Surveying, Surveyors

and

Geographic Information Geographic Information

Systems

Curt CrowNOAA’s National Geodetic SurveySeptember 22, 2009URISA New England, Bedford, NH

Surveying

The technique and science of accurately

determining the location of points on or near

the surface of the earth and the distances the surface of the earth and the distances

and angles between them.

Surveying by Francis H. Moffitt

Surveying

To accomplish their objective, surveyors use elements of:

geometry,

engineering, engineering,

trigonometry,

mathematics,

physics,

and law

geometry: from Greek geōmetriā, to measure land : geō-, geo- + metron, measure

Land Surveying

The detailed study or inspection, as by gathering information through observations, measurements in the field, research of legal instruments, and data analysis in the support of planning, designing, and establishing of property boundaries. establishing of property boundaries.

It often involves the re-establishment of cadastral surveys and land boundaries based on documents of record and historical evidence, as well as certifying surveys of subdivision plats/maps, registered land surveys, judicial surveys, and space delineation.

from the American Congress of Surveying and Mapping

Land surveying includes associated

services such as:

mapping and related data accumulation

construction layout surveysconstruction layout surveys

precision measurements of length, angle,

elevation, area, and volume

horizontal and vertical control surveys

the analysis and utilization of land data

Surveying through History

Surveying has been an essential element in the development of the human environment since the beginning of recorded history (ca. 5000 years ago) and it is a requirement in the planning and ago) and it is a requirement in the planning and execution of nearly every form of construction.

Its most familiar modern uses are in the fields of transport, building and construction, communications, mapping, and the definition of legal boundaries for land ownership.

Egyptian Surveys – the Rope Stretchers

In ancient Egypt, when the Nile River overflowed its banks and washed out farm boundaries, boundaries were re-established by a rope stretcher, or surveyor, through the application of simple geometry. application of simple geometry.

Egyptian Surveys – the Pyramids

The nearly perfect squareness and north-south orientation of the Great Pyramid of Giza, built c. 2700 BC, affirm the Egyptians' command of surveying.

Stonehenge 2500 BC

Recent discoveries indicate

that the monument was set

out by prehistoric surveyors

using peg and rope

geometry

Roman and Arab Empires

The Romans, established land surveying as a profession

and they established the basic measurements under

which the Roman Empire was divided including a tax

register of conquered lands (300 AD).

The rise of the Caliphate led to extensive surveying The rise of the Caliphate led to extensive surveying

throughout the Arab Empire. Arabic surveyors invented a

variety of specialized instruments for surveying, including:

Instruments for accurate leveling: A wooden board with a plumb line and two hooks, an equilateral triangle with a plumb line and two hooks, and a reed level.

A rotating alhidade, used for accurate alignment

A surveying astrolabe, used for alignment and measuring angles

England and Europe

In England, The Domesday Book by William the Conqueror (1086) contained names of the land owners, area, land quality, and specific information of the area's content and habitants. But, it did not include maps showing exact locations

Continental Europe's Cadastre, created by Napoleon Bonaparte Continental Europe's Cadastre, created by Napoleon Bonaparte (1808)

contained numbers of the parcels of land (or just land), land usage, names and value of the land

100 million parcels of land surveyed and mapped at scales of: 1:2500 and 1:1250

The Cadastre spread quickly around Europe but faced problems in Mediterranean countries, Balkan, and Eastern Europe due to cadastre upkeep costs and troubles

"A good cadastre will be my greatest achievement in my civil law“ NB

The Survey of the Coast

On February 10, 1807, President Thomas Jefferson founded the Survey of the Coast to provide nautical charts to the maritime community for safe passage into American community for safe passage into American ports and along our extensive coastline.

