The Data Capture Challenge - Innovative Solutions
Philip Pickford
New Zealand Aerial Mapping Limited PO BOX322 Albany
Auckland New Zealand
Abstract
This paper focuses on innovative in-field data capture techniques that have solved real
problems facing utilities. These techniques have been developed and refined by way
of experience gained in a number of large scale data capture projects. Utilities
considering data capture projects face numerous challenges, including scope,
methodology, cost and quality control. These challenges are discussed, along with
options available which conform to a number of practical and user-defined principles.
Global positioning systems (GPS), gee-referenced imagery and data entry are
discussed, as they pertain to in-field capture, with an emphasis on using this
technology in different and innovative ways. The paper uses a case study to expand on
the principles and options discussed. The project cited is the largest data capture
project undertaken in New Zealand and involves positioning and attribute capture of
over 100,000 power poles. This project has been especially challenging because of
factors such as difficult and remote terrain, tight budgetary constraints and very
challenging timelines. Data capture for this particular project is discussed, covering
methodology, digital topographic landbase use, digital gee-referenced imagery
capture and quality control procedures.
Principles of Data Capture
Data capture is best defined as the means by which information relating to physical
entities (the data) is transferred into a digital format. This transfer can either originate
from plans where the information contained in the plans is converted directly into a
digital form with no additions (data conversion), or where the plans are used simply as
a guide to in-field data capture where the information is gathered as a result of direct
observation of the particular physical entity (field inventory).
Invariably, data conversion involves the digitizing or scanning of existing plans
producing a digital copy of those plans. Using this method there is little opportunity to
improve or add to the data. Any errors, inaccuracies or shortcomings in the existing
plan data will be reflected in the converted digital data. Using this method of data
capture is therefore very dependent on the quality and completeness of the existing
plan information.
Field inventory involves visiting the plant on-site and using that visit to observe the
attributes that need to be captured. Existing plans can be used as a guide, however, the
actual data captured is directly related to on-site observations. This data needs to be
input on-site as well, ensuring real-time observation and input. This method allows for
extensive attribution; anything that can be observed and confirmed can be captured. It
also gives the opportunity for considerable data improvement, both in terms of
accuracy and completeness. This paper focuses on field inventory as a practical and
cost effective data capture methodology.
When discussing data capture principles, two perspectives must be reviewed: the
perspective of the organisation that will ultimately use the data (The Client), and the
organisation that will physically capture the data (The Contractor). For a successfid
data capture project these two perspectives must align and be complementary, thus
allowing for clienticontractor partnerships to develop rather than the more traditional
situation of argument and conflict.
The Client
The foremost principle fi-om the client’s perspective is to ensure that clear and well
defined objectives are in place that will ensure the key business drivers for automated
mapping, facilities management, geographic information systems (AM/FM./GIS)
within the organisation are satisfied. These objectives will in turn dictate the
information required, the appropriate methodology and quality standards of the data
captured and the acceptable cost parameters.
The Contractor
Of prime importance to a contractor is to ensure he completes the data capture
contract to the satisfaction of the client. In order to facilitate this result he must ensure
he is fully aware of the clients specific requirements and the data capture
methodology he uses must be able to meet those specific requirements within the cost
constraints imposed by the client. The response to this simple challenge is the
difference between a successfid project and a failed project, and can best be
enlightened by fostering a close and productive client/contractor relationship. The
contractor must work within his own constraints to ensure successful completion.
These fundamental constraints are the product of experience and detailed analysis:
Single Site Visit
Visit the site once to capture data. Ensure that all data is captured and all tasks are
completed at that single visit. In short - “the do it once, do it right principle”.
Data Entry
Methods of data entry must ensure a balance of three factors - speed, accuracy and
cost. Data entry must be on-site to ensure the closest correlation between on-site
observation and data entered.
Digital Landbases
An integral part of field inventory is the use of digital landbases. The use of a
photogrammetrically derived digital landbase of physical features with a defined and
absolute spatial accuracy level allows on-site confidence of real-time GPS with the
opportunity of absolute gee-referencing of plant. As a result all positional quality
assurance is real-time and on-site.
Quality Assurance
On-site quality assurance must be maximised, allowing the principle of “do it once, do
it right” to be confirmed. However, a method of off-site quality assurance must also
be possible. This area has been of considerable challenge but technology has been
able to provide solutions, primarily in the area of gee-referenced digital imagery.
