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British Columbia Institute of Technology

Geomatics Department

B. Tech. Program

Geomatics Project:

Comparison of Laser Scanner and Total Station Survey Methods: Analysis of Time and Accuracy

for Building Modeling

By: William Oleksuik

and

Eric Sankey

Prepared as a requirement for: GEOM 8230

March 31, 2014

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Acknowledgements

We would like to thank the following people for their assistance and guidance throughout

the course of this project.

Mark Hird-Rutter: Mr. Hird-‐Rutter originally introduced us to High Definition Surveying

(HDS) and point cloud modeling in SURV 4476. He is also our project Mentor and helped us

every step of the way. From helping to select a topic, facilitating the scanner rental and

insurance, and providing Cyclone troubleshooting advice, Mark has been a huge part of the

successful completion of this project.

Keith Belsham: Mr. Belsham, Technical Sales Representative, at Spatial Technologies in

Vancouver, has provided the Leica C10 scanner, bipod, tripods, tribrachs, and HDS targets

required for our field work. He was kind enough to wave the $500 per day rental cost of

this equipment, which was an astonishing gesture of generosity. Without Mr. Belsham’s

support we would have likely used BCIT’s Cyrax laser scanner. Using the Cyrax would have

caused the project to be much less applicable to modern surveying.

Dave Martens: Mr. Martens was very helpful in the selection and refinement of the project

topic. His advice regarding the scope, planning and execution of the project was invaluable.

He also assisted us during the fieldwork when we were having issues with the C10 scanner.

Dr. Joan Yau: Dr. Yau was the original instructor of GEOM 7230 during which we selected,

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planned and presented our project outline. Dr. Yau provided us with the framework for

writing successful technical reports and also provided useful feedback throughout the

early stages of the project.

Executive Summary

The constant evolution of technology has contributed to a greater variety of on-‐the-‐

job tools available to Geomatics technicians. Different survey tasks are now able to be

conducted using wide variety of survey methods. One survey technology, which has not

been utilized frequently by surveyors, is the laser scanner. The reader of this report will be

able to directly compare an up to date laser scanner with a commonly used total station.

The increase in newer 3D scanner’s functionality and speed could give surveyors more

options rather than only using traditional survey methods.

A common survey task in which each method can be easily compared is the

modeling of a building. Features of a building can be picked up using either a total station

or a scanner and the resulting data can later be modelled. Examining the processes and

resulting data of each survey method for such a project, involves many parameters. Time

and accuracy comparisons of the two methods are the main focus of this report. A

comparison of the final products derived from the two survey methods is presented in this

report as well. Further examination of cost, convenience, and the amount of collectable

data regarding total station and scanning procedures will allow for a thorough and

complete overview. The final analysis of total station and high definition survey (HDS)

methods can also be applied theoretically to more survey situations than the one provided.

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Table of Contents page#

Acknowledgements ………...………………………………………………………………………… ii

Executive Summary ……………..…………………………………………………………………… iii

Table of Contents ………………………..…………………………………………………………… iv

List of Tables & Figures …………………….……………………………………………………… v

1.0 Introduction & Background ………….…………...………………………………………… 1

2.0 Goals & Objectives ……….……………………………………………………………………… 2

3.0 Methodology …….………………………………………………………………………………… 3

3.1 Expectations of Total Station Method ..………………………………………………… 7

3.2 Expectations of Laser Scanner Method ………………………………………………… 8

4.0 Execution …….………………………………………………………………………………...…… 9

4.1 Total Station Field Survey Summary …………………………………………….……… 9

4.2 3D CAD Drawing Summary ………………………………………………………….……… 10

4.3 Scanner Field Survey Summary …………………………………………………………… 11

4.4 HDS Modeling Summary ……………….…………………………………………………..… 12

4.5 Elevation check Summary ……………..………………………………………………..…… 14

5.0 Results & Analysis. …..………………………………………………………………………….. 15

5.1 Accuracy Analysis ……………………………………………………………………..………… 23

5.2 Point Analysis………………………………………………………………………………………. 24

5.3 Surface Accuracy Analysis …………………………………………………….……….……. 27

5.4 Time Results & Analysis……………………………………………………….……….……… 31

5.4.1 Total Station Survey Time Results………………………………………..…..………… 31

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5.4.2 Laser Scanner Survey Time Results…………………………………………………… 32

5.4.3 Comments & Analysis……………………………………………………………………….. 33

5.5 Analysis of Other Factors…………………………………………………………….………. 33

5.5.1 Cost…………………………………………………………………………………………………. 32

5.5.2 Data Volume……………………………………………………………………………………. 33

5.5.3 User-‐friendliness……………………………………………………………………………… 33

6.0 Conclusions...………………………………………………………………………………………. 35

References…………………………………………………………….………………………………….. 37

List of Figures Figure 2.1 Survey Building Site …..……………………………………………………………. 3

Figure 2.2 Survey Site Map with Aerial Photo. ………………………………………….. 4

Figure 2.3 Survey Design Options. …………………………………………………………… 5

Figure 4.1 Overview of Traverse Data. …………………………………………………….. 10

Figure 4.2 Multi-‐planar Surfaces from Total Station Data. ………………………… 11

Figure 4.3 Cyclone Patch Statistics. ………………………………………………………….. 13

Figure 4.4: Cyclone Region Grow Example. ………………………………………………. 14

Figure 5.01: Total Station 3D Model Screenshot. ………………………………………. 15

Figure 5.02: HDS 3D Model Screenshot. …………………………………………………… 15

Figure 5.11 Typical Building Roof Corner in Reality and in Cyclone. ………….. 26

Figure 5.12: Point Cloud Noise & Building Imperfections. …………………………… 28

Figure 5.13 Plane Equation and Definition Formulae. …………………………………. 29

Figure 5.16 Sketch of Plane Locations. ……………………………………………………….. 30

Figure 5.18 Point to Plane Offset Screenshot. ………………………………………….….. 31

List of Tables Table 5.03 Total Station Survey Coordinates. …………………………………………….. 17

Table 5.04 Laser Scanner Survey Coordinates. ………………………………………….. 18

Table 5.05 Comparison of Laser Scanner and Total Station Coordinates …….. 19

Table 5.06 Levelling Elevations. ………………………………………………………………... 20

Table 5.07 Comparison of Total Station and Levelling Elevations. ………………. 21

Table 5.08 Comparison of HDS and Levelling Elevations. …………………………… 22

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Table 5.09. Total Station Control Error Ellipses. ………………………………………… 23

Table 5.10 Resection Results. …………………………………………………………………….. 25

Table 5.14 Total Station Data: Plane Definition Parameters. ……………………….. 29

Table 5.15 Cyclone HDS Plane Definition Parameters. ………………………………… 30

Table 5.17 Comparison of Normal Vectors and Point-‐to-‐Plane Offsets. …….…. 30

Table 5.19: Cost of Hardware and Software for Each Survey Type. ………….….. 33

Tables 6.1 Summary of Results. ………………………………………………………………... 35

List of Appendices page#

A Field Notes. ……………………………………………………………………………………. 39

B Least Squares Analysis Results. ………………………………………………………. 46

C Cyclone Registration Results. ………………………………………………………….. 49

D Raw Point Cloud File ……………………………………………………………………… 51

E Leica C10 Traverse File. ……………..…………………………………………………. 51

F Final AutoCAD Model. ……………………………………………………………………. 51

G Final HDS Model. …………………………………………………………………………… 51

H Adjusted Total Station Point File. ……………………………………………………. 51

I Complete Least Squares Analysis Output File. …………………………………. 51

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1.0 Introduction & Background

As survey technology rapidly advances, like it has in recent years, the variety,

complexity, and procedures of modern survey tasks has changed as well. HDS technology

has not been used commonly by surveyors due to its high pricing, time consuming

processes, and higher levels of noise. 3D scanning technology also requires that the user be

familiar with the scanner and 3D modelling software. These setbacks have made laser

scanning a less than ideal solution to use in common survey procedures. There are two

general types of laser scanners, time-‐of-‐flight and phase based. Time-‐of flight scanners

typically have longer range capabilities, but slower data collection speeds compared to

phase based scanners which typically offer faster and short-‐range data collection. Current

HDS technology is now less expensive, more precise, versatile, and easier to use than in the

past. Some scanners even contain built in traverse functions to allow the user to collect

large amounts of data independently from other survey methods. The scanner chosen for

this project is a time-‐of-‐flight style in which the speed has been increased, but its range has

been reduced. Now that HDS technology has advanced, it is more accessible and there is

more possibility for it to become a familiar tool within the survey industry.