Later known as the Coast and Geodetic Survey and now known as NOAA’s National Geodetic Survey

Three Surveyors and some other guy

The Last Spike (1881) by Thomas Hill

Jupiter & #119 May 10, 1869 at Promontory Summit, Utah

A Surveyor's Five Main Areas of Work

Research, analysis, and decision making

Field work - Data acquisition

Computing - Data processingComputing - Data processing

Mapping - Data representation

Stake-out - Positioning points on the ground

The Two Major Methods of Surveying

Geodetic Surveying

Takes into account the shape of the earth.

Generally high in accuracy and covers Generally high in accuracy and covers

large areas

Plane Surveying

Assumes that the measurements are made

on a flat plane. Generally covers smaller

areas

Types Of SurveysControl – establishes the position of arbitrary horizontal and vertical points for the support of subsequent surveys and precise mapping.

Topographic – determines the configuration of the surface of the earth and objects on that surface.

Cadastral – establishes the positions of boundary or property lines. (aka Property or Boundary Survey)

Construction – lays out the horizontal and vertical positions of objects of a designed project.

Hydrographic – determines the depth of water, configuration of the bottom and heights and times of tides in a body of water.

Many more types including Route Surveys, Forensic Surveys

What do a GIS and a Survey have in Common?

Both are information management systems which can:

Collect, store, and retrieve information based on it’s spatial location

Identify locations which meet specific criteria within a targeted area

Explore relationships among data sets

Spatially analyze the data within each area

Display and analysis of the selected area numerically and graphically

Building the Foundation

All of this data is georeferenced: linked to a

specific location on the surface of the Earth

through a system of coordinates

A GIS or a survey are not limited to objects A GIS or a survey are not limited to objects

and their position, both can incorporate

properties of these objects as additional data

within the project

Understanding the framework is critical, ie.

datums and coordinate systems

Coordinate Systems

Surveyors are knowledgeable about Mapping

Datums. They routinely deal with:

Current and historic datumsCurrent and historic datums

Geodetic and tidal datums

Maps and charts with No Datums

Surveyors have experience finding solutions

to spatial problems in the field

Accuracy

The surveyor and the GIS specialist have approached accuracy from opposite directions

Surveyors are skilled in measurement techniques

GIS specialists manage, analyze and display large GIS specialists manage, analyze and display large amounts of critical data from a wide variety of sources

High speed computers, sophisticated mapping software and GPS have brought them together

The massive amount of data collected with “mapping grade” and “sub-meter” GPS brought GIS from digital renderings to spatially correct drawings

Surveyors and GIS Specialists have a Problem

Surveyors are driven by the details

GIS Specialists see the big picture

For the most part, each understands the For the most part, each understands the

limitations of their data

Problems arise when the Surveyor or the GIS

Specialist or, more commonly, a third party

misunderstandsmisunderstands that data, or the map or the

coordinate values derived from a digital model

Technology Stops for No One

“mapping grade” and “sub-meter” GPS made GIS accurate – to a point, but technology rolled on like that train in Utah

New high-resolution, stable platform, precisely New high-resolution, stable platform, precisely controlled digital imagery has made 1-meter photos look like cave drawings. In less than ten years we have gone from 1-meter imagery to 3-inch imagery

We’ve rubber-sheeted very old data to match the new maps. Now we have to rubber-sheet the ‘good’ data to match the ‘really good’ imagery

New Relationships

The GIS and Survey communities need to work

together to utilize each others skills. Surveyors can

help “keep the data in sync”

“For example: a community obtains new “For example: a community obtains new

orthophotography that is more accurate than the

existing base data in their GIS. Surveyors have the

equipment, technology and expertise to perform

these spatial updates”

From an online interview with

Brent Jones, Survey Manager, ESRI

Where does Survey fit in the GIS World?

Surveyors can:

Assist in the establishment of the control and parcel base

Collect data of geographic features to improve the Collect data of geographic features to improve the accuracy of remotely sensed imagery like orthophotos

Develop the points, lines, and areas for import into the GIS

Use their measurement knowledge to write the Metadata

Assist in the planning, development, and maintenance of the GIS