Measurements for thematic mapping and for as-built documentation of constructions
description
Transcript of Measurements for thematic mapping and for as-built documentation of constructions
![Page 1: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/1.jpg)
Measurements for thematic mapping and for as-built documentation of
constructions
Methods:
1. spatial polar method
2. photogrammetry
3. laser scanning
4. remote sensing
5. GPS
1
![Page 2: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/2.jpg)
Thematic mapping
• Thematic map is the map of large scale with special content. – Map of plant (factory) 1:200
– Technical map of city 1:1000
– Map of railways
– Road map
– Map of forest 1:5000
• Special content: engineering network, equipments of railwais (rails, switch,...), technical infrastructure, vegetation,...
2
![Page 3: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/3.jpg)
1. Spatial polar method
• coordinates Y, X, Z of a point are determined
• a network of survey stations for detailed measurement has to be created in the area in which the mapping is carried out
• determination of survey stations coordinates – methods presented in 2nd lecture (e.g. traverse)
3
![Page 4: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/4.jpg)
Principle
Measured:
slope distance d
horizontal angle ω
zenith angle z
X
Y
Z
P
z
d
S
4
![Page 5: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/5.jpg)
s … horizontal distance
Problem: there is not a possibility of a bearing measurement therefore the horizontal angle ω between the orientation point O and unknown point P is measured. The bearing SO is calculated using known coordinates of these points and then the bearing SP is calculated.
x s.cos d .sin z.cos
y s.sin d .sin z.sin
z d .cos z
5
![Page 6: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/6.jpg)
X
Y
S
O
Ps
P S SP SO
P S SP SO
X X s cos( )
Y Y s sin( )
6
![Page 7: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/7.jpg)
z
d
vp
cv
P S p cZ Z v d .cos z v 7
![Page 8: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/8.jpg)
Record of measured data
1. field book
2. field sketch
8
![Page 9: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/9.jpg)
Field book• number of the survey station • measured orientation angle • height of the instrument vp
For particular detailed points:• height of the target vc • measured values of d, ω, z
The best field book is a table with needed data. There is also a possibility of measured data registration at a memory card of a total station (if a total station is used). 9
![Page 10: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/10.jpg)
Field sketch
14001
4002
4003
4004
2
3
4
5
13
14
15
16 17
18
19
98
76
11
1021
22
20
12
23
24
10
![Page 11: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/11.jpg)
Equipment for the spatial polar method
1. a theodolite and a measuring tape
2. a tacheometer with stadia lines
3. a tacheometer with an electronic distance meter (total station)
11
![Page 12: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/12.jpg)
Measurement with a theodolite and a tape
• if better equipment is not available
• for distances shorter than length of the tape (mainly in interiors)
• a horizontal distance is measured by the tape it is used if the altimetry is not measured (only coordinates Y, X are determined)
12
![Page 13: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/13.jpg)
Tacheometer with stadia lines
• equipment = theodolite + rod
• a theodolite is placed at the survey station, a rod is set on the determined point
• upper, middle and lower readings are read on the rod, a horizontal and a zenith angles are measured
• horizontal distance D and height difference h are calculated:
2D k l sin z
Dh
tan z
13
![Page 14: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/14.jpg)
Tacheometer with electronic distance meter
• most widely used nowadays• distance is measured using a prism as a target or
using a reflectorless distance meter • total stations enable measurement, registration
and measurement processing (calculation of coordinates Y, X, Z)
• advantages = 1. high accuracy 2. great range of a measurement
(more than 1 km), therefore less survey stations are necessary
14
![Page 15: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/15.jpg)
2. Photogrammetry
• method which makes use of photos to obtain measuring information
• analogue or digital photos are used
• equipment – non-proffesional cameras (for simple tasks with low requirements for accuracy) or special photogrammetric cameras
• photo = central projection of reality to the plane of photograph
15
![Page 16: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/16.jpg)
16
![Page 17: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/17.jpg)
These parameters have to be known for determination of a shape, size and spatial position of an object :
1. elements of interior orientation: they define internal relations in the camera,
2. elements of exterior orientation: they determine relation between the camera and the object.
17
![Page 18: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/18.jpg)
Elements of interior orientation
a) camera constant (calibrated focal distance f)
b) position of the principal point of photograph = position of the view axis and photograph plane intersection point (x0, y0)
c) lens distortion = object-lens deficiency
18
![Page 19: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/19.jpg)
Elements of exterior orientation
a) centre of projection position = entrance pupil (X0, Y0, Z0)
b) turning of the photo expressed by rotational angles ω, φ, κ (rotational angles of axis x, y, z)
If the elements of orientation are not known, it is possible to calculate them using so-called control points = points whose coordinates are known.
