Cadalyst
— Cad Information - Hugh AutoLisp library
Professional
Surveyor — addresses the processes and tools of position and
measurement as well as the role of the surveyor
Earth
Observation Magazine
— EOM provides up-to-date coverage of developments with satellite
imagery, digital aerial photography, digital topographic datasets and
more!
GIS
Monitor (weekly)
— GIS Monitor takes a fresh look at GIS software, data, GPS,
location-based services, wireless and other industries and technologies
that touch the location technology arena
Federal
Base Network Surveys — The Federal Base Network provides
spatial reference control that has some of the most precise accuracies
available today.
Laser
Land Surveying Apparatus With Digital Display
— A land-surveying apparatus for use with a laser beam source to obtain
grade and range distances has a grade pole with a laser beam detection
unit slidably mounted thereon
Pole
Tilt Sensor for Surveyor Range Pole
— A surveyor range pole, for example, equipped with a GPS receiver and
antenna mounted at the top end, a battery mounted at the bottom end to
better balance the pole, a tilt sensor and a direction sensor
Computer
Assisted Video Surveying and Method Thereof
— One embodiment of the invention is a method of using a computer to
assist a land based video survey. Initially, a video recording of a
control location and a survey area is produced.
High
Speed Well Surveying and Land Navigation
— A land vehicle navigation apparatus incorporates an inertial angular
rate sensor on the vehicle and having a sensitive axis, and an inertial
acceleration or tilt sensor
Dymanic or Kinematic GPS
is becoming the default method of navigation for small craft as the
complex computations previously necessary are all performed on-board
the receiver. They work independently of the weather, 24 hours per day
( but not under trees or water), perform spheroidal calculations and
automatically convert between coordinate datums.
Static GPS
The
highest level of accuracy obtainable with GPS requires use
of two units, one as a base station and the other visiting the points
of interest. It is then possible to compute the vector between these
two units to a much higher degree of accuracy than we can compute
absolute latitude and longitude. Practically all the systematic errors
that can occur in GPS positioning can be eliminated if we measure to a
set of satellites simultaneously from two receivers, a process known as
differential positioning.
Differential Positioning
The typical configuration for
differential positioning is shown below, two units receiving signals
from the same constellation of satellites at the same time. The
relative position of the two units can be determined to a very high
accuracy, in many cases better than a centimetre. If one of these units
was located over a point for which we had ground control coordinates it
is then theoretically possible to obtain highly accurate coordinates
for the other point. This is indeed the case, providing all the
computations are performed in the one coordinate system.
This technique can be also applied if one of the receivers is on a
moving platform, or is moved between points of interest while the base
station remains fixed and continues to observe to the same satellites.
This produces new procedures known as rapid-static
positioning, kinematic
positioning and pseudo-kinematic
positioning. In general the units store the observations to the
satellites and are downloaded to PC type computers at the end of the
project. The differential solution is then computed using the complete
set of data from all the receivers. The latest hardware systems can
transmit the corrections between the base station and the rover
allowing the solution to be determined on-the-fly so that positioning
accuracies of around 0.01m are available in real-time.
Glossary of surveying and mapping terms
Aerial photography
Photography of part of the earth's surface, but is not
rectified to account for differences in scale throughout the photograph.
Altitude
The vertical angle between the plane of the
horizon and the line to
the object which is observed. In photogrammetry, altitude applies to
elevation above a datum of points in space.
Aneroid barometer
An instrument used to obtain heights above sea level by
measuring
atmospheric pressure. Since atmospheric pressure varies with the height
above or below sea level, the height can be read directly from the
height scale on the barometer.
Archaeological record
The archaeological record exists as a
repository. Inside lie the
decaying material remains of ancient beings and civilisations. As
archaeologists approach their work, they encounter raw data from the
archaeological record that serves as the source of their evidence to
interpret.
ATS
The Automated Title System is the computerised legal
register of
freehold land, State tenure land and Reserve land in Queensland. The
system also automates elements of the document receiving, lodgement,
tracking and registration processes.
Australian Height Datum
The datum used to determine elevations in Australia. The
AHD is based on mean sea level being zero elevation.
Azimuth
The horizontal angle measured from the meridian planes (a
plane which contains the polar axis, being true north).
