DT9419/20 - Dublin City Council Spatial Data Capture Methodology

This report details a spatial data capture and delivery methodology for Dublin City Council (DCC) regarding their on-street assets. It proposes an optimal approach from data collection to data delivery, focusing on creating a georeferenced spatial database. The report is divided into three main sections: data collection methods, the georeferencing process, and data quality maintenance. The data collection section emphasizes accurate data capture using GPS and other techniques, while the georeferencing section discusses database setup, user interfaces, and georeferencing procedures. The data quality maintenance section covers feedback mechanisms, data cleaning, validation, and correction processes to ensure the reliability of the spatial data. This methodology aims to provide DCC with a robust framework for managing and utilizing their street asset data effectively. Desklib provides access to a wealth of study resources, including similar reports and past papers, to aid students in their academic pursuits.

Dublin City Council Spatial Data Capture
and Delivery Methodology.
Name:
Course Code: DT9419/20
Module: SSPL9043
Year of Course: 2018-2019
Staff: Dr. Audrey Martin /. Dr Eugene McGovern

Abstract
This report is about Dublin City Council, which wants to create a geo-referenced spatial database
for their street assets. The report explains the optimal methodologies that the Georeferencing
team should take to capture that data and record it, store it in the database, use it for
Georeferencing and finally maintain the quality of the data.
The report has three parts:
 Data collection methods
 Geo referencing process
 Data Quality maintenance
The first part explains in detail how the team should collect accurate data, using optimum
methods and techniques.
The second part deals with how the team should use the data for geo referencing.
The third part is about the techniques of data maintenance and validation, as well as data quality.
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Table of contents
Chapter 1: Asset Data Collection...................................................................................................5
1.1 Why good recording?........................................................................................................5
1.2 Recording of localities......................................................................................................5
1.3 Coordinate recording.........................................................................................................6
1.4 Global Positioning System................................................................................................7
1.5 Elevation recording...........................................................................................................7
1.6 Recording the size of the area...........................................................................................8
1.7 Collection year..................................................................................................................8
1.8 Documentation..................................................................................................................8
Chapter 2: The Georeferencing process..........................................................................................9
2.1 Tools and resources...............................................................................................................9
2.2 Setting up the database..........................................................................................................9
2.2.1 Locality description fields.......................................................................................10
2.2.2 Fields associated with Georeferencing.........................................................................11
2.2.3 Handling ecological data..............................................................................................13
2.2.4 Database constraints.....................................................................................................13
2.3 User Interfaces for Georeferences.......................................................................................13
2.4 Standards and guidelines.....................................................................................................14
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2.5 Georeferencing procedure...................................................................................................15
Chapter 3: Data Quality Maintenance...........................................................................................16
3.1 Feedback to the data collection team...................................................................................16
3.2 User feedback......................................................................................................................16
3.3 Cleaning and Checking of data............................................................................................17
3.3.1 Data entry......................................................................................................................17
3.3.2 Data validation..............................................................................................................17
3.3.3 Correcting.....................................................................................................................18
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Introduction
Georeferencing is the process of relating the coordinates of a map to real objects on the earth’s
surface. There are various techniques to geo reference. This report includes the optimum
methods that enhance geo referencing. Any kind of specimen can be geo referenced as long as it
can be associated with a map.
This report specifically covers the methods that the Dublin City Council team can implement in
the city to locate their required assets. The extent of data collection in this case will be the
Dublin City.
The report suggests the optimum methods that the DCC team can adopt to get accurate and
explicit results. Data collection, geo referencing and data maintenance are explained in details in
the chapters that follow
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Chapter 1: Asset Data Collection
Georeferencing can be a hard task. Therefore, good methods of data collection in the field are
essential as they form the back bone of Georeferencing. Nowadays, many efficient and accurate
data collection techniques are there to facilitate the process. However, recording the locations
correctly reduces errors. Since using a Global Positioning system (GPS) is more accurate and
efficient, the Dublin City council (DCC) data collection team should use it.