The authors of this project will demonstrate the capabilities of an up to date 3D scanner

in comparison with the capabilities of a typical total station. The main aspects of each

method which are to be compared include:

• Time taken to complete:

○ Data collection in the field

○ Data processing in the office

● The achievable horizontal and vertical accuracy of:

○ Building corners

○ Surfaces definition

○ Singular control points

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This project aims to determine the amount of time and level of accuracy that can be

expected from using HDS technology and conventional survey methods. The two

disciplines will be evaluated in a construction as-‐built survey scenario. The advantages and

disadvantages of each option will be explored in an in-‐depth and hands-‐on analysis of HDS

and traditional survey methods.

2.0 Goals & Objectives

One of the primary goals of this project was for the authors to gain an

understanding of 3D scanning and its associated software. In this particular case, the

software being utilized is Leica Cyclone version 8.0.2 and the 3D scanner being used is the

Leica ScanStation C10. Reaching such a goal, and familiarizing oneself with 3D scanning

and modeling could prove to be a favourable career asset.

The main objectives for this project include providing:

● A reliable and accurate analysis on the time it takes to conduct 3D scanner and total

station survey methods. In this report, it will be clear which method took more time

collecting field data, which method took longer modeling the collected data, and

which method was more time efficient overall.

● A reliable and accurate analysis on the achievable accuracy of 3D scanner and total

station survey methods. This research document will clearly indicate which method

was more effective.

● Categorical comparisons which extend slightly beyond the intended scope of the

project. For example, comparisons of the data volume, user-‐friendliness and the

price of the hardware and software.

● An easily interpretable final comparison which can be used by industry

professionals.

The final objective for this research project is to meet the requirements for the BCIT

course GEOM 8230 in 2014.

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3.0 Methodology

This section will explain the general methods selected in the planning stages of the

project. The contents of this section include the selection and planning of a survey area, as

well as expectations of each survey method. Basic details and procedures will also be

covered.

The level of detail of the selected site is an important factor in the comparison of

laser scanner and total station surveys. A building site with basic details and building

features would heavily favour the total station survey in terms of field data collection

speed. A large, complex and highly detailed subject area would favour the laser scanning

method. The limitations of the project that were set out in GEOM 7230 included only

having a maximum of three days of fieldwork, and the C10 scanner rental lasted for only

two days. Due to these reasons, a large and complex building was not chosen. A relatively

simply shaped building with mainly linear features and with some fine details such as

windows, pillars, and overhangs was selected to balance the inherent strengths and

weaknesses of the two survey methods and set up an unbiased, “even playing field”.

The selected area was BCIT’s NE28 building and its immediate surroundings. The

building, which is shown in Figure 2.1, is concrete and cinder block construction and most

of these surfaces are painted white: “surfaces of lighter colour with higher reflectance

provide the most favourable results in terms of high point density and minimal noise”

(Clark & Robson, 2004).

Figure 2.1: Survey Building Site

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The site was conveniently close to several Government Control Monuments (GCP),

one of which is part of a High Precision Network (HPN). The HPN monument tablet

marking is 82H5025 and has standard deviations of +/-‐ 2 mm in Northing and 1 mm in

Easting (GeoBC, 1994). This monument was used as a starting traverse point for field

work, and its coordinates were held fixed for the coordinate system.

Figure 2.2: Survey Site Map with Aerial Photo

The design of the total station method survey was to traverse from the HPN

monument, back sighting another GCM (tablet marking 82H4975) to the South, to and

around NE28 with four instrument setups near each of the building corners. The geometry

of this survey involves using oblique angles for the reflectorless EDM shots. The two main

options for setup locations are displayed in Figure 2.3. Oblique angles to the building could

have been reduced by using the dashed-‐line traverse arrangement, however it would

increase the distance of EDM measurements to building corners, thus increasing noise.

Furthermore, oblique angles do not affect laser scanner results. According to Clark and

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Robson “the number of points captured (area under the curve) decreases with an increase

in incident angle. The charts show that the normal distribution improves as the incidence

angle is increased” (2004, p.6). To compensate for oblique angles with the total station, an

angle-‐offset can be applied after the distance is measured to an object placed perpendicular

to the building feature being measured. Since the same instrument stations are being used,

the incidence angle will be the same for both survey methods.

Figure 2.3: Survey Design Options

In order to compare the time and accuracy of the two survey methods in question,

the field procedures, the subject of the survey, and the recording of time must be carefully

planned. The building scan was to be completed several times before the field time was

actually recorded. This ensured that proficiency with the scanner was adequate, allowing

for an accurate time comparison. Practice models of the Cyclone data were to be created in

order to obtain familiarity with Cyclone and modelling. Becoming familiar with the

software was essential in providing an accurate time comparison of the office work as the

authors were much better acquainted with AutoCAD Civil 3D.

Generally, to obtain high-‐accuracy measurement results, more time should be taken

and more caution exercised. This makes the comparison of time AND accuracy challenging.

The surveys were planned so that a reasonable amount of time was spent in the field with

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reasonably precise and common instrumentation to produce reasonably high quality

results. The procedures were selected and omitted based on formal education and

previous work experience. Some examples of procedures used and not used are listed

below:

Used:

● A 2” Total Station

● Dual-‐faced measurements on control points

● Least squares adjustment

● Coordinate system based off of HPN monument (82H5025)

● Closed Loop traverse

● Scanner resection

Not used:

● Forced centered tribrachs

● High-‐precision optical plummets

● Scanner traverse (attempted)

● Arbitrary coordinate system

● Cloud to cloud registration

● True RGB colours

The analysis of reflectorless EDM shots will be difficult because no true and absolute

location of the building’s features can be obtained; All measurements are subject to

uncertainties. Surveying with the total station involved angle-‐offset shots and the scanner

survey involved no precise pointing at all to the building. The confidence regions for the

surrounding control points are obtainable through least squares analysis, and this

confidence will be interpolated to the building’s position based on the published precision

of the instruments.

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Other independent checks were performed to obtain additional redundant and

reference results. The vertical accuracy of the total station and the laser scanner can be

easily checked by running a level loop from the HPN monument to the control points and to

some building features. The C10’s traverse function will also be explored as a completely

independent survey.

The office portion of the project will require lots of practice and familiarization with

the software’s 3D drafting and modeling procedures before accurate and time-‐efficient

deliverables can be produced.

3.1 Expectations of Total Station Method

Leica 802 Specifications:

● Angular s.dev: +/-‐ 2”

● EDM (IR) s.dev: 2mm +/-‐ 2ppm

● EDM (RL) s.dev: 3mm +/-‐ 2ppm

● Beam Divergence 1.5 x 0.5 milli-‐radians (Leica Geosystems)

Expected Advantages:

Total stations are incredibly versatile instruments with near limitless measuring

capabilities. Advances in total station technology such as robotics and GPS integration have

increased the efficiency and accuracy of field surveys. Surveying with a total station allows

the surveyor to choose individual points to measure and each shot is made with relatively

high precision in angular and distance measurements as seen above.

The 3D drafting is relatively simple: connecting the appropriate points with

polylines and creating surfaces between the lines. Less time is spent managing large

volumes of data and navigating through a complicated point cloud.

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Expected Disadvantages:

When using a total station to measure complex features, taking many individual

shots can be time consuming and tedious. This method would also be more prone to

human error and blunders. Recording data in field notes allows for translation errors

when recording point numbers. When picking up features with a total station, it is up to

the surveyor on the job to remember which areas of the building have been picked up. This

allows for possible error in memory. There is also a lack of redundancy when defining

surfaces, small sample sizes means less confidence in the results. Conspicuous features or

abnormalities can be overlooked and omitted from the data and very accurate and clean

field notes must be made to keep track of point numbers (see Appendix A).