Baseline
A surveyed line usually several kilometres
long. It is established
with the utmost precision available at the time.
Surveys refer to the
baseline for coordination and correlation. The
baseline accumulates
distances throughout a triangulation network, extending to other
baselines, providing further integrated control.
Beam compass
A drafting instrument used for drawing circles with a long
radius.
The point and scribe are separate units, mounted to slide and clamp on
a long beam.
Bearing
An angle measured clockwise from a north line of 0° to a
given surveyed line.
Bench mark
A permanent object, natural or artificial, displaying a
marked point whose elevation above or below an adopted datum is known.
Blaze
A mark carved in a tree trunk at about breast height,
signifying close proximity of a survey line
Cadastral
A Latin term from 'cadastre' referring to a registry of
lands.
Cadastral surveying is the process of determining and defining land
ownership and boundaries.
Cadastral map
A map depicting land parcels and associated nomenclature.
Cartography
The art and science of the production of maps.
This includes
the construction of projections, design, compilation, drafting
and
reproduction.
Chart
Special purpose navigation maps chiefly used for nautical,
aeronautical and mapping of the cosmos.
CISP
The Computer Inventory of Survey Plans is a database that
provides
current and historical survey plan information. It includes images of
all survey plans registered in Queensland.
Clinometer
An instrument used to determine the angle of elevation or
depression. A De Lisle's Pendent Clinometer was used by surveyors and
engineers to set out slopes and gradients in the construction of paths,
tracks and roads.
Compass
The magnetic compass has a pivoting magnetised needle that
always
points to magnetic north (geological features may influence readings).
The compass circumference is divided into degrees from which a bearing
of a chosen direction from magnetic north can be determined. A compass
magnetic bearing must be converted to a grid bearing for plotting on a
map.
Contour interval
The difference in elevation between adjacent contours as
delineated on a map.
Contours
Lines joining points of equal height as shown on a
topographic map.
Contour lines that are relatively close together depict an area of
steep terrain on the earth's surface.
Crown land
Land belonging to the reigning sovereign.
Datum
A mathematical representation that best fits the shape of
the
earth. Accurate mapping and coordinate systems must be based on a
datum. A new datum known as the Geocentric
Datum of Australia (GDA) was
introduced in 2000 to bring Australia in line with the rest of the
world's coordinate systems. GDA is also totally compatible
with
satellite based navigation systems, for example Global
Positioning Systems (GPS).
The previous datum used in Australia was known as the Australian
Geodetic Datum (AGD). However, this was restricted
because it was
defined to best fit the shape of the earth in the Australian region
only. The change in datums had a major consequence to all
coordinates.
Both latitudes/longitudes and eastings/northings were shifted by
approximately 200 metres in a north-easterly direction.
DCDB
The Digital Cadastral Database is the spatial
representation
of every parcel of land in Queensland. This
is along with its legal Lot
on Plan description and relevant attributes. It provides the
map base
for systems dealing with land related information.
Description of country
As described in the 1916 'Rules and Directions for the
Guidance of
Surveyors': "Country, whether undulating, broken, or rugged; timber,
whether open, thick, heavy, or with undergrowth; scrubs, their
character and situation, should be specially noted in field-books, as
the rate of additional payment that may be allowed on such account is
based on the information supplied".
EDME
Electronic Distance Measuring Equipment. This instrument
measures distances using light or sound waves.
Elevation
The height above mean sea level.
ERTS
Earth Resources Technology Satellite. This was later
renamed Landsat.
GDA94
The geodetic coordinate of latitude and longitude generated
using GDA
as the datum as at 1 January 1994.
Geocentric datum
A datum which has its origin at the Earth's centre of mass.
This
datum can therefore be used anywhere on the planet and be compatible
with the same datum anywhere else on the planet.
Geodesy
The science and mathematical calculations of the shape and
size of the Earth.
Geographical coordinates
A point on a map given as latitude and longitude readings.
The values are given as degrees, minutes and seconds.
Geographic Information Systems
GIS is the spatial capture of themed data layers and the
storing,
analysing and displaying of the geographically referenced information.
A GIS also includes the procedures, software, hardware, operating
personnel and spatial data associated with the system.
