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Guide to Basic Surveying
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Contents
2. Introduction, Graphic recording
3. Drawing scales, Publication issues, Drawing materials, Drawing symbols
4. Field survey symbol sheet. Fig. 1
5. Building plan with explanatory captions scale1:100 . Figure 2
6. Methods of survey: Field sketch. Fig. 3.
7. Annotated Field sketch. Fig. 4
8. Methods of survey: Dimensioned sketch
9. A dimensioned sketch. Fig. 5
10. Methods of survey: Tape and offset survey (extended baseline survey) Fig. 6
11. Tape and offset survey in a single building. Fig. 7
12. Methods of survey: Plane table and alidade survey. Fig. 8
13. Plane table and alidade survey carried out to record detail. Fig. 9
14. Methods of survey: Elevations and Sections. Fig. 10
15. Plan and elevation Fig. 11, and section Fig. 12 through a black house
16. Plan of a Perthshire township, drawn with plane tables scale 1:250
17. Plan of a Benbecula farmstead, drawn with plane table and offset scale 1:200
18. An Aberdeenshire farmstead, drawn with plane table scale 1:500
19. A Dumfriesshire settlement, survey and AP transcription scale 1:2500
20. Examples of location maps scales 1:1000 and 1:2500
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Introduction
There is a growing interest in our built heritage, the
subject matter ranging rom prehistoric monuments and
historic townships to more modern military or industrial
sites.
Studying a subject can include carrying out
documentary research and looking at extant remains.
The record can include old documentation and maps,a written description, photography and sketches or
measured survey drawings.
This guide is intended to assist in the process o
graphically recording extant remains. It has been
created in the context o the Scotlands Rural Past
project where the range o survey equipment available
to the participants will be limited and describes
traditional survey methods using plane table, alidade
and tape measures. Most o the examples used in
this guide are o post-medieval remains but the same
survey techniques can be used to record all types o
buildings and sites.
Graphic recording
The purpose o graphic recording is to provide a set o
drawn illustrations (e.g Figures 13 -17) to provide a record
a site at a point in time that can be viewed and used or
research by other interested parties.
A graphic record o a building or structure normally
takes the orm o a combination o plan, elevation andsection drawings. Perspective or 3D orthographic
views can also be created as required.
t o graphic recording, oten undervalued,
is the process o surveying itsel.The surveyor is
required to spend time looking at and understanding
the site or building. Drawing, in either sketch or
accurate scale orm, is a subjective process requiring a
clear understanding o what is to be drawn. I a complex
eature is not understood on the ground it is unlikely
that the survey drawing will produce a clear depiction.
It is necessary to make inormed decisions on what thekey elements o a structure are and how to depict them
using lines or symbols. The amount o detail will vary
according to scale.
Understanding the process o generalisation, i.e. using
ewer lines to represent a structure at smaller scales, is
also crucial to the success o the depiction. The smaller
the scale, the more generalisation takes place but
overall shape and orm must not be lost.
A plan, (Figure 11a) in the case o a building, is a horizontal
slice, usuallly above window sill level,to show foor
layout, posi tion o doors, windows, replaces etc.
For an earthwork a plan is a view looking down on to the
eatures rom above.
An elevation, (Figure 11b) is a view looking on to an
upstanding structure or wall to show position and height
o eatures.
A section, (Figure 12) is a vertical slice through a building
or stru cture to show foor levels, ceiling heights andwall thicknesses. For an earthwork a section would show
a ground pro le and the height o banks, etc.
.
.
.
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Drawing scale
A clear understanding o what a survey is trying to
convey is essential in the selection o an appropriate
survey scale. Beore starting the survey time should be
spent walking over the site to determine its extents and
boundaries.
What are you trying to illustrate: the site location,position in the landscape, position relative to other
buildings, size and orm o the structure itsel or a
detailed part o a building?
Too small a scale can make it impossible to depict
important archaeological detail, too large a scale
ort, oten without any
useul gain in inormation. It is better to show the whole
c areas as
required to show more complex detail.
tting the drawing
onto the drawing board. I too large a scale is used,the resulting survey may need to be spread over more
than one sheet. This becomes unwieldy and may cause
problems i the drawings need to be re-sized or use in
a report.
The logical approach is to create a suite o illustrations
that may include:
Individual building or structure
1:50 - 1:100 is used to show the detailed character o
a single building or monument, e.g. a hut-circle, cairn,
replaces, drains,
agstones and stairs can be depicted accurately
without recourse to symbols.
Details or eatures
1:20, 1:10, 1:5 up to 1:1 or enlargements can be usedto illustrate particular eatures, such as carved stones,
les and excavation details, as required.
Publication
Survey drawings or derivatives are oten incorporated
into a publication or report. These reports are normally
A4 or smaller in size, so consideration has to be given
to the size o the original drawings otherwise over
ect the printed quality.
