This document discusses the topics of surveying and data for geographic information systems (GIS). It provides background on different types of surveying data, including raster and vector data, and historical surveying techniques used by various ancient civilizations. The key purpose of surveying is also summarized, which is to precisely measure and map land areas and boundaries.

1. CS 128/ES 228 - Lecture 10a 1
Surveying
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2. CS 128/ES 228 - Lecture 10a 2
Data for a GIS
 Raster data
- characteristics?
- sources?
 Vector data
- characteristics?
- sources?
Bottom: Elements of Surveying. U. S. Army, TM 5-232, 1971

3. CS 128/ES 228 - Lecture 10a 3
History of surveying
 Babylon: knew 3-4-5
triangle; developed
base-60 system
 Egypt: used simple
plumb line sighting &
right-angle
instruments.
 Great pyramid: base
square to 0.2 m out
of 230 (0.09%)
Top: The Roman Land Surveyors. O. A. W. Dilke, 1971

4. CS 128/ES 228 - Lecture 10a 4
The motive for surveying?
The priests also said that this king
divided the country among all the Egyptians,
giving each an equal square plot. This was
the source of his revenue, as he made them
pay a fixed annual tax. If anyone’s land were
taken away by the river, he came to the king
and told him what had happened. Then the
king sent men to look at the land and
measure how much less it was, so that in
future the owner would pay the due
proportion.
Herodotus, referring perhaps to Sesostris II of
Egypt (1897-1878 BC). From: Dilke. The Roman
Land Surveyors. Barnes & Noble, NY. 1971.

5. CS 128/ES 228 - Lecture 10a 5
Two types of surveys
 Geodetic survey
- covers distances large enough that
curvature of Earth is significant
- establishes network of precisely
located control points
 Plane survey [not ‘plain’]
- straight lines & angles are sufficient
- what about long, linear features?

6. CS 128/ES 228 - Lecture 10a 6
National Geodetic Survey
Functions:
 defines & manages
the National Spatial
Reference System
 sets standards for
geodetic surveys
 maintains a database
of U. S. geodetic
markers
www.ngs.noaa.gov

7. CS 128/ES 228 - Lecture 10a 7
NGSurvey data sheets

8. CS 128/ES 228 - Lecture 10a 8
Uses for plane surveys
 Land survey
 Engineering or
construction surveys
 Field mapping
Top: Plane Table Mapping. M. Denny. www.pobonline.com...
Bottom: www.tpub.com/engbas/11-24.htm

9. CS 128/ES 228 - Lecture 10a 9
Basic methods
 Locating a point
 Measuring an angle
 Measuring a distance
 Measuring differences
in elevation

10. CS 128/ES 228 - Lecture 10a 10
Locating a point
 Start with known
location or previous
point
 Direction + distance
common for plane
surveys (ex. “metes
& bounds”)
 Two angles common
for geodesy
Principles of Surveying. 2nd
ed. C. A. Herubin, 1978

11. CS 128/ES 228 - Lecture 10a 11
Measuring an angle
 Horizontal angles:
use level, transit, or
theodolite
 Vertical angle: use
transit or theodolite
 Either:
- graduated circles
or
- digital readout
Both: Principles of Surveying.
2nd ed. C. A. Herubin, 1978

12. CS 128/ES 228 - Lecture 10a 12
Angles: readability
 Horizontal & vertical
circles typically
graduated to 1o
for
construction grade
instruments, 5’ or
better for survey
instruments
 Vernier improves
resolution by 10x or
better
 Digital readouts to 5”
or better
Principles of Surveying. 2nd ed. C. A. Herubin, 1978

13. CS 128/ES 228 - Lecture 10a 13
Measuring a distance
 Start with known location or
previous point
 Three techniques:
1. Taping
2. Stadia markings
3. Electronic distance
measurements (EDM)

14. CS 128/ES 228 - Lecture 10a 14
Taping: errors (& fixes)
 Alignment – plumb bob
 Tension – tension
handle (or experience)
 Thermal expansion –
correction tables
 Slope - cosines
Diagram: www.benmeadows.com

15. CS 128/ES 228 - Lecture 10a 15
Stadia markings + rod
 stadia hairs
define a known
vertical angle
 horiz. distance
= 100x vertical
 less accurate
than taping but
faster Both: Principles of Surveying. 2nd ed. C. A. Herubin, 1978

16. CS 128/ES 228 - Lecture 10a 16
Electronic Distance Measurement
 Optical: uses parallax.
Inexpensive but error
≥ 1%
 Ultrasonic: mid-priced.
Accuracy ~ 0.1%
 Laser: moderate to very
expensive. Accuracy 1
ppt or better

17. CS 128/ES 228 - Lecture 10a 17
Measuring elevations
 Known as “leveling”
 Uses a level (optical
or laser) & a rod
 All measurements
are relative (to a
starting elevation)
 Height of
instrument
Both: Elements of Surveying. U. S. Army, TM 5-232, 1971

18. CS 128/ES 228 - Lecture 10a 18
Optical vs. laser leveling
 Optical leveling requires
2 workers
 Laser leveling can be
done alone, but easiest
when rod is equipped
with autodetector
(high/low/on signals)
Top: Principles of Surveying. 2nd ed. C. A. Herubin, 1978
Bottom: Topcon web site

19. CS 128/ES 228 - Lecture 10a 19
Putting it together
Two ways of mapping
a region:
 Traversing – used
to locate specific
features
 Triangulation –
used to establish a
control network
over a region
Both: Elements of Surveying.
U. S. Army, TM 5-232, 1971

20. CS 128/ES 228 - Lecture 10a 20
Types of traverses
Allowable “misclosure”
 First order, Class I:
- 4 mm in 1 km
- 127 mm in 1000 km
 Third order:
- 12 mm in 1 km
- 380 mm in 1000 km
 Land surveys: ???
Both: Elements of Surveying.
U. S. Army, TM 5-232, 1971

21. CS 128/ES 228 - Lecture 10a 21
The total station
 Combines theodolite,
EDM, data logger &
surveying software
 Log ~ 8000 points,
download data to
computer
 Why doesn’t ES have
one???
Topcon web site