Global Positioning System
GPS is a satellite based navigation system originally
developed by
the United State's Department of Defence. A GPS receiver calculates a
position by measuring distances to four or more satellites of a
possible 24. These orbit the Earth at all times.
Graticule
A network of crossing lines on a map representing parallels
of latitude and meridians of longitude as defined by the projection.
Grid
A group of parallel lines that run perpendicular to another
group of parallel lines to form a map coverage of squares.
Grid coordinates
A point on a map given as an easting and northing reading.
The values are given in metres.
Grid north
The direction of the vertical grid lines shown on a
topographic
map. The difference between grid north and true north is referred to as
grid convergence.
Gunter's chain
A distance measuring device composed of 100 metal links
fastened
together with rings. The length of the chain is 66 feet. It was
invented in about 1620 by English astronomer, Edmund Gunter.
Hunter-gatherer
A member of a society who gains their subsistence in the
wild on food obtained by hunting and foraging.
Hydrography
Features including rivers, streams, lakes, swamps and other
water related features.
Hypsometric tinting
The use of different colours to signify changing elevations
on a topographic map.
Latitude
The angular distance along a meridian measured from the
Equator, either north or south.LeClanche Cell
The cell consists of a glass vessel into which a zinc rod
and a
cylindrical pot of porous earthenware is placed. The earthenware pot
holds a carbon plate. A mixture of equal parts of carbon and
needle
binoxide of manganese is packed around this plate. To set the cell into
action, the glass vessel is nearly filled with a saturated solution of
sal-ammoniac. A reaction takes place and a voltage of 1.46 volts is
generated.
Lifeways
A term often used within the discipline of archaeology and
denotes a customary way of living, or a way of life among people.
Lithography
This is based on the principle that water
and grease don't mix.
After an image is drawn on limestone with a greasy medium, the
stone is
dampened and ink is applied with a roller. The greasy image
repels the
water and retains the ink. Paper is then pressed onto the
surface.
Lockspit
Trenches dug beside a peg or post along the survey lines
from the
corner of a subject parcel. An example clause taken from the 1916
'Rules and Regulations for the Guidance of Surveyors' states:
On each side of the split pegs, and distant about one foot, lockspits,
three feet in length and six inches in depth, are ... to be dug in the
direction of the surveyed line. On very stony lands, rows of stones
placed in the direction of the surveyed line may be substituted for
dug-out lockspits.
Log tables
A set of tables used to abridge arithmetical calculations,
by the
use of addition and subtraction rather than multiplication and division.
Longitude
The angular distance measured from a reference meridian,
Greenwich, either east or west.
Magnetic north
The direction from a point on the earth's surface to the
north
magnetic pole. The difference between magnetic north and true north is
referred to as magnetic declination.
Map
A representation of the earth's surface where
constituancies and related nomenclature are portrayed to a specific
format.
Map projection
A means of systematically representing the meridians and
parallels of the earth onto a plane surface.
Map scale
The relationship between a distance on a map and the
corresponding distance on the earth's surface.
Mark
An object, for example an imprinted metal disc, used to
designate a
survey point. It is usually associated with terms such as reference
mark, azimuth mark or bench mark.
Material culture
A term that refers to the physical objects created by a
culture.
This could include the buildings, tools and other artefacts created by
the members of a society.
Measuring scales
Measuring scales allow the user to represent a subject or
drawing
to a recognisable reduction or constant ratio of the actual or proposed
size. Many early scales were made of silver, ivory, bone or boxwood.
Mercator projection
A conformal cylindrical projection tangential to the
Equator. Rhumb lines on this projection are represented as straight
lines.
Meridian
A straight line connecting the North and South Poles and
traversing points of equal longitude.
Metes and bounds
The oldest known form of describing the perimeter of a
parcel of
land. The method of describing the boundary of a parcel of land in
which the bearing and length of each successive line is given. Lines
may also be described as following some apparent line, for example the
bank of a stream.
MGA94
The Universal Transverse Mercator coordinates of eastings,
northings, and zones generated from GDA94 are called Map Grid of
Australia 1994 coordinates.
Mosaic
A number of continuous aerial photographs overlapped and
joined
together by way of 'best fit' to form a single non-rectified image.