RCAHMS generally works to 50% reduction as astandard.
Drawing materials
RCAHMS survey drawings are intended to provide a
permanent record. To achieve this, Hi-Polymer (eg 6H)
lead penc ils are us ed on a p olyester lm, giving a
waterproo, dimensionally stable archive medium.
Drawing symbols Figure 1
A specic set o conventions and symbols is used to
depict eatures at various scales. A sheet showing the
symbols used by the RCAHMS at various scales is
included on the ollowing page.
The ollowing range o survey scales is used by
RCAHMS:
Location map Figure 17
Should be at an appropriate scale to show the
geographical location o the site.
Topographic or landscape map Figure 16
1:1250 - 1:2500 is used to show eatures within their
topographic setting. The level o detail o man-made
eatures at this scale is limited to outline shapes and
eld
banks, etc. Natural eatures can be illustrated using
hachures or contours.
Site plan Figures 13 -15
1:200 - 1:1000 is used or a site plan to show the
relationship o a group o man-made eatures, such
as a armstead or prehistoric settlement, with related
buildings. This scale allows the illustrator to representsome o the character o the structures, together with
their relative positions also structural elements such as
blockings and straight joints.
A small-scale map to show geographical location.
A larger scale map to show topographic setting o
a building or group e.g. a mill with the mill lade and
river.
A site plan to show the relative positions o a groupo buildings.
A plan and elevation to show the character o an
individual building.
replace.
.
.
.
.
.
Figures 2 & 11
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Figure 1 - RCAHMS Field Survey Drawing Conventions
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Hatching indicates ablocked window
Hatching in thestonework indicates that
replace has beeninserted later
Large ooting stones at the base o the
building have been drawn individually
Wall above sill level
Wall below sill level
Dashed lines indicate that theacing stones o the wall haveallen out and that only wall
core remains
Short triangular hachuresindicate a man-made slope
whichhasbeencuttocreateadrain behind the building
A straight joint indicates that thebuilding has been built in two
phases,thelowercompartmenthaving been added on to the
original building.
Dashed line indicates original lineo wall beore collapse
Cruck slots in wallor roo supporting
timbers
Window opening
Hatching indicateslater addition
Byre drain visibleoor
Door opening
Dashed lines show theposition o the cruck
timber (no longerpresent)
Upstanding walls may be letunshaded at a scale o 1:100
Drain
Figure 2 - 1:100 scale building plan with explanatory captions
Grounded boulders
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Methods of survey
The following pages provide an outline of several survey
methods that can be carried out with simple surveying
equipment:
Field sketch
Dimensioned sketch
Tape and offset survey (extended baseline survey)
Plane table and alidade survey
Each of these methods can provide a very useful record in
its own right. However, often the most effective way to
survey a site is to use a combination of the different
methods.
Field sketch Figure 3 (below)
Undertaking a field sketch provides and extremely
useful way to gain an overview of your site and is an
ideal way to assess the number of buildings and other
structures present, as well as aspects of their construc-
tion, phasing and spatial relationship. A well-drawn field
sketch can provide a very useful record of a site or
building in its own right, or may become the first stage
in the process of producing an accurate scale drawing.
At its simplest, a field sketch need only show building
outlines and orientations (see below). In this example,
building walls standing above sill height are shaded
dark; walls below sill level are stippled; enclosure walls
are shown in outline only. Cruck slots, doorways,
window openings and fireplaces are all shown
and highlighted below.
Always remember to include a north point.
Window
Fireplace
Doorway
Cruck slot
Sub division
Doorway
Figure 3 - Field sketch
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Field sketch. . . . . . annotated Figure 4 (below)
You can increase the value of your sketch by adding notes
and measurements.This will assist your interpretation of
the site when it comes to writing a site description. In this
example, the distance between cruck slots has been
recorded, and the locations of a blocked doorway, window
lintels and a byre drain are all marked.
Equipment required for field sketch:
Paper and pencil
Figure 4
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Dimensioned sketch Figure 5
A dimensioned sketch takes the field sketch one step
further. The aim is to annotate your sketch plan with
accurate measurements to show wall lengths and
thickness. It should include all the necessary dimensions
for someone who has not seen the building to under-
stand it and, if required, construct a scale drawing.
Sketches should be neat, in proportion and large enough
to allow the required dimensions to be clear and legible.
Cumulative measurements, known as running sizes
taken from a single point of origin are preferable to a
series of separate measurements and usually run in a
clockwise direction round a room, or building (see figure
5 opposite for clarification). The origin point for running
sizes should be clearly marked.
Room diagonals and wall thickness measurements should
be included. This method is appropriate for plans, eleva-
tions or details of relatively simple buildings or structures.