1.1 Why good recording?
Describing locality well yields more reliable georeferences with minimum levels of uncertainty,
Huang, B. (2018). This outputs data that has a high quality. Recording locality information is
essential, whether one is using a map or GPS, to make data validation easier.
Validating coordinates is one way of good locality description. Spatial and locality description
play an important role in the accuracy of data. They determine how reliable the recorded data is.
For example, using a small reference point increases the data accuracy. Choosing a reference
point that is nearby also reduces errors in offset data measurements, Farkas, G. (2017). The DCC
should use reference points that are easily findable on maps. If a locality has two places with
names that can cause confusion, add the feature type alongside the name of the feature. For
example;
1.2 Recording of localities
The team should ensure that the localities are highly described, even when they are using
geographic coordinates. To avoid possible uncertainty, each locality should be clear, unbroken,
specific and accurate, Pehcevski, J. (2018). Localities that describe reference points should be
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such that they are permanent, that is, they will remain for a long time even after completing data
collection. Such localities include towns and trigonometry points, DeMers, M. (2017). The DCC
team should avoid using temporary locations as reference points. For example, assume then you
have made accurate GPS recordings but used a temporary reference point as your key reference
point, referencing future points from that point, for example ‘600 meters from the lorry’. This
may be useful during data collection but useless in future, because knowing where the lorry was
at that time of recording is not easy. If the team will record locations that follow a path, for
example road or a river, they should record the method they used to measure, that is, by road or
by air.
1.3 Coordinate recording
Geographical Information systems readily use coordinates to function, Sang, N. (2018).
Coordinates offer a convenient way to describe a locality exactly. They are more detailed and
highly accurate than normal locality description. Including as many decimals as possible in
coordinates increases the precision, Tiwari, A. & Jain, K. (2017). The team should focus on
measuring the coordinates using the decimal system and include as many decimal places as
possible. For example, recording a coordinate with 6 decimal places is more accurate than using
3 decimal places, as well as using degrees, minutes and seconds in coordinate description. The
team should also consider using GPS receivers as they now offer the coordinate positioning in
decimal form, and this is more precise than the degree system. When the team collects
information in a certain location, they should consider recording the exact location where they
have collected data, where practical. If they read the coordinates directly from a map, they
should follow the map’s coordinate system Campelo, et al. (2017). This decimal degrees method
only describes coordinates on terms of longitudes and latitudes, hence it is more accurate and
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flexible, and can be transformed to other coordinate systems as needed, Pehcevski, J. (2018). The
DCC team should record all coordinates of their assets using the decimal system. Where
practical.
1.4 Global Positioning System
By using triangulation, the Global Positioning system determines the location a feature on the
surface of the earth, Srivistava, G. (2014). It is a technology that calculates the distance by
finding the distance between two components; the GPS receiver and the satellites. The positions
of the GPS satellites are on known places on the earth, making calculations for other positions on
the earth easier by using the satellites as the reference points. Evaluating the location of a feature
on the earth’s surface requires at least four GPS Satellites, Bui, D. (2018).
To ensure that the GPS receivers work well, the DCC team should place them strategically, away
from reflective surfaces. They should not be places near obstructions that can prevent them from
communicating with the satellites well. There should be a clear field of view to the horizon.
The local conditions at the time of recording determines the accuracy of the GPS, Wise, S.
(2013). For example, GPS errors may increase as the size of the locality increases. To solve this,
the team should calculate the average of the GPS values obtained after recording the values on
various attempts at the same location.
The team should also consider using Differential GPS, as it is more accurate than the normal
GPS. It refers to a known GPS base station and calculates the position, Panigrahi, N. (2014).
This reduces errors such as atmospheric conditions, as both the receiver and the base station
references the satellites at the same time. The handheld GPS in this case, will correct any
discrepancies.