Orthophoto
Aerial photograph images transformed using an 'orthophoto
verification' process to remove distortions and capable of registering
perfectly with cadastral data.
Overlay
Information recorded on a transparent medium, superimposed
and registered to one or more other records.
Peg
Used to mark survey corners on smaller portions or acreage.
The
size of the peg was determined by the 'Rules and Directions for the
Guidance of Surveyors' editions. These referred to various land acts of
the time from the 1860s onwards.
Photogrammetry
The science of obtaining reliable measurements by
photography.
Photolithography
The process used in a semiconductor operation, which
transfers the
pattern of an image held on a photomask, onto a flat substrate
surface. It follows similar principles to conventional
lithography.
PLI
The Property Location Index is a database which provides a
link
between the parcel identifier (lot on plan) and its location address.
It is considered the point of truth for location addresses.
Rectification
The mathematical and calculated correction made to an
aerial photograph to show its true ground position at a consistent
scale.
Rhumb line
A straight line connecting two points on the earth's
surface which
cuts all meridians at the same angle. The line maintains a constant
bearing.
RIME
The Resource Information Management Environment provides
for the
storage, management and dissemination of extensible digital topographic
data held within the Department of Natural Resources and Water. It is a
seamless, multi-scale environment covering Queensland.
Run
A large area of land in which squatters could depasture
their stock
without a lot of fencing necessary. Employed shepherds looked after
various areas of the runs. Runs became consolidated pastoral holdings.
Many of the runs were about 25 sq miles in area and
later became
parishes.
Sahul
This is the name given to the continent when Australia and
New
Guinea were a single landmass during the Pleistocene era. During this
period, sea levels were approximately 150 metres lower than present
levels.
Sandy Blight
A layman's term for chronic infection of the eyes with the
trachoma
organism, possibly leading to blindness. It is believed early European
settlers brought the trachoma to Australia. Their poor hygiene evident
in the low standard housing conditions, along with the dirt,
heat and
flies, caused the disease to become widespread. As
living
conditions improved, Sandy Blight in Australia had
all but disappeared
by the 1930s.
SCDB
The Survey Control Database is a computerised record of the
State's
geodetic survey control data. Surveyors place and connect to these
survey control points. The geodetic network provides a spatial
reference framework for all surveys.
Selection
Runs were subdivided into selections for farming,
agriculture and
grazing homesteads. After a period of yearly rental payments,
the
selector could often obtain freehold ownership.
SMIS
SmartMap Information Services is an electronic application
that
accesses, integrates and delivers (through the SmartMap
interface) data
available from many land-related datasets.
These include ATS, DCDB, CISP, PLI, SCDB,
Place Names and Aerial Photography Databases.
Spatial information
Data that has a geographical reference to a location on the
earth's
surface. This includes latitude and longitude co-ordinates, street
address and lot number on plan.
SunPOZ
Developed within the Dept of Natural Resources and Water,
SunPOZ
uses Virtual Reference Station technology by bringing together
GPS
architecture, networked computers and mobile phone communications to
output centimetre-accurate positions in real time.
Survey post
Posts used on corners of large rural size blocks of land or
town
section corners. They were sharpened to a point, buried in the ground
and exposed approximately 3'6" out of the ground.
Theodolite
Instrument used by a surveyor for measuring horizontal and
vertical angles.
Tindale, Norman
A well known Australian anthropologist born in 1900.
He was the
curator of anthropology at the South Australian Museum for over 30
years. He is remembered for his work with the Australian Aborigines
where he undertook the task of mapping Aboriginal Australia into
language and territory groups along with the recording of numerous
Aboriginal genealogies.
Topographic map
A detailed representation of cultural, hydrographic relief
and
vegetation features. These are depicted on a map on a
designated
projection and at a designated scale.
Transverse Mercator Projection
A projection similar to the Mercator
projection, but has the cylinder tangent at a particular
meridian rather than at the equator.
Trigonometrical survey
A concise method of surveying in which the stations are
points on
the ground located at vertices of a chain or network of triangles. The
angles of the triangles are measured instrumentally and the sides are
derived by computation from selected sides termed as baselines.