Equipment required for sketch survey:
Drawing board, paper and pencil, 30m tape, 5m metal
tape, survey pin, bulldog clips.
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Figure 5 - Example of a dimensioned sketch
Point of origin
Direction of progress
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Tape and offset survey (extended baseline survey)
Tape and offset survey can be used to create accurate,
scaled plans of both small (e.g. a single feature) and larger
areas (e.g. an entire township).
This survey involves establishing a baseline, through, or
parallel to, the features you want to map, and measuring
the distance of the features from this known line (see
figure 6).
To create a baseline, stretch a measuring tape taught
along the ground and hold it in place with pegs.To help
you get a straight line, place survey poles in the ground at
regular intervals so that you can check your line of sight.
The length of your baseline is determined by the size of
the area you want to survey. Once set up on the ground,
plot your baseline though the centre of a sheet of A2
graph paper.
To record points of interest, measure along the tape (or,
baseline), then take a measurement at right angles fromthe tape to the point you wish to record (see figure 5). Plot
these measurements on to your graph paper.The
accuracy of a right angle can easily be checked by basic
triangulation (3-4-5 triangle), or by using a cross-head
ranging pole which allows you to sight a right angle off
your baseline.
Figure 6
Single measurement along an offset is the most
convenient way to plot a point. However, where
the offset is more than 1m, it is more accurate to
use triangulation: measure the distance to the
feature from two separate points on the baseline
and plot where they cross with a compass, or, a
set of dividers (see figure 6 for clarification).
If you are recording large areas, such as a whole
settlement, it is best to set up a series of
baselines across the site.If you are working in a
group,you can rapidly complete a survey in this
way, by dividing the site amongst different
people.
Equipment required for tape-and-offset survey:
Drawing board, graph papers, pencil,compass,
ranging rods (including cross-head), 30m and/or
50m tapes, steel hand tape, land arrows or pegs.
Gridded paper or lm
Primary baseline
Subsidiary baseline
Right angle oset -
subsidiary baseline
3-4-5
Ranging pole
Ranging pole
Cross-site ranging pole
Creating a right angle
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Figure 7 - Example of a tape and offset survey used to capture detail in a single building
Trianglated measurements from
two known points can be plotted
with compass or dividers
baseline
offset
offset
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Methods o survey: plane table and alidade survey Figures 9, 13 -16
This is a method o survey that allows a surveyor to
plot and create an accurate scale drawing on site. The
ts onto the
drawing board.
xed to a
tripod, levelled, and orientated.
An alidade is a sighting device used to observe the
salient points o the site.
Have a good look at the site
Beore you start the survey, time should be taken to
walk round and have a good look at the site or building
that you are going to record. On a building, the obvious
eatures that you would want to record are the corners,
replaces. More subtle
eatures that you would look out or are changes in wall
direction, straight joints, blocked doors or windows,
oorcovering, byre drains.
Select a survey station
Once you have had a good look at the site, you will
select a position or your survey station rom which
you have a line o site to as many o the main points
as possible. It is particularly important to be able to
see corners and places where a eature has a change
in direction. Set up the tripod legs over your selected
survey station.
Prepare the drawing boardlm is taped onto the
drawing board with masking tape.The corners are
lm pulled tight, and then the edges
xed onto the tripod.
Orient the drawing board
When drawing a building you would orientate the long
side o the board so that it is parallel to the long axis
o the building. I possible, or a site plan, you would
oriented the board so that north is up the page. For
all plans it is important to check that the whole site is
t on the board at your chosen scale. A pin
xed point rom
which observations and measurements can be taken.
The pin marks the position o your survey station on
the board. Once the survey has commenced the plane
table should not be moved.
Carry out the survey
The alidade is placed against the pin and used to
observe in turn, selected points. Rays are drawn on
lm and measurements between the pin and the
points taken with the 30m tape. The measurement is
written onto the drawn ray as a record. Subsequently,
each point is plotted along the ray at the selected scale,with a scale rule. Observations and measurements are
taken to as many points as required to allow the shape
to be recorded. These plotted points create an accurate
ramework around which the rest o the plan can be
constructed. This method is most useul or plans o
single buildings or small sites within a radius o 30m
rom the plane table.
Larger sites
For larger sites multiple stations will be required. Thesecond station must be plotted accurately onto the plan
rst station and marked on the ground. It must
rst station (see Figure 13).
Equipment required or a plane table and alidade survey:
Plane table, tripod legs, alidade, spirit level,
30m tape, polyester drating lm, hi-polymer 6H
pencil, masking tape, pin, scale ruler, compass, ranging
rod or sighting, plumb bob.