3.2 Expectations of Laser Scanner Method

Leica C10 Specifications:

All ± accuracy specifications are one sigma (1σ, 68%) unless otherwise noted.

● Accuracy of single measurement: Position: 6 mm, Distance: 4 mm (at 1 m -‐ 50 m

range)

● Modeled surface: +/-‐2 mm (Subject to modeling methodology for modeled surface)

● Target acquisition: 2 mm standard deviation

● Angle (horizontal/vertical): 12" / 12"

● Beam Divergence: 240 micro-‐radians (Leica Geosystems)

Expected Advantages:

When using the Laser scanner, simplified field work procedures are expected. The

field notes would be much less detailed since images of the building would be automatically

taken with the scanner hardware. All features of the building would also be visible in the

Cyclone uploaded point cloud. Features are unlikely to be left out of the dataset making

additional site visits unnecessary. The modeled surfaces include thousands of points each

that fit user-‐defined tolerances. This volume of data would, theoretically, be able to

provide very detailed building site analysis.

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Expected Limitations:

Modern scanners and associated modeling software are expensive. Also scanners

are not ideal for setting control. Modeling software requires fast-‐processing hardware, and

certain functions take more processing time and may cause the program to crash. The

edges of objects are not directly measured; two surfaces are defined and then extended to

create a corner. The spacing of points increases with the distance from the scanner making

it possible for thin, vertical objects to have little to no points. “Features such as building

corners or edges falling between two successive angular increments of the laser beam …

may not be completely measured by the laser beam due to its spot size” (Chow, 2007).

4.0 Execution

This section will describe the details of carrying out the planned surveys. The

contents of this section include summaries of field and office procedures for both

traditional and high definition survey methods.

4.1 Total Station Field Survey Summary

The total station survey began at a nearby Government Control Monument baseline

using monuments 82H5025 and 82H4975. A closed traverse was then conducted around

building NE28. At each of four instrument stations around the building, shots were taken

to 3-‐4 common points that were to be used for control points for the laser scanner

resection and for redundancy in the least squares network adjustment. Reflectorless shots

were taken at the building envelope corners and at other significant corners and building

faces so that a detailed model could be created. The resulting building data collected with

the total station is shown in Figure 4.1. This figure does not show traverse and side shot

points. Field notes included sketches to keep track of approximately 350 point numbers

(See Appendix A).

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Figure 4.1: Overview of Traverse Data

The time keeping was done in a way that simulates a smooth flow of work from

experienced surveyors. Field time does not include:

● Physically setting control points (nails & cross-‐cuts) used for both, cancels out

● Reconnaissance (Taking photos & planning)

● In-‐field strategy discussion

● Levelling elevation check.

Keeping track of point numbers in the field notes required extremely detailed

sketches since there were hundreds of points in a relatively small area. The point

numbering of common points also created confusion during the least squares analysis.

There was one area where building shots to a large wall surface were missed.

4.2 3D CAD Drawing Summary

The points measured by total station are held fixed, however they show the

imperfections of the building’s faces more realistically as multi-‐planar surfaces. (See Figure

4.2) Since the model of the total station data is produced using 354 points as opposed to

approximately 6.4 million, the resulting drawing is defined much differently than the

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cyclone drawing. Surfaces were created using specific points picked out and shot in the

field. Defining a surface from the total station data promised high accuracy of the building

corner points as these exact points were picked out and shot in the field.

Figure 4.2 Multi-planar Surfaces from Total Station Data

Figure 4.2 Multi-‐planar Surfaces from Total Station Data The drafting of a 3D model

from the total station data was done in Civil3D 2012. From the adjusted points and using

field note sketches and photos for reference, 3D polylines were created. Then, “loft” planar

surfaces were created from the polylines and the surfaces were extended to meet each

other. Each surface is defined by 3 to 4 points and some surfaces are connected to other

surfaces where they would be all one surface in the Cyclone point cloud’s model. In Figure

4.2, the 5 vertical pillars and the uppermost horizontal header are all one surface, but it is

defined by multiple planes. Similarly to the fieldwork, the time keeping simulated a smooth

flow of work. Office time does not include:

● Title-‐block and plotting preparation

● Least squares analysis: used for both methods, cancels out

4.3 Scanner Field Survey Summary

Once the control file was adjusted and imported into the C10’s memory, the scanner

was set up at the same 4 instrument stations. Using its resection program, 4-‐5 targets were

measured and the positions of the scanner were calculated. Only sub-‐centimetre standard

deviations and residuals were accepted. Several points had to be added and removed from

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the resection calculations to achieve the desired statistics. At Station #1, residual errors

and standard deviation of the calculated set-‐up point were greater than 1cm in the vertical.

Resection station coordinates varied up to 6 cm in elevation when these stations were

removed from the calculation. This may indicate a weighting issue in the software.

A medium definition scan with a custom window (rather than a full 360x270) was

selected to save time and disk space. Similarly to the total station survey, the timekeeping

simulated a smooth flow of work. The field time does not include:

● Analysis of resection results

● Scanner boot-‐up (approx. 3 minutes each)

● In-‐field strategy discussion.

4.4 HDS Modeling Summary

Several practice models were created in an effort to become familiar with Cyclone

modelling before recording time. Both authors spent many hours working with the dataset

(For raw data see Digital Appendix D). The main challenge in point cloud modelling was

data management. Isolating points on an individual surface was important so that points

from other surfaces would not be included in surface definition. Hiding large volumes of

points often had processing delays as did the region grow calculation process. Once the

authors were comfortable with the software, a final model was created and the time taken

to create it was recorded. The final modeling process that was used is as follows:

The 3D point cloud modeling began with importing the scanner data into Cyclone

version 8.0.2. The data was automatically registered into a complete scan world, but some

control point elevations were off by as much as 3 cm in elevation. The adjusted control file

was imported and re-‐registered with sub-‐cm errors. For complete registration results, see

Appendix C. Once this was done, adjustments within cyclone were made in order to make

the modeling process easier. Limit boxes were set so that point cloud points outside the

area of interest did not interfere with the modelling. Reference planes were set on

important plane surfaces so that modelled building parts could easily be extended to them.

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These planes included the roof and the ground surface. Once the cyclone model had been

set up in a way that provided for the most time efficient modelling, the modelling of the

actual building was conducted.

The main features of the building were modelled first, this included building

columns, walls, and roof. After this, the more detailed parts of the building, such as the

windows and the doors, were modelled. All major features were modelled using the region

grow command, as this best fit a patch to the building surface based on thousands of points

and user-‐defined tolerances (patch tolerances were set to 0.005m). The resulting patches

from the region grow were not uniformly shaped. Using alignment, extension, rectangular

patch shaping, and extrusion commands, the initial patches were cleaned up and fit to each

other.

All of the points on a surface are used in attempt to define one true plane. Several

points are initially selected manually by the operator. From the hand-‐picked points, a

plane is defined and using user-‐defined tolerances, the ‘region grow -‐ patch’ command

extends the plane and incorporates all points that fit the tolerances. Cyclone will display

statistics for the sample of points for each surface as seen in Figure 4.3 and Figure 4.4.

Figure 4.3: Cyclone Patch Statistics

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Figure 4.4: Cyclone Region Grow Example

The traverse function of the C10 was a very attractive feature because it required

minimal control (1-‐2 points as a baseline) to be placed via total station. The scanner could

be used completely independent of a total station. This feature was to be used in a scanner

traverse in order to further compare scanner capabilities with a total station. The

monument baseline used was approximately 50 meters in length and consisted of a HPN

monument and a control nail placed during the total station traverse. While occupying this

baseline, backsighting errors were in the order of 1-‐2mm horizontal and 5mm vertical.

Once the next leg of the traverse (approx. 50m) was set and occupied, the horizontal

backsight errors were acceptable and the vertical error was 23mm. Upon starting over,

checking and double checking the height of instrument (HI) and height of target (HT)

measurements, the vertical error only improved to 15mm at the same point. This

magnitude of error over such a short distance was unacceptable and the traverse was

abandoned. For raw traverse data see Digital Appendix E.