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1.5 Elevation recording
The elevation information is essential in geo referencing. The team should measure the elevation
to add onto locality description.
The team should use barometric altimeters to measure elevation if possible, Grueau et al. (2017)
They can also use laboratory-based methods like Digital Elevation Model. Using maps is also
possible by finding contours and height information from a well scaled map. GPS devices do not
measure accurate elevations most of the time. This is because a GPS’ height is not usually the
actual height (Stefanakis, E. 2014). It is the height of the object, relating to a model of the
surface of the earth.
1.6 Recording the size of the area
The size of the locality means the distance from one locality recording to the furthest point that is
included in the recording. Recording the size of the area should be a priority to the data
collection team as that makes the user gain more insight and make use of the recorded data.
Size recording is important when the activities have occurred over a minimal range or area.
The team should describe the area covered by a single locality as a whole, for example, 3
kilometers of the area. This offers the user with a way of specifically determining the locality
(DeMers, M. 2017). Where possible, they should provide a map to supplement the recording.
1.7 Collection year
The data collection year is useful in many ways. It affects geo referencing of a location. This is
because location names can change over time, like towns, even boundaries. Some physical
features can change too, like meanders and oxbow lakes, rivers can change paths, new volcanic
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eruption can occur, sizes and shapes of locations can change and new maps may not represent
such information. The DCC team should explicitly state the date of collection in their recordings.
1.8 Documentation
The team should record all the tools used and the sources of their measurements, Favorskai︠a︡, M.
& Jain, L. (2017). Some of the components of the documentation should be a well labelled and
scaled map, the model of the GPS, the elevation’s source of data and the size of the area they
were recording.
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Chapter 2: The Georeferencing process
This is where the team associates the coordinate system with actual assets on the ground. The
team has to consider several issues before the geo referencing process. This can be a hard task
but it they can simplify it by using various techniques. One needs to have a knowledge of tools to
be use and the pros and cons of Georeferencing a collection (Majumder, M. 2018). The team
needs knowledge of the database management system. User interface if the database should be
appealing and make it easy to use the database. Several data entry options exist, including direct
entry of data into the computer, scans and photograph capturing tools that aid in bringing the
information to the screen. The data entry specialist can also use their handwriting to input the
data I the computer using OCR tools, Choudhury et al (2009).The team should make a decision
on the data entry method that they are going to use.
2.1 Tools and resources
The following are the basic tools that will be required.
 A database and A DBMS software. The team should not use spreadsheets.
 Maps. The maps used should be topographic, in electronic form or paper form.
 Internet access. This may help in locating resources and already Geo-referenced.
Good computer hardware.
2.2 Setting up the database
An important factor in Georeferencing is getting the database right the first time. This reduces
problems that may occur later. Sometimes the use of a separate database for data entry may be
essential so that the working data is different from the final data. This makes the data that has
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already been worked on not to be hindered or destroyed. The team can upload the working data
to the main data after it they prove its accuracy.
The team should determine beforehand what fields to include in the database. The correct fields
should be included in the model. The team should consult first before the actual Georeferencing.
The data entry team should not place all the similar data into one field, Jensen, J. & Jensen, R.
(2013)
The data should be atomized into as many different fields as possible, to enhance sorting and
searching. For example, when collecting longitudes and latitudes data, the team should create
two separate fields to represent the data, Gorr, W. & Kurland, K. (2017). The other necessity in
databases is choosing which fields will be visible to the data entry team doing data entry. Some
types of data are important when geo referencing, for example the collection date, the ID number
of each specimen, and their taxonomy.
2.2.1 Locality description fields
Georeferencing information should be stored wisely in a database. The main challenge is
choosing how to store localities. The team should divide the geo referencing into two parts; the
fields associated with locality description and other fields described below.
The fields describing the locality can be further broken down into the individual components
such as:
 Name of the location
 The actual distance and the direction of the locality
This information should be included in separate fields of the database.
Other fields include:
 The date of last modifications
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