19
![Page 20: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/20.jpg)
Photogrammetry:
1. single image photogrammetry
- only plane coordinates of an object are determined (Y, X)
- it is used if the measured object is plane, e.g. flat front of a building
2. multi-image photogrammetry
20
![Page 21: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/21.jpg)
Multi-image photogrammetry
• spatial coordinates of the object are determined (Y, X, Z)
• stereophotogrammetry (two-image photogrammetry) is used most frequently – 2 photos are provided and analysed:
formerly analogue instruments
nowadays digital methods – spatial perception is created by means of a display and special glasses
21
![Page 22: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/22.jpg)
22
![Page 23: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/23.jpg)
23
![Page 24: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/24.jpg)
Photogrammetry:
1. terrestrial photogrammetry
survey station is stationary elements of exterior orientation can be determined
reach about 500 m
accuracy from cm to dm
2. aerial photogrammetry
camera is in plane terrestrial control points have to be used
accuracy from dm to m 24
![Page 25: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/25.jpg)
25
![Page 26: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/26.jpg)
3. Terrestrial laser scanning
• new technology based on the principle of the spatial polar method
• instruments = laser scanners which enable a non-selective measurement of a huge number of points on the object surface (thousands points per second)
• result of a measurement = point cloud whose parts are replaced by a plane, sphere, cylinder etc. (modelling)
26
![Page 27: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/27.jpg)
Non-selective measurement
27
![Page 28: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/28.jpg)
• Range of scanner measurement is usually from 1 to 1000 m (terrestrial scanners)
• Accuracy is in range from 1 mm to 50 mm
• Results: point cloud, CAD model, TIN
• Use – documentation of the present condition of an object (e.g. historical monument), volume determination,...
• Advantages: fast measurement, large amount of data (millions points)
• Disadvantages: large amount of data (millions points), data processing, software 28
![Page 29: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/29.jpg)
Laser scanners
29
![Page 30: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/30.jpg)
30
![Page 31: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/31.jpg)
Earth surface – scan
31
![Page 32: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/32.jpg)
Earth surface – contour model
32
![Page 33: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/33.jpg)
Rocky massif – scan
33
![Page 34: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/34.jpg)
Rocky massif – 3D model
34
![Page 35: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/35.jpg)
Aerial laser scanning
• the same principle as the terrestrial (previous) one
• more robust and efficient scanners are used (plane is moving during scanning)
• aerial scanners are usually line scanners and the other dimension is created by the plane motion
• accuracy in cm• aerial photogrametry is fill up by this
technology (advantages = speed and flexibility) in some situations 35
![Page 36: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/36.jpg)
Aerial laser scanning
LE
TA
DL
O
36
![Page 37: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/37.jpg)
Town 3D model created by laser scanning
37
![Page 38: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/38.jpg)
4. Remote sensing• satellite images are created, analysed and
processed thematic maps creation • information is obtained using electromagnetic
radiation
1. passive data acquisition system: only receiving of radiation, thermal radiation of the Sun or of the Earth is used,
2. active data acquisition system: radiation is emitted and then it is reflected by the investigated object, the reflected radiation is recorded, artificial source of radiation is used (radar)
38
![Page 39: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/39.jpg)
Every object (e.g. terrain without vegetation, vegetation, water etc.) has its characteristic reflectivity. If object’s reflectivity is known, the type of object can be determined by receiving signal processing.
accuracy about 1 m
39
![Page 40: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/40.jpg)
5. GNSS – global navigation satellite system
• GNSS are used for navigation in real time, and it is possible to use it for geodetic measurements.
• satellite passive telemetric system • satellites circle the Earth on orbits in specific height• all satellites emit coded information about their positions
and sending time• satellites’ signals are received by means of a special
instrument processing information (= calculate distance between the satellite and the receiver)
40
![Page 41: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/41.jpg)
• calculation results from knowledge of the satellite signal speed and the difference between sending and receiving time
• signals of 3 satellites at least are necessary for positioning (geographic longitude and latitude are determined)
• signals of 4 satellites at least are necessary for determination of position and height
• We need teoretically 3 satellites, but we must determine the time error of receiver – it is fourth unknown
• originally GPS was military navigation system of United States Army, it has been available for civil users since 1990s
41
![Page 42: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/42.jpg)
GPS
42
![Page 43: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/43.jpg)
GNSS signal processing1. Navigation GNSS (the simplest) accuracy several m2. Differential GNSS algorithm is the same as previous one, in addition
several corrections are introduced accuracy about 1 m3. geodetic GNSS 2 special instruments are necessary, computational
procedure is sophisticated, only positional differences are determined
accuracy in cm accuraccy in mm for distances shorter than 10 km and
for long observations (12 hours)43
![Page 44: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/44.jpg)
RTK method
RTK (real time kinematic) – two instruments, the first (base) is placed on known point, the second (rover) is placed on measured point.
Measurement is in real time. It is necessary to have permanent direct data connection (GSM) between base and rover.
Nets of reference stations are operated (CZEPOS, WRS NOW, TOPnet) – advantage – you need only one instrument.
44
![Page 45: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/45.jpg)
NAVSTAR GPS
Structure of the systemCosmic segment 24 satellites circle the Earth on 6 orbits in height of 20200
km (now 32), all satellites emit coded information about their positions and sending time.
Control segmentTerrestrial control centers for control and revision of space
segment.Users segmentUsers receive the satellite signals by receiver and determine
their position and time.45
![Page 46: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/46.jpg)
Another systems
Russia – GLONASS – 21 satellites
EU – GALILEO – 4 satellites
China – BEIDOU (COMPASS) – more than 10 satellites
Local GNSSJapan – QZSS – 3 satellitesIndia – IRNSS – 7 satellites
46
![Page 47: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/47.jpg)
47
![Page 48: Measurements for thematic mapping and for as-built documentation of constructions](https://reader035.fdocuments.net/reader035/viewer/2022062800/56814115550346895dacd99f/html5/thumbnails/48.jpg)
48