4.5 Elevation check Summary

The initial evaluation of the field data, by comparison of the least squares analysis of

total station data and the scanner resection results, revealed elevation values that varied

up to 32 mm. In order to resolve these height discrepancies, a level loop was conducted

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starting from the high precision monument to all the control points in the network. This

was done using a Leica DNA03 (precision: 0.3mm/km double-‐run). When the elevation of

the building corners became a concern as well, another level loop was performed using a

Leica Sprinter 100 (precision: 2mm/km double-‐run). A digital rod was used for all ground

checks and a pocket tape, pulled down from each roof corner, was used to check roof

elevations (see Appendix A).

5.0 Results and Analysis

Two 3D models were created, both in .dwg format. The following Figure 5.01 and

Figure 5.02 are screenshots from the CAD files. The two building models are similar in

appearance, but their definitions and origins are very different. The complete drawing files

are found in the Digital Appendices F and G.

Figure 5.01: Total Station 3D Model Screenshot

Figure 5.02: HDS 3D Model Screenshot

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The coordinates tabulated in Table 5.03 are the total station survey results after a

least squares adjustment in which the standard deviation of unit weight was 1.06637. The

complete least squares analysis results are found in Appendix B. The coordinates found in

Table 5.04 represent the points extracted from the 3D model made in Cyclone from four

registered point clouds. The registration results are found in Appendix C. The subtraction

of total station-‐based point coordinates from corresponding HDS-‐derived point coordinates

are listed in Table 5.05.

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Total Station Coordinate Results

Instrument Setup Points

Pt. ID Northing (m) Easting (m) Elevation (m) Description 1 5455508.078 500028.203 25.853 SE setup 3 5455507.527 499986.774 25.879 SW setup 5 5455533.463 499986.963 25.877 NW setup 7 5455534.133 500027.215 25.854 NE setup

Critical Exterior Building Points Pt. ID Northing (m) Easting (m) Elevation (m) Description 1000 5455512.033 500023.486 25.870 SE ground 1082 5455512.062 499989.671 25.886 SW ground 1162 5455531.456 499989.697 25.853 NW ground 1300 5455531.435 500023.515 25.836 NE ground 1001 5455512.028 500023.487 29.257 SE roof 1083 5455512.042 499989.676 29.340 SW roof 1163 5455531.463 499989.698 29.354 NW roof 1301 5455531.449 500023.515 29.322 NE roof Surrounding Control Points Pt. ID Northing (m) Easting (m) Elevation (m) Description 103 5455507.863 500007.163 25.896 CNTRL 105 5455521.246 500027.803 25.939 CNTRL 107 5455523.987 500026.342 25.913 CNTRL 109 5455516.617 500026.349 25.917 CNTRL 113 5455509.853 500017.084 25.856 CNTRL 112 5455510.314 499997.972 25.862 CNTRL 117 5455512.127 500007.591 27.402 CNTRL 119 5455520.267 500023.428 26.496 CNTRL 115 5455532.161 499977.666 25.904 CNTRL 170 5455526.584 499988.118 25.874 CNTRL 125 5455515.774 499988.087 25.883 CNTRL 131 5455519.263 499989.753 26.677 CNTRL 123 5455538.733 500008.937 24.491 CNTRL 128 5455533.971 499998.893 25.326 CNTRL 130 5455531.750 500017.587 25.826 CNTRL 167 5455531.453 500006.740 26.945 CNTRL

Table 5.03 Total Station Survey Coordinates

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HDS Coordinate Results:

Instrument Setup Stations: (from Cyclone Registration) Pt. ID Northing (m) Easting (m) Elevation (m) Description 1001 5455508.078 500028.202 25.850 SE setup 1003 5455507.527 499986.776 25.879 SW setup 1005 5455533.464 499986.963 25.874 NW setup 1007 5455534.134 500027.215 25.854 NE setup Critical Exterior Building Points: (from Appendix G) Pt. ID Northing (m) Easting (m) Elevation (m) Description -‐ 5455512.041 500023.490 25.818 SE ground -‐ 5455512.062 499989.669 25.870 SW ground -‐ 5455531.463 499989.695 25.862 NW ground -‐ 5455531.438 500023.518 25.798 NE ground -‐ 5455512.009 500023.510 29.341 SE roof -‐ 5455512.043 499989.653 29.357 SW roof -‐ 5455531.470 499989.684 29.353 NW roof -‐ 5455531.455 500023.547 29.337 NE roof

Surrounding Control Points: (from Cyclone Registration) Pt. ID Northing (m) Easting (m) Elevation (m) Description 103 5455507.862 500007.163 25.889 CNTRL 105 5455521.246 500027.803 25.933 CNTRL 107 5455523.988 500026.341 25.909 CNTRL 109 5455516.617 500026.347 25.912 CNTRL 113 5455509.856 500017.083 25.853 CNTRL 112 5455510.316 499997.971 25.860 CNTRL 117 5455512.127 500007.591 27.400 CNTRL 119 5455520.267 500023.428 26.493 CNTRL 115 5455532.160 499977.667 25.901 CNTRL 170 5455526.584 499988.118 25.869 CNTRL 125 5455515.776 499988.089 25.879 CNTRL 131 5455519.263 499989.753 26.674 CNTRL 123 5455538.731 500008.936 24.482 CNTRL 128 5455533.970 499998.896 25.321 CNTRL 130 5455531.748 500017.587 25.823 CNTRL

Table 5.04 Laser Scanner Survey Coordinates

19

Coordinate Comparison Results: (HDS – T.S.)

Instrument Setup Stations: (from Cyclone Registration) Pt. ID Δ North. (m) Δ East. (m) Δ Elev (m)

1001 (SE setup) 0.000 0.002 0.030 1003 (SW setup) 0.000 0.002 0.000 1005 (NW setup) 0.000 0.001 0.016 1007 (NE setup) -‐0.001 -‐0.001 -‐0.002

Critical Exterior Building Points

Pt. ID Δ North. (m) Δ East. (m) Δ Elev (m) SE ground 0.008 0.004 -‐0.052 SW ground -‐0.001 -‐0.002 -‐0.016 NW ground 0.007 -‐0.002 0.009 NE ground 0.003 0.003 -‐0.038 SE roof -‐0.019 0.022 0.084 SW roof 0.001 -‐0.023 0.017 NW roof 0.006 -‐0.014 0.000 NE roof 0.005 0.032 0.015

Surrounding Control Points: Pt. ID Δ North. (m) Δ East. (m) Δ Elev (m) 103 -‐0.001 0.000 -‐0.007 105 0.000 -‐0.001 -‐0.006 107 0.001 -‐0.001 -‐0.004 109 0.000 -‐0.002 -‐0.005 113 0.003 -‐0.001 -‐0.004 112 0.002 -‐0.001 -‐0.002 117 0.000 0.000 -‐0.002 119 0.000 0.000 -‐0.003 115 -‐0.001 0.001 -‐0.003 170 0.000 0.000 -‐0.005 125 0.002 0.003 -‐0.004 131 0.000 0.000 -‐0.003 123 -‐0.001 -‐0.001 -‐0.009 128 -‐0.001 0.003 -‐0.005 130 -‐0.002 -‐0.001 -‐0.003

Table 5.05 Comparison of Laser Scanner and Total Station Coordinates

20

Levelling Results:

Instrument Setup Stations Pt. ID Elev. (m) Description 1 25.852 CNTRL 3 25.879 CNTRL 5 25.872 CNTRL 7 25.855 CNTRL

Surrounding Control Points

Pt. ID Elev. (m) Description 103 25.893 CNTRL 105 25.936 CNTRL 107 25.911 CNTRL 109 25.915 CNTRL 113 25.853 CNTRL 112 25.86 CNTRL 115 25.905 CNTRL 170 25.872 CNTRL 125 25.882 CNTRL 123 24.488 CNTRL 128 25.321 CNTRL 130 25.822 CNTRL