True north
The direction to the Earth's geographic North Pole.
The last glaciation of the ice age. An ice age is known as
a period
of low temperatures in the earth's climate causing an expansion of the
earth's polar ice sheets and mountain glaciers. There have been
approximately four distinct ice ages during the earth's history.
Education
in Surveying: Why Go to College?
In the formal surveying area, it is important to have core mathematical
skills such as algebra, geometry, trigonometry, and calculus.
This article appeared in the November 2004 issue of Professional
Surveyor.
Surveying
Units and Terms — list of units of measure, surveying terms,
surveyors' slang and abbreviations
CIA
World Factbook
— provides national-level information on countries, territories, and
dependencies, but not subnational administrative units within a country.
Acre - The (English) acre is a unit of
area equal to 43,560 square feet,
or 10 square chains, or
160 square poles. It derives from a plowing area that is 4 poles wide
and
a furlong (40 poles) long. A square mile is 640 acres. The Scottish
acre is 1.27 English acres.
The Irish acre is 1.6 English acres.
Arpent - Unit of length and area used in
France, Louisiana, and Canada. As a unit of length, approximately 191.8
feet (180 old French 'pied', or foot).
The (square) arpent is a unit of area, approximately .845 acres, or
36,802 square feet.
Chain - Unit of length usually
understood to be Gunter's chain, but possibly
variant by
locale. See also Rathbone's chain. The name comes
from the heavy metal chain of 100 links that was used by surveyors to
measure property bounds.
Colpa - Old Irish measure of land equal
to that which can support a horse or cow for a year. Approximately
an Irish acre of good land.
Compass - One toise.
Engineer's Chain - A 100 foot chain
containing 100 links of one foot
apiece.
Furlong - Unit of length equal to 40
poles (220 yards). Its name derives from
"furrow long", the length of a furrow that oxen can plow before they
are rested and turned. See Gunter's chain.
Ground - A unit of area equal to 2400
sq. ft., or 220 sq. meters, used in India.
Gunter's Chain - Unit of length equal to
66 feet, or 4 poles. Developed by
English polymath Edmund Gunter early in the 1600's, the standard
measuring chain
revolutionized surveying. Gunter's chain was 22 yards long, one tenth
of a furlong, a common unit of length in the old
days.
An area one chain wide by ten chains long was exactly an acre. In 1595
Queen Elizabeth I had the
mile redefined from the old Roman value of 5000 feet to 5280 feet in
order for it to be an
even number of furlongs. A mile is 80 chains.
Hectare - Metric unit of area equal to
10,000 square meters, or 2.471 acres,
or 107,639 square feet.
Hide - A very old English unit of area,
a hide was of variable size
depending on locale and the quality of the land. It was the amount of
land to support a family, and ranged from 60 to 180 acres. After the
Norman
conquest in 1066 it became standardized at around 120 acres.
Hundred - An adminstrative area larger
than a village and smaller than a county. In England it was 100 hides
in size, and the term was used for early settlements in Virginia,
Maryland, and Delaware.
Labor - The labor is a unit of area used
in Mexico and Texas. In Texas it equals 177.14 acres (or 1 million
square varas).
League (legua) - Unit of area used in
the southwest U.S., equal to 25 labors, or 4428 acres (Texas), or 4439
acres (California). Also,
a unit of length-- approximately three miles.
Link - Unit of length equal to 1/100
chain (7.92 inches).
Morgen - Unit of area equal to about
.6309 acres. It was
used in Germany, Holland and South Africa, and was derived from the
German
word Morgen ("morning"). It represented the amount of land that could
be plowed in a morning.
Out - An 'out' was ten chains. When
counting out long lines, the chain carriers would put a stake at the
end of a chain, move the chain and put a stake at
the end, and so on until they ran "out" of ten stakes.
Perch - See pole .
Point - A point of the compass. There
are four cardinal points (North, South, East, West),
and 28 others yielding 32 points of 11.25 degrees each. A survey line's
direction
could be described as a compass point, as in "NNE" (north northeast).
To improve precision,
the points would be further subdivided into halves or quarters as
necessary, for example,
"NE by North, one quarter point North". In some areas, "and by" meant
one half point, as in
"NE and by North".
