rankin lidar presentation

LiDAR Applications in

Surveying and Engineering

2013 NC GIS Conference

Raleigh, NC

Frank A. “Alex” Rankin, III PE, PLS

What is LiDAR?

• Light Detection and Ranging

• Analogous to RADAR, but using a different part

of the electromagnetic spectrum

• RADAR uses radio waves or microwaves

What is LiDAR?

• LiDAR uses light at or near the visible spectrum

(Visible spectrum occupies 390 nm - 700 nm)

• Aerial mapping LiDAR generally uses 1064 nm

Yttrium-Aluminum-Garnet lasers

What is LiDAR?

• LiDAR uses the laser to illuminate a target and

then analyzes the reflection

• The narrow laser beam makes it possible to map

objects with a high degree of resolution

What is LiDAR?

• The basic technology has been around

since the 1970s, but ---

• Because of size, cost and complexity had

limited (government) application, but ---

• Recent dramatic advances in laser and

detection technology, computational

speed, and memory storage have made

commercial applications possible

What is LiDAR?

• Smaller, faster, smarter LiDAR makes

possible direct measurement of complex

and hard to access structures

What is LiDAR

• Depending on the wavelength laser used, LiDAR can develop 3D point clouds of a wide range of objects, such as – rocks, non-metallic objects, rain, chemical compounds, aerosols, clouds, and even single molecules

What is LiDAR

• For Surveying and Civil Engineering the

most important applications are aerial

scanning and terrestrial scanning

What is LiDAR

• Terrestrial Scanning creates 3D models of

complex objects: piping networks,

roadways, archeological sites, buildings,

bridges, etc.

What is LiDAR

• One of the advantages of Terrestrial Lidar

is that objects can be measured remotely

making operations such as measuring

roadways under traffic much safer.

What is LiDAR

• Aerial Scanning has many uses - measuring agricultural productivity, distinguishing faint archeological remains, measuring tree canopy heights, determining forest biomass values, advancing the science of geomorphology, measuring volcano uplift and glacier decline, measuring snow pack, and providing data for topographic maps - to name a few…

Topographic Mapping

• In the past decade,

because of the

advantages of LiDAR,

it has largely

displaced

Photogrammetry as

the process for

development of large

scale topographic

maps

Topographic Mapping

(LiDAR Advantages)

• LiDAR sensors can

be operated in any

weather – (not so with

cameras- the clouds

get in the way)

• LiDAR sensors are

not affected by low

sun angles - which

would prevent useful

photos

Topographic Mapping

(LiDAR Advantages)

• IN FACT – LiDAR can

actually operate at

night!

• More hours of useful

flying per day means

LiDAR offers greater

efficiency, faster

results, and can cover

more ground than

photogrammetry

Topographic Mapping

(LiDAR Advantages)

• Rural and remote

areas are easier and

quicker to survey with

LiDAR because each

point has geo-

referenced location

and elevation – no

orthorectification of

image – no network of

photo panels required

Topographic Mapping

(LiDAR Advantages)

• Photogrammetry needs to be able to see the ground to create contours

• LiDAR returns come from every object illuminated – the lowest being the ground – wherever the sunlight hits LiDAR will return XYZ

Topographic Mapping

(LiDAR Advantages)

• LiDAR creates a 3D model directly from the returns

• Photogrammetry requires the incremental comparison of

a pair of stereoscopic photographs – indirect and much

more labor intensive

Topographic Mapping

(LiDAR Advantages)

• Photogrammetry requires contrast to see ground surfaces – desert, wetlands, beaches, coasts are difficult or impossible

• LiDAR results come directly from the returned signal – contrast not required

Public LiDAR Resources

• Public sources of existing LiDAR are

valuable resources for engineering and

surveying firms – some addresses are:

• http://www.ncfloodmaps.com/

• https://connect.ncdot.gov/resources/gis/Pa

ges/Cont-Elev_v2.aspx

• http://www.nconemap.com/

http://www.ncfloodmaps.com/

https://connect.ncdot.gov/resources/gis/Pages/Cont-Elev_v2.aspx




http://www.nconemap.com/


• These public sources are excellent for

large scale planning processes…

However……!


• North Carolina

Board of

Examiners for

Engineers and

Surveyors,

says….

….in its Spring 2012

newsletter…


“As to the use

of…floodplain

mapping LiDAR

elevation data should

not be used for final

design…” or it

“…could lead to

disciplinary

action…”


• But properly used these public sources provide

the base information for all types of planning

processes, such as – developing project specific

hydrology models for large areas…


• …or for developing

land use plans for

large residential,

commercial,

industrial, or mixed

use areas….


• …..or for view sheds

for parks, trails, and

other large outdoor

recreational areas….


• ….evaluating the relationship to environmental

sites….


• …planning for greenways and other recreational

amenities….


• …planning industrial sites….


• …industrial site selection by “site selection

consultants” (hired guns)….


• …and beyond initial planning the public sources

can be used for large scale schematic grading

exercises…

LiDAR in Civil/Surveying Firm

• Terrestrial LiDAR (Scanning) can rapidly map complex sites in much more detail than is possible with conventional means – this makes a better base sheet for design….


• …and even if not complex, it covers areas that

are large (but too small to fly) quickly….

LiDAR in Civil/Surveying Firm • Imagine a building – filled with piping….

LiDAR in Civil/Surveying Firm • …imagine crawling around that piping trying to

locate it by direct measurement…


• …and

the cost

(and

time)

savings

become

obvious.


• For larger

areas, site

specific aerial

LiDAR provides

base sheets for

all types of

project specific

civil engineering

design…such

as…


• …Master

Planning…


…Grading...


…Utilities...


…Drainage Analysis….


…Erosion Control and Stormwater Treatment…


…Roadway

Design…


…and much, much, more.

The End!

rankin lidar presentation

Technology

public lidar

public sources

civilsurveying

lidar sensors

lidar advantages

advantages

lidar

objects