Pt. ID Elev. (m) Description SE GROUND 25.794 BLDG PT SW GROUND 25.83 BLDG PT NW GROUND 25.834 BLDG PT NE GROUND 25.794 BLDG PT SE ROOF 29.352 BLDG PT SW ROOF 29.369 BLDG PT NW ROOF 29.363 BLDG PT NE ROOF 29.345 BLDG PT Table 5.06 Levelling Elevations

21

Elevation Comparison: (Total Station results) – (Levelling results)

Instrument Setup Stations Pt. ID ΔElev.(m) Description 1 0.001 CNTRL 3 0.000 CNTRL 5 0.005 CNTRL 7 -‐0.001 CNTRL


Pt. ID ΔElev.(m) Description 103 0.003 CNTRL 105 0.003 CNTRL 107 0.002 CNTRL 109 0.002 CNTRL 113 0.003 CNTRL 112 0.002 CNTRL 115 -‐0.001 CNTRL 170 0.002 CNTRL 125 0.002 CNTRL 123 0.003 CNTRL 128 0.005 CNTRL 130 0.004 CNTRL


Pt. ID Elev. (m) Description SE GROUND 0.076 BLDG PT SW GROUND 0.056 BLDG PT NW GROUND 0.019 BLDG PT NE GROUND 0.042 BLDG PT SE ROOF -‐0.095 BLDG PT SW ROOF -‐0.029 BLDG PT NW ROOF -‐0.009 BLDG PT NE ROOF -‐0.023 BLDG PT

Table 5.07 Comparison of Total Station and Levelling Elevations.

22

Elevation Comparison: (HDS model elevations) -‐ (Levelling elevations)

Instrument Setup Stations Pt. ID ΔElev. (m) Description 1 -‐0.002 CNTRL 3 0.000 CNTRL 5 0.002 CNTRL 7 -‐0.001 CNTRL


Pt. ID ΔElev. (m) Description 103 -‐0.004 CNTRL 105 -‐0.003 CNTRL 107 -‐0.002 CNTRL 109 -‐0.003 CNTRL 113 -‐0.001 CNTRL 112 0.000 CNTRL 115 -‐0.004 CNTRL 170 -‐0.003 CNTRL 125 -‐0.002 CNTRL 123 -‐0.006 CNTRL 128 0.000 CNTRL 130 0.001 CNTRL


Pt. ID Elev. (m) Description SE GROUND 0.024 BLDG PT SW GROUND 0.040 BLDG PT NW GROUND 0.028 BLDG PT NE GROUND 0.004 BLDG PT SE ROOF -‐0.011 BLDG PT SW ROOF -‐0.012 BLDG PT NW ROOF -‐0.010 BLDG PT NE ROOF -‐0.008 BLDG PT

Table 5.08 Comparison of HDS and Levelling Elevations.

23

5.1 Accuracy Analysis

The analysis of results proved difficult since the building itself was measured almost

completely by reflectorless EDM. Table 5.06 displays the results obtained from conducting

an independent level loop. These elevation results will be considered “true” since the

levelling methods and instruments used yield far more accurate elevations than either total

station (2” vertical angle error + human error in measuring instrument/target heights) or

laser scanner methods (12” vertical angle error + human error in modeling procedures).

The level loop which was conducted had a misclosure error of 0.5 mm indicating an

accurate level run. The least squares adjustment results of the total station measurements

will be considered “true” for the horizontal coordinate comparison of the surrounding

control points because these are coordinated with a high level of confidence. The 95%

error ellipse data for control points is displayed in Table 5.09 below:

Pt ID Semi-‐Major Axis (m)

Semi-‐Minor Axis (m) NE-‐axis Azimuth 1 0.006 0.005 154° 53' 10" 3 0.008 0.006 175° 37' 23" 7 0.007 0.006 5° 06' 36" 5 0.009 0.007 20° 55' 15" 101 0.005 0.003 137° 09' 33" 103 0.008 0.007 93° 40' 59" 105 0.007 0.006 177° 25' 00" 107 0.009 0.006 178° 29' 49" 109 0.009 0.006 171° 17' 31" 113 0.008 0.007 100° 22' 36" 112 0.008 0.007 82° 07' 07" 117 0.008 0.007 94° 34' 28" 119 0.008 0.006 172° 00' 10" 115 0.010 0.008 19° 19' 07" 170 0.010 0.007 5° 26' 05" 125 0.010 0.007 4° 42' 02" 131 0.010 0.007 5° 58' 25" 123 0.009 0.008 84° 32' 22" 128 0.009 0.008 58° 08' 16" 130 0.009 0.007 65° 33' 41"

Table 5.09. Total Station Control Error Ellipses.

24

For the building corner horizontal coordinates, it is difficult to define which method

should be considered true. The precise pointing of the total station inspires some

confidence in its building corner coordinates, however, the frequent use of angle-‐offsets for

distances does not.

5.2 Point Analysis

The coordinate results in the above tables reveal several initial patterns. The first

was noticed in the field when residuals and standard deviation resection results with the

C10 scanner were greater than expected in the vertical plane. The levelling results

confirmed the resection’s vertical errors. After the 4 scanner point clouds were adjusted in

the registration process, the total station and scanner control point and instrument station

coordinates were in agreement. The other pattern was that both total station and HDS

building corner point coordinates did not agree with each other horizontally, but varied

more significantly in elevation. The levelling results showed that for both total station and

HDS methods, building corners at ground level were observed to be too high, and building

corners at roof level were observed to be too low. The analysis of these patterns is detailed

in the following paragraphs:

When conducting resections with the C10 scanner in the field, the resulting

standard deviations and residuals, shown in Table 5.10 indicated that the coordinate

results for setup points 1, 3, 5, and 7 were accurate as all standard deviations were sub

centimetre. Upon examination of the coordinate differences between the computed

resection results and the total station control results from Table 5.03, a discrepancy was

discovered in the elevation values. There is a notable elevation variance (>15 mm) which

occurs at three instrument setup locations (points 1, 3, and 5). The instrument set up at

point 1, indicates an elevation discrepancy of -‐32 mm. These elevation variations are

concerning especially considering that the horizontal coordinate differences vary only up

to a maximum of 4 mm in the Northings (point 3) and 2 mm in the Eastings (point 7). A

levelling check on the set up stations confirmed that the computed scanner resection

elevations were not accurate (errors up to 32 mm). The levelling of the instrument stations

yielded elevations close to those of the computed total station values (≤5mm) as shown in

Table 5.07.

25

Station Northing (m) Easting (m) Elev. (m) St. dev. N (m)

St. dev. E. (m)

St. dev. El. (m)

1001 5455508.078 500028.201 25.820 0.002 0.002 0.009

1003 5455507.527 499986.778 25.860 0.002 0.002 0.004 1005 5455533.464 499986.960 25.858 0.002 0.001 0.002 1007 5455534.135 500027.216 25.856 0.002 0.002 0.005

Table 5.10 Resection Results

After Cyclone registration, the total station control coordinates coincide very closely

with the HDS coordinates with an average error of 1mm in northing and easting and an

average error of 4mm and a maximum error of 9mm in elevation (see Table 5.03). The

difference between the Cyclone-‐registered control point elevations and the level loop

control point elevations was an average of 2mm and maximum of 6mm (see Table 5.08).

The largest elevation differences between total station and levelling elevations is +5mm,

(as indicated in Table 5.07) and reside in points 5 and 128 for the surrounding control

points. The post-‐registration laser scanner survey results agree with the levelling and total

station results, which were considered to be of higher accuracy.

The elevation values of building corners, however had a greater variation between

the scanner and total station results as seen in Table 5.05. The building points were

compared using the final Cyclone building model and the measured total station data.

There is a +84mm difference in elevation values in point coordinates for the SE roof corner.

The next largest discrepancy is -‐52 mm and resides in the SE ground corner. Ground points

would, typically, have more uncertainty as these points were defined by the intersection of

the building corner, which was formed by two wall planes, and the mesh ground surface,

which was decimated from hundreds of thousands of points down to only several

thousand. The elevation variations in the roof corners could be explained by the uneven

flashing on top of the roof being picked up by the scanner or possibly by the imprecise

instrument pointing of the operator when using the total station. The unique roof corners

are shown in Figure 5.11.

26

Figure 5.11 Typical Building Roof Corner in Reality and in Cyclone.