Pole - Unit of length and area. Also
known as a perch or rod. As a
unit of length, equal to 16.5 feet. A mile is 320 poles. As a unit of
area, equal to a square with sides one pole long. An acre is 160 square
poles. It was common to see an area referred to as "87 acres, 112
poles", meaning 87 and 112/160 acres.
Pueblo - A Spanish grant of less than
1000 acres.
Rancho - A Spanish grant of more than
1000 acres.
Rathbone's Chain - A measuring chain
two poles, or 33 feet, in length.
Rod - See pole
Rood - Unit of area usually equal to 1/4
acre.
Toise - Traditional French unit of
length equal to 6 old French 'pieds' or feet, or 6.4 English feet.
Vara - Unit of length (the "Spanish
yard") used in the U.S. southwest. The vara is used
throughout the Spanish speaking world and has values around 33 inches,
depending
on locale. The legal value in Texas was set to 33 1/3 inches early in
the 1900's.
Virgate - An old English unit of area,
equal to one quarter of a hide. The amount
of land needed to support a person.
Surveyors' Slang
Balls - Slang for numeric .00, as in
4-balls (4.00)
Beep - Verb. To use a magnetic detector
to look for iron pipe, etc.
Boot - To raise the levels rod some
number of inches so as to be
visible to the instrument man, e.g. "Boot 6!" means "raise it 6
inches."
Blue topping - In road or grading work
the surveyor sets stakes and
paints their tops blue to represent the required elevation. Graders
then work to just cover the
blue tops of the stakes.
Bug - To use a magnetic locator to
search for an iron pipe.
Bullseye - Zero degrees of inclination.
Burn - See shoot
Burn one - Measure from the one foot
mark on the tape rather than from
the end of the tape in order to increase the accuracy of the
measurement.
Cut line - To clear vegetation for a
line of sight between two
survey control points.
Double nickel - Slang for .55, as in
6-double nickel (6.55)
Dummy or dummy-end - The base or zero
end of a tape or chain, as in "hold
dummy at the face of the curb."
EDM - Electromagnetic Distance
Measurement device, the instrument used
by modern surveyors that replaces the use of measurement chains. It
determines distance by measuring the time it takes for laser light to
reflect off
a prism on top of a rod at the target location.
Ginney - A wooden dowel 6-9 inches in
length with a sharpened
end. Set in the ground to mark survey points.
Glass - The EDM
prism.
Gun - Originally, a transit, but
potentially any measurement
instrument in use, e.g. theodolite, EDM, or Total
Station.
Hours - Degrees
Hub and Tack - A 2" by 2" stake that is
set in the ground and that
contains a nail ("tack") that precisely marks the point being set.
Jigger - Transit (Australia and New
Zealand)
Legs - Tripod
Pogo - Prism pole
Punk - See railroad.
Railroad - Slang for eleven, as in
42-railroad (42.11)
Rodman - The person holding the rod with
the EDM prism. This
person is the modern version of a chain carrier or chain man.
Shoot - Measure distance with an EDM
Spike - Usually a 60 penny nail used to
mark survey points in
hard ground.
Stob - In the southeast U.S., a wooden
stake or post, but in modern surveying, a piece of rebar used to mark a
property boundary.
Tie - To locate something with the
transit or other measuring device.
Top - Slang for eleven. See railroad.
Trip - Slang for triple digits, as in
trip5 means 555, and 43trip7 means 43.777
Turn - The rodman is told to stay in
place while the gun or level
is moved to a new location.
Zero - Zero degrees, minutes, and
seconds. A perfect zero.
Surveyors' Abbreviations
B.R.L. - Building restriction line.
FD - Found
IPF - Iron pipe found
IRF - Iron rod found
L.O.D. - Limit of Disturbance. The area to
be cleared, graded, etc.
MAG - New concrete nails are magnetic nails
and are stamped with MAG on the head and are easier to find with metal
detectors.
NPP - Nail in power pole
NTCFP - Nail on top of corner fence post
NTFP - Nail on top of fence post
PI - Point of intersection
PK - Point Known, PK nail
PK nail - A concrete nail made by Parker
Kaelon, stamped PK, that marks a survey point. See also hub
and tack.