Figure 8 - A plane table and alidade as supplied by SRP
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Figure 9 - Example o a plane table and alidade survey carried out to record a single building
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Methods o survey: creating an elevation Figure 10 (below) 11 & 12 (opposite)
An elevation is normally created ater a plan o a
building has been completed. An elevation drawn
lm gives a good,
clear representation o a building. In a similar way to a
plan, i the building is not going to be drawn on site, all
measurements can be recorded onto a sketch.
In order to measure elevation heights to add to the
drawing, a datum line must be established across the
ace o the building. The datum is created using a string
xed into position and levelled, using a hanging
string level. This datum line would normally be set at
a height that runs through the middle o the windows
and doors so that tops and bottoms o the eatures can
be measured easily and noted in a clear way. Where
the datum string does not touch the building or it is
cult to take a measurement, a builders spirit level
can be used to transer the datum onto the structure.
A simple chalk line is marked to indicate the datum.
Measuring an elevation is similar to carrying out ax
requires one measurement along the datum line and
one measurement up or down rom the datum line.
I a drawn plan exists, the elevation drawing would be
lm over the plan
the positions o the building corners,
door and window openings or blockings that will be
visible on your elevation. These positions are then
lm on which you are going to draw
your elevation. At these points, where the distance
along the building is known, a 5m steel tape can beused to measure up or down rom the datum line to
obtain the height. The position o the datum line and
o the points are drawn onto your elevation. Once the
detail that has a known plan position has been plotted
onto your drawing, you will have the bare bones o an
elevation.
distance along the datum as well as a height. These
distances and heights can be recorded onto a sketch
survey or a second person can take measurements and
call them out as you draw. Establish a horizontal zero
point on the datum line. In the case o a straight sided
building you might choose the let edge o the building.
I surveying an irregularly shaped building you may
chose a point to the let o any detail that you wish tomeasure in. (A scale rule is marked rom the let so it
is always easier to measure and plot the distances in
the same direction.) A series o points are measured
ne the shape o the building, ground
level, openings, sills, lintels, string courses, chimneys,
roo angles and heights. It is oten easier to get a
measurement or the height o the roo inside the
building.
Once the outlines have been plotted onto the elevation,
it is easier to plot minor detail by measuring rom the
nearest building eature, or example a set o running
sizes can be taken rom the top to the bottom o thewindow to position the joints between the stonework. In
this way all the minor detail that you wish to depict can
be added bit by bit until the elevation is complete.
The section drawing o the Benbecula black house
which was created at the same time as the plan
and elevation has been included to show the kind o
detail that would be recorded on such a drawing. The
methodology or creating a section drawing is not being
dealt with in this guide.
Equipment required or an elevation:
ranging rod, (data board, paper and pencil i doing
a sketch survey),
(plane table, tripod legs, polyester drating lm, hi-
polymer 6H lead pencil, set squares, T square, masking
tape, scale rule, paper and pencil i drawing elevation
on site).
Figure 10 - Example o a sketch survey or an elevation showing some o the sizes which need to measured.
String, line level, chalk, 30m tape, 5m steel tape,
You can now start adding detail or which you need a
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Figure11a Plan and elevation Figure 11b o a Benbecula black house which has been converted to a byre, originally drawnat 1:50 but reproduced here at 1:100
Figure 12 - Section o a Benbecula black house, drawn and reproduced at 1:50
Stone detail may
be completed rom
photography
Thatch
Tur
Rater
Collar
Draininsertedlater
Window converted to a door
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30m
rang
efro
mStatio
n2
30mrange
fromStation1
level
Survey points should be taken on the same side of a feature to avoid confusion.In this case points have been taken on the outside edge of the wall.
,
Cobbling with well defined edge
drawn in on revetted terrace
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Figure 14 - 1:200 scale site plan o a Benbecula armstead drawn with a plane table supplemented with oset measurements.
(The building on the right hand side is also shown in detail at scale 1:100 in Figure 11b on page 15.)
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Figure 15 - 1:500 scale site plan o an Aberdeenshire armstead created using a plane table
Stackstands
Horse-gangplatorm
Upstanding
buildings
Footings o stonebuildings and walls
Buildingvisibleonlyas a slightly raisedbanks o tur
Long dashed hachures areusedtodepictanaturalslope
Quarry
Footings o buildingwith some visibleacing stones
Outcrop
Marsh symbols areused to indicateboggy ground
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Figure 16 - 1:1250 scale landscape map o an 18th century Dumrieshire settlement and eld-system
derived partly rom an Ordnance Survey base plan and rig and urrow added rom vertical aerial photographs.
Stone dyke
Stone walled
buildings
Lines o broad rig & urrows -
added rom aerial photographs
Tur eld banks
Short hachures are used to dep ict
the hollow that denes the trackA series o tur banks anddepressions show an UnenclosedPlatorm Settlement
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