During the levelling check, it was discovered that any individual roof corner did not

vary more than 7 mm in elevation because of the flashing (see field notes in Appendix A).

Comparing the building corner elevations determined via levelling with the elevations

derived from total station measurements, as shown in Table 5.07, yield results as large as -‐

95 mm (SE roof corner). Comparing the level loop building elevations with the elevations

from the cyclone model have the largest variations in the SW ground corner (+40mm). The

average vertical error from the HDS roof corners was -‐10mm and the average ground point

error was +24mm. The average vertical error from the total station roof corners was -‐

39mm and the average ground point error was +48mm.

An interesting pattern is that all of the elevation errors at roof-‐level corners are

negative values and all elevation errors at ground-‐level corner points are positive values.

The vertical errors are of higher magnitude than expected and suggest possible blunders.

The directions of these errors are away from the building edges, where the EDM shot was

placed before turning the offset angles to the corner. If the horizontal angle offset was

applied, (and the horizontal building corner errors suggest that it was) and the vertical

angle offset was not, errors of this size and direction are probable. This however, is the risk

taken when so much importance is placed into a single shot and when operator errors can

occur during data collection instead of at the data processing stage.

27

Nevertheless, level loop elevation results indicate that the building points derived

from the Cyclone model are more accurate than those derived from total station

measurements. The scanner data is so dense (as seen in Figure 5.11), especially at the

building corners, that small imperfections are measured and can be modeled in the

software.

Horizontal building points more or less agree between the total station and laser

scanner results in Table 5.05. The discrepancies are all sub-‐centimetre at the ground-‐level

building corners with a maximum of 8mm. The most coordinate disagreement is found

again at the roof corners, but it is no more than 23mm. This can be explained by the

irregular flashing seen in Figure 5.11 interfering with the point cloud data and making it

difficult to measure a single point at the corner with the total station.

5.3 Surface Accuracy Analysis

Once planes were defined and statistics were accepted, millions of points were

uploaded and presented within the point cloud file. Different areas of the point cloud

contained certain amounts of noise. For instance, if a square is picked up by the scanner,

the scanner will pick up points that lie on the inside and on the outside of the true surface

of the square. This occurs for several reasons. First of all, there are unavoidable but minor

systematic and random errors in the point cloud coordinates. Varying amounts of noise

resulted in a difficulty in fitting modelled objects perfectly to the point cloud. Conducting a

region grow command to best fit surfaces to the model seemed to be the best way of fitting

surfaces to the point cloud. Considering the effects of noise, the final model of the building

is subject to minor errors in positioning.

In some cases, where objects were not as densely populated with points, the Cyclone

operator would have to make a ‘best guess’ as to where the true surface of an object begins

and ends. This was especially apparent in the modelling of more detailed and intricate

objects such as windows and doors. ‘Best guesses’ were made in a few areas where objects

were not scanned in an optimal geometry with regards to the placement of the scanner.

28

The fact that objects created in cyclone are mathematically uniform and parts of a building

are not, creates ambiguity. Cyclone’s mathematically generated surfaces might not

perfectly fit the true, imperfect building surfaces. This difference in surfaces must be

considered when using a model to obtain coordinate information and measurements. As

seen in Figure 5.12, there are small groups of points that did not fit the tolerances of the

defined surface. The irregularly shaped point clusters at (A), (B), and (C) appear to

represent the true building surface where the vertical lines at (D) are inaccurate since their

spacing suggests they were measured from the station on the far side.

Figure 5.12: Point Cloud Noise & Building Imperfections

Planar surfaces require a minimum of 3 points (Pi = xi, yi, zi) to be defined, all other

measurements add redundancy and increased confidence. The mathematical equation of a

3D plane is ax + by + cz = d, where a, b, and c are coefficients. An expression of a plane’s

orientation is the normal vector: This is the way a plane is defined in

Cyclone. The individual points from the total station survey are put into formulae (1) and

(2) seen in Figure 5.13 to derive similar plane equations (Keisan, 2014).

29

Figure 5.13 Plane Equation and Definition Formulae. (Source: Keisan, 2014)

The results for several planes selected from the total station 3D model are tabulated

in Table 5.14 which includes a, b, c, normal vector values, and point numbers of the points

that were used to define the planes (full points list in Digital Appendix H). The

corresponding planes from the Cyclone HDS model are listed in Table 5.15 which include

statistical information as well as a, b, c, and d values. A diagram of the selected plane

locations is found in Figure 5.16 and a plane comparison is found in Table 5.17.

Plane ID a b c Point #1 Point #2 Point #3 1 0.0303 12.5525 -‐0.0057 1042 1043 1044 2 -‐1.0161 0.0012 -‐0.0105 1030 1031 1032 3 0.0041 -‐2.8047 -‐0.0245 1146 1147 1148 4 0.0007 0.5188 -‐0.0003 1074 1075 1076

Table 5.14 Total Station Data: Plane Definition Parameters.

30

Plane ID a b c # of points St. dev. (m)

Max. abs. error (m)

1 0.0026 1.0000 0.0016 92,329 0.001 0.004 2 1.0000 -‐0.0009 -‐0.0015 52,370 0.002 0.004 3 0.0000 1.0000 0.0003 7,325 0.002 0.003 4 0.0008 1.0000 0.0030 3,147 0.002 0.004

Table 5.15 Cyclone HDS Plane Definition Parameters.

Figure 5.16 Sketch of Plane Locations.

Plane ID Angle between

vectors Pt.#1 Offset

(m) Pt.#2 Offset

(m) Pt.#3 Offset

(m)

1 0° 06’ 53” 0.0045 0.0001 -‐0.0004 2 -‐0° 39’ 51” 0.0030 0.0033 0.0000 3 -‐0° 29’ 32” 0.0016 -‐0.0025 0.0068 4 0° 13’ 45” -‐0.0038 -‐0.0039 -‐0.0028 Table 5.17 Comparison of Normal Vectors and Point-to-Plane Offsets.

The planes defined in Cyclone obviously have the most confidence and redundancy

given their statistics in Table 5.17. The Leica C10 also has less beam divergence than the

TPS802 total station. The beam divergence of the C10 (0.24 mrads) is at least half of the

TPS802 (min. 0.5mrads) (Leica Geosystems). For these reasons, the position and

orientation of planes defined by the C10 will be considered “true”. Defining a small plane

31

from 3 total station points however, has alignment issues. The planes defined by total

station do not agree with those calculated in Cyclone. Some points are offset by less than a

millimetre from their highly defined counterparts, but some are only offset by a few

millimetres. Figure 5.18 shows an example of a negative point-‐to-‐plane offset. Negative

offset values represent points on the near side of the Cyclone plane and positive values

represent points on the far side relative to the instrument station. Since there is no

redundancy in the plane defined by total station data, the plane is constrained to these

points and a noticeable rotational error is introduced.

Figure 5.18 Point to Plane Offset Screenshot.

5.4 Time Results & Analysis 5.4.1 Total Station Survey Time Results

Field time: 3h 33m

Office time:

Drafting: 6h50m @ full detail

Total: 10h 23m

32

5.4.2 Laser Scanner Survey Time Results

Field Time: Setting control with total station = 1h 02m (from field notes)

Field Time: Scanner data collection = 1h 37m (from field notes)

Office Time: 6h 17m

Total: 8h 56m (1h 27m faster)

5.4.3 Comments & Analysis

“Experience shows that the ratio of field to office working time of a scanning survey

is about 1:5. The office time can be reduced with the accumulation of the experience of

staff” (Chow, 2007). The laser scanner survey of NE28 had a ratio of 1:3.9 and the total

station survey was 1:1.9. Every project will yield different time results, “the field to office

processing time ratio increases with point density, complexity of the object(s) being

scanned, and deliverable detail” (California DoT, 2011). For this project, the laser scanner

method was 16% faster.

5.5 Analysis of Other Factors 5.5.1 Cost

The hardware and software listed in Table 5.19 are only the major purchases. Other

necessary equipment such as tripods, prism poles, computers etc. are not included in the

calculation since they are so common to all surveyors. Please note the following:

● *The Autodesk software is capable of point cloud modeling so the cost of Leica

Cyclone was not included in the total cost of the laser scanner survey.

