for and manage the flooding brought by Hurricane Floyd because a large proportion of the state's Flood Insurance Rate Maps (FIRMs) were old and outdated. In response, North Carolina initiated a statewide floodplain mapping effort using LIDAR data as its source for accurate and detailed elevation data.

Establishing Beach Setback Lines State law requires that South Carolina's beach setback lines be revised every 10 years. In 1998, the state's coastal managers began using LIDAR data for this purpose.

Other Potential Uses:

LIDAR data products can be used to address a number of topographic issues:

• Shoreline and Beach Volume Changes
• Flood Risk Analysis
• Water-Flow Issues
• Habitat Mapping
• Subsidence Issues
• Riparian Studies
• Forestry Management
• Emergency Response
• Transportation Mapping
• Telecommunication Planning
• Urban Development

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Specifications

The table below outlines the major specifications for LIDAR mapping technology. Standard specifications were collected from a variety of frequently used LIDAR sensors. These specifications may not apply to all sensors.

Topographic LIDAR Specifications

Pulse Rate	≤ 40 KHz
Wavelength	1.045 - 1.065 µm (near infrared)
Altitude	300 - 2000 meters
Swath Width	Up to 0.70 x altitude (meters)
Z Accuracy (Vertical) RMSE	Approximately 15 centimeters*
X, Y Accuracy (Horizontal) RMSE	≤ 1 meter*
Resolution (point spacing)	≥ 0.75 meters
Laser Footprint on ground	≤ 0.50 meters

Temporal Resolution – Revisit rate is dependent upon flight scheduling. LIDAR can be flown at night, which can improve scheduling time.

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Data Ordering Details

Data Acquisition	There are a number of private companies, academic institutions, and government agencies that produce and provide LIDAR data. more info
Timing	There are a number of time constraints associated with LIDAR collection and delivery: • Flight schedules can be delayed due to weather and environmental factors. • Project areas may be large enough that multiple flights are needed. • Post processing of millions of raw data points can be time consuming. • Producing additional deliverables can delay the delivery schedule.
Cost	Cost can vary depending on size of project, horizontal postings (point density), and project location. Cost may also increase based on additional product requests (i.e., DEMs, DTMs, contours, etc.), specific accuracy requirements, or licensing restrictions. more info
Data Formats/Software Needed	There are no standard file formats for LIDAR data, but raw point data can be delivered as georeferenced data in ASCII format. The ASCII format can easily be converted to binary raster data and then to other formats (e.g., GRID, TIFF, IMG, etc.). Converting ASCII to a binary raster file reduces the file size and creates a more compatible file format for software packages. In an effort to standardize a file format, the LIDAR industry is proposing a binary raw point format. more info
Projections	LIDAR data can be delivered in many different projections and datums. The national standard for vertical datum is the North American Vertical Datum (NAVD 88), and the national standard for horizontal datum is the North American Datum of 1983 (NAD 83).
Licensing	Licensing restrictions vary for each LIDAR service provider. Many providers do not have restrictions on their data products, but some companies do require licensing.

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Frequently Asked Questions

Data Acquisition

Who produces the data?
There are a number of private companies, academic institutions, and government agencies that produce and provide LIDAR data. A list of data producers can be found at the Airborne Laser Mapping Web site.

Can I download or request LIDAR data on-line?
There are a few government agencies and academic institutions that will allow you to freely download or request LIDAR data.

• North Carolina Flood Mapping Program: LIDAR DEM Data and Bare Earth Data
• The Louisiana Statewide GIS Atlas: LIDAR DEM Data
• The NOAA Coastal Services Center: LIDAR Point Data and DEMs

Cost

How much does it cost?
The average cost range for LIDAR x, y, z point data is approximately $1,000 to $2,000 per square mile for 2 to 3-meter postings. This cost includes flight, LIDAR collection, post processing, and delivery. Cost can vary depending on size of project, horizontal postings (point density), and project location. Cost does not include additional products (i.e., DEMs, DTMs, contours, etc.), specific accuracy requirements, or licensing restrictions.

Data Formats/Software Needed

What types of software are required?
Raw x, y, z points can be efficiently imported and spatially rendered by certain types of software. The following are examples of commercially available software:

• IDL by Research Systems Inc.
• MATLAB by MathWorks
• TerraScan by Terrasolid is software that runs on top of Bentley's Microstation.

If raw points are converted to raster format, most GIS/Image Processing software can be used to perform topographic analysis. The following are examples of commercially available software:

• ESRI products
  • ArcView 3.x and 8.0 with Spatial Analyst extension
  • ARC/INFO GRID
• Surfer 8.0 by Golden Software Inc.
• MapInfo Vertical Mapper module by MapInfo Corp.
• ERDAS Imagine 8.5 by Leica Geosystems
• ER Mapper by Earth Resource Mapping Inc.

A more complete list of software tools can be found at Airborne Laser Mapping.

Is freeware available for using these data?
The NOAA Coastal Services Center provides a free software tool for using LIDAR data:
LIDAR Data Handler Extension: An ArcView 3.x extension created to give users specific tools to manipulate the Center's LIDAR data in ESRI GRID format.

What are some of the LIDAR data products available?

What are the approximate file sizes for raw x, y, z point data (ASCII format)?
LIDAR data can contain millions of x, y, z points for a given area. This can translate into large file sizes, depending on the collection area and data resolution.

Approximate file sizes for raw x, y, z point data in ASCII format:

Area	1-meter Resolution	2-meter Resolution	3-meter Resolution	4-meter Resolution	5-meter Resolution
1 square mile	77 MB	19 MB	8.5 MB	5 MB	3 MB
1 square kilometer	30 MB	7.5 MB	3 MB	2 MB	1 MB

Approximate file sizes for raw x, y, z point data in 32-bit binary raster format:

Area	1-meter Resolution	2-meter Resolution	3-meter Resolution	4-meter Resolution	5-meter Resolution
1 square mile	10 MB	2.5 MB	1 MB	0.6 MB	0.5 MB
1 square kilometer	4 MB	1 MB	0.4 MB	0.25 MB	0.15 MB

The hardware used for LIDAR processing must support the file size and software memory requirements.

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General Questions

What technical expertise is needed to use/analyze the data?
Experience working with topographic data may be needed to analyze and process LIDAR data.

What are the limitations of LIDAR data?

• LIDAR has difficulty mapping earth surfaces with dense vegetation. Pulse returns can scatter and reflect within vegetation causing variation in elevations, thus limiting the penetration and return from "true" earth surfaces.
• Accuracies are limited by the inherent errors from the onboard GPS, and the inertial measurement unit (IMU). The GPS records the plane's positional x, y, z coordinates, while the IMU corrects errors in coordinate measurements caused by pitch and roll from the aircraft.
• Most LIDAR lasers use near-infrared (NIR) radiation. Certain materials and surfaces, such as water, asphalt, tar, clouds, and fog absorb NIR wavelengths causing null or poor returns.
• LIDAR can produce very large data file sizes.

How do clouds affect the data?
Topographic lidar can not be collected through clouds or dense haze/smoke; however, the data are collected at relatively low altitudes, often below cloud level, and can also be collected during the night when cloudy conditions are less pervasive.

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For more Information

• Airborne Laser Mapping Web Site
• NOAA Coastal Services Center Topographic Change Mapping Project
• NASA Observational Sciences Branch
• U.S. Geological Survey (USGS) Center for Coastal Geology

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