● **The cost of the total station is included in the HDS column as it is required for

setting control points.

33

Equipment for Total Station Survey Equipment for HD Survey

Leica 2” total station $12,000 Leica C10 $100,000

AutoCAD Civil 3D $6,825 Leica Cyclone * $9,000

Leica HDS targets (2) $780

AutoCAD Civil 3D $6,825

Leica 2” total station ** $12,000

Total: $18,825 Total: $119,605

Table 5.19: Cost of Hardware and Software for Each Survey Type.

(Source: Keith Belsham pers. comm. March 17, 2014)

5.5.2 Data Volume

For this project the volume of data included in the total station survey was 2.87

megabytes which includes the fieldbook, least squares input/output files and the CAD

drawing file. For the laser scanner survey, the total volume of data was 284.63 megabytes

which includes the complete cyclone database project folder, and the exported Cad

drawing.

5.5.3 User-friendliness

Since the authors were already familiar with Leica total station and GPS programs,

the transition to HDS hardware was simple. The use of the C10 scanner hardware was

intuitive. The interface of the C10 scanner was the same as other Leica products like the

Viva controller. The traverse and resection procedures within the scanner hardware were

exactly the same as those presented in the Viva data collector. The most difficulty with the

hardware use arose when attempting to pick HDS targets from a touch screen with a live

digital camera display. It proved difficult to see a 6 inch HDS target from 90m away. It took

approximately six hours of scanner practice to become well versed with its interface. It can

34

be concluded that the Leica C10 scanstation scanner would prove simple to use for any

experienced total station user.

The authors were also familiar with CAD software, but Leica Cyclone 8.0.2 is not

similar. Navigation, registration, point selection, object creation and modification in

Cyclone are the main functions to learn and master. Considering the complexity of the

program and its many capabilities, the basic commands were not difficult to find and

operate. It took about twenty five hours, per person, of practice modelling to become

proficient with the basics of Cyclone software. In order to completely master Cyclone

commands and modelling procedures, more time would be needed.

35

6.0 CONCLUSION

Based on the results of dataset comparisons summarized in Table 6.1 below, and the

scope of the project, the laser scanner survey method is the more effective method.

Modern day scanning has the potential to become a powerful tool to Geomatics

professionals. HDS methods however, will not replace traditional survey instruments for

this type of project. Total stations are still required to set control points. Using a scanner

to set control proved to have limitations, mainly in the precision of short distance

measurements (<50m) that did not undergo registration.

Category HDS Traditional Field Time 2X quicker 2X Office Time Slightly faster Slightly slower

Control Point Accuracy Equal Equal Bldg Corner Accuracy Better Inferior

Planar Surface Accuracy Far Superior Inferior Cost 10x greater 10x less

Data Volume 10x greater 10x less User Friendliness Short learning curve Long learning curve

Tables 6.1 Summary of Results.

The accuracy of both survey methods were similar with regards to horizontal

control points and horizontal building corner coordinates. The HDS results however,

surpassed the total station’s when it came to the building corner elevations compared to

levelling results and also in the ability to define planar surfaces. The laser scanner method

was also more time efficient compared to the total station method.

Overall, human error was found to be more apparent in the conduction of the total

station survey. Taking many individual measurements with little to no redundancy

increases the risk of operator error which would require another trip to the project site.

Total station surveys require more detailed field notes, as all singular points need to be

identified. This spread of information requires the operator to interpret data uploaded

from the total station, as well as information recorded in field notes. This caused drafting

36

total station data to be more time consuming than was expected. Having to keep track of

points in the field when collecting data with a total station also proved to be subject to

human errors. In this particular survey, a small portion of the building was missed in the

collection of data with the total station. It can be concluded that these factors render total

station data collection to be more susceptible to human error than 3D scanner data

collection and drafting procedures.

The sheer amount of collected points in a single scan far outweighs any total station

capabilities (354 points vs. 6.4 million). This volume of data is a disadvantage in terms of

computer performance and modeling procedures. Modelling scanner data has the benefit

of all required information being present within the raw data files. This will reduce or

remove any requirements to return to the field to capture more data and is highly

advantageous for measuring inaccessible features.

Another issue surrounding modern day scanners is cost. As can be seen in the cost

analysis, figure 5.19, the required hardware and software to conduct an accurate scanner

survey is greater than $100,000. Comparing this to total station survey hardware and

software cost requirements yields a difference of approximately $80,000. If a particular

scan is to be linked to a specific control network, then the use of a total station or GPS

would be needed, as the C10 scanner is not practical for setting control. The user-‐

friendliness of the HDS systems used in this project were not unreasonably complicated for

those with knowledge of similar geomatics equipment.

Each survey method has its strengths and limitations and none are free of operator’s

errors. For this project the laser scanner method was the most efficient and effective.

Ideally, the most efficient survey-‐grade data collection method would be a combination of

the total station’s single-‐point precision, long-‐distance measurement to a prism, and

accurate orientation combined with the high level of detail and completeness of a laser

scanner. Recent innovations have begun to integrate several Geomatics technologies

including GPS. As technology advances, so does the ability to collect accurate, detailed,

time and cost effective spatial data.

37

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38

Leica Geosystems. Leica TPS 800 Series User Manual. Retrieved from:

http://www.surveyequipment.com/PDFs/TPS800_UserManual_en.pdf

Leica Geosystems. Leica ScanStation C10 Product Specifications. Retrieved from:

http://hds.leica-‐

geosystems.com/downloads123/hds/hds/ScanStation%20C10/brochures-‐

datasheet/Leica_ScanStation_C10_DS_en.pdf

Leica Geosystems. Leica ScanStation C10 p. 32. Retrieved from:

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&u

act=8&ved=0CCoQFjAA&url=http%3A%2F%2Fwww.gefos-‐

leica.cz%2Fftp%2FHDS_Laser_sken%2FPrezentace%2FLeica%2520ScanStation%2

520C10.ppt&ei=CYQwU7_mDMPTqgGNsoDYAw&usg=AFQjCNFssnVcKLpU_K2jqnJw

HRhA59FhzQ&sig2=rwxSkb2hbClJYMaKP4b4cw&bvm=bv.62922401,d.aWM

Leica Geosystems. Leica Sprinter Electronic Level. Retrieved from:

http://www.fltgeosystems.com/uploads/brochures/2574_1.pdf?1395552204

39

Appendices

Appendix A: Field Notes

46

Appendix B: Least Squares Analysis Output File (condensed)

*NOTE: Linear distances are imperial values and were scaled to metric for the Report*

SURVEY LEAST SQUARES CALCULATION Tue May 28 14:11:32 2013 Project: WOES_Proj Input File: U:\WILL\SCHOOL\PROJECT\WOES_PROJ\PROJECT\NETWORK_IN.LSI Total # of Unknown Points: 20 Total # of Points : 22 Total # of Observations : 259 Degrees of Freedom : 199 Confidence Level : 95% Number of Iterations : 3 Chi Square Value : 226.29122 Goodness of Fit Test : Passes at the 5% Level Standard Deviation of Unit Weight: 1.06637

************************************************************************

OBSERVATIONS ************************************************************************

(For full list of observations see Digital Appendix I)

************************************************************************ ADJUSTED COORDINATES

************************************************************************

Point Northing Easting Elevation ______ _____________ _____________ ____________

1 17898648.5508 1640512.4754 84.8179 3 17898646.7412 1640376.5558 84.9042 7 17898734.0333 1640509.2365 84.8242 5 17898731.8326 1640377.1736 84.8988 101 17898628.1304 1640816.0522 78.8555 103 17898647.8438 1640443.4477 84.9596 105 17898691.7514 1640511.1658 85.1019 107 17898700.7457 1640506.3724 85.0166 111 17898676.5658 1640506.3945 85.0297 113 17898654.3736 1640475.9971 84.8306 115 17898655.8857 1640413.2938 84.8483 117 17898661.8326 1640444.8536 89.9009 119 17898688.5399 1640496.8098 86.9278 125 17898727.5621 1640346.6739 84.9867 127 17898709.2637 1640380.9638 84.8881 129 17898673.7996 1640380.8617 84.9193 131 17898685.2449 1640386.3280 87.5218 141 17898749.1227 1640449.2698 80.3507

47

147 17898733.5006 1640416.3161 83.0905 149 17898726.2134 1640477.6488 84.7297

************************************************************************

Standard Deviations -‐ Adjusted Coordinates ************************************************************************

STANDARD DEVIATIONS Point North East Elevation ______ ____________ ___________ ___________ 1 0.007085 0.006469 0.002873 3 0.009870 0.007907 0.003338 7 0.008438 0.007412 0.003243 5 0.010751 0.008619 0.003511 101 0.005613 0.005449 0.003712 103 0.008754 0.010535 0.003808 105 0.009148 0.007110 0.003418 107 0.010819 0.007546 0.003852 111 0.010686 0.007475 0.003894 113 0.008293 0.010343 0.003804 115 0.009288 0.010283 0.003810 117 0.008777 0.010088 0.012462 119 0.010004 0.007601 0.008553 125 0.012006 0.010270 0.004064 127 0.012610 0.008816 0.004047 129 0.012592 0.008613 0.004046 131 0.012156 0.008684 0.010625 141 0.009979 0.010971 0.011574 147 0.010495 0.011096 0.005872 149 0.009498 0.010810 0.004017

************************************************************************

Least Squares Error Ellipses at 95% Confidence Level

************************************************************************

Point Semi-‐Major Axis Semi-‐Minor Axis NE-‐Axis Azimuth ______ _______________ _______________ _______________

1 0.0191566630 0.0166044236 154-‐53-‐10 3 0.0261071790 0.0208589819 175-‐37-‐23 7 0.0223159885 0.0195605611 5-‐06-‐36 5 0.0292640266 0.0216643001 20-‐55-‐15

101 0.0172660235 0.0113636601 137-‐09-‐33 103 0.0278541002 0.0231089172 93-‐40-‐59 105 0.0241843268 0.0187750660 177-‐25-‐00 107 0.0285925151 0.0199322464 178-‐29-‐49 111 0.0284066724 0.0195035693 171-‐17-‐31 113 0.0274972823 0.0217014687 100-‐22-‐36 115 0.0272197572 0.0244891088 82-‐07-‐07 117 0.0266770966 0.0231659090 94-‐34-‐28 119 0.0265457678 0.0199372022 172-‐00-‐10

48

125 0.0323143244 0.0264293063 19-‐19-‐07 127 0.0333996456 0.0231832543 5-‐26-‐05 129 0.0333327423 0.0226703285 4-‐42-‐02 131 0.0322052967 0.0228239584 5-‐58-‐25 141 0.0290137585 0.0263425798 84-‐32-‐22 147 0.0302750108 0.0266845303 58-‐08-‐16 149 0.0293978333 0.0241124677 65-‐33-‐41

************************************************************************

Least Squares Error Ellipses STANDARD ERROR ELLIPSES

************************************************************************

Point Semi-‐Major Axis Semi-‐Minor Axis NE-‐Axis Azimuth ______ _______________ _______________ _______________

1 0.0077310000 0.0067010000 154-‐53-‐10 3 0.0105360000 0.0084180000 175-‐37-‐23 7 0.0090060000 0.0078940000 5-‐06-‐36 5 0.0118100000 0.0087430000 20-‐55-‐15

101 0.0069680000 0.0045860000 137-‐09-‐33 103 0.0112410000 0.0093260000 93-‐40-‐59 105 0.0097600000 0.0075770000 177-‐25-‐00 107 0.0115390000 0.0080440000 178-‐29-‐49 111 0.0114640000 0.0078710000 171-‐17-‐31 113 0.0110970000 0.0087580000 100-‐22-‐36 115 0.0109850000 0.0098830000 82-‐07-‐07 117 0.0107660000 0.0093490000 94-‐34-‐28 119 0.0107130000 0.0080460000 172-‐00-‐10 125 0.0130410000 0.0106660000 19-‐19-‐07 127 0.0134790000 0.0093560000 5-‐26-‐05 129 0.0134520000 0.0091490000 4-‐42-‐02 131 0.0129970000 0.0092110000 5-‐58-‐25 141 0.0117090000 0.0106310000 84-‐32-‐22 147 0.0122180000 0.0107690000 58-‐08-‐16 149 0.0118640000 0.0097310000 65-‐33-‐41

************************************************************************

Blunder Detection/Analysis ************************************************************************

(For full list of observations see Digital Appendix I)

49

Appendix C: Cyclone Registration Results Status: VALID Registration Mean Absolute Error: for Enabled Constraints = 0.005 m for Disabled Constraints = 0.000 m Date: 2014.02.21 14:34:10 Database name : Proj_jan4 ScanWorlds Cyclone_Control.txt (Leveled) 1001: SW-‐001 (Leveled) 1003: SW-‐004 (Leveled) 1005: SW-‐003 (Leveled) 1007: SW-‐002 (Leveled) Constraints

Name ScanWorld Weight Error Error Vector (X) Error Vector (Y) Error Vector (Z) 103 SW-‐001 1.0000 0.004 0.003 -‐0.002 -‐0.001 103 SW-‐004 1.0000 0.005 -‐0.002 -‐0.003 -‐0.004 105 SW-‐001 1.0000 0.002 -‐0.001 -‐0.002 0.001 105 SW-‐002 1.0000 0.004 0.000 0.000 -‐0.004 115 SW-‐004 1.0000 0.003 0.002 -‐0.002 -‐0.001 115 SW-‐003 1.0000 0.002 0.000 -‐0.001 0.001 125 SW-‐004 1.0000 0.004 0.004 0.001 0.001 125 SW-‐003 1.0000 0.005 0.004 0.004 0.000 123 SW-‐003 1.0000 0.008 -‐0.004 -‐0.002 -‐0.006 123 SW-‐002 1.0000 0.005 0.000 -‐0.002 -‐0.005 128 SW-‐003 1.0000 0.006 0.005 -‐0.002 0.003 128 SW-‐002 1.0000 0.005 0.005 -‐0.001 0.001 107 SW-‐001 1.0000 0.002 0.000 0.001 -‐0.002 107 SW-‐002 1.0000 0.005 -‐0.004 0.003 0.003 109 SW-‐001 1.0000 0.005 -‐0.005 0.001 -‐0.001 113 SW-‐001 1.0000 0.005 -‐0.003 0.004 0.001 113 SW-‐004 1.0000 0.005 -‐0.001 0.004 0.003 112 SW-‐004 1.0000 0.006 -‐0.002 0.004 0.004

50

ScanWorld Transformations Cyclone_Control.txt (Leveled) translation: (0.000, 0.000, 0.000) m rotation: (0.0000, 1.0000, 0.0000):0.000 deg 1001: SW-‐001 (Leveled) translation: (500028.200, 5455508.078, 27.545) m rotation: (0.0000, 0.0000, 1.0000):-‐93.799 deg 1003: SW-‐004 (Leveled) translation: (499986.777, 5455507.527, 27.596) m rotation: (-‐0.0000, -‐0.0000, -‐1.0000):90.491 deg 1005: SW-‐003 (Leveled) translation: (499986.962, 5455533.464, 27.614) m rotation: (-‐0.0000, -‐0.0000, -‐1.0000):11.003 deg 1007: SW-‐002 (Leveled) translation: (500027.215, 5455534.134, 27.559) m rotation: (0.0000, 0.0000, 1.0000):-‐98.354 deg Unused ControlSpace Objects Cyclone_Control.txt (Leveled): Vertex : TargetID : 1001 Vertex : TargetID : 1003 Vertex : TargetID : 1005 Vertex : TargetID : 1007 Vertex : TargetID : 101 Vertex : TargetID : 170 1001: SW-‐001 (Leveled): Vertex : unlabeled 1003: SW-‐004 (Leveled): Vertex : unlabeled 1005: SW-‐003 (Leveled): Vertex : unlabeled 1007: SW-‐002 (Leveled): Vertex : unlabeled

51

DIGITAL APPENDICES

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