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User Project Presentations
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Quality control for land base and facilities conversion
Lessons Learned
- A significant investment of time must be expended in the quality control process. Time estimates
used for planning quality control activities are (per map sheet):
| Digital Orthophoto Check Plot |
-30 minutes |
| Planimetric Check Plot |
-90 minutes |
| Topo Check Plot |
-30 minutes |
| Water System Check Plot |
-180 minutes |
| Sewer System Check Plot |
-180 minutes |
| Planimetric, Topographic, and Digital Orthophoto Digital QC |
-90 minutes |
| Water System Digital QC |
-120 minutes |
| Sewer System Digital QC |
-120 minutes |
- There area variety of options that an organization can consider when planning the logistics of
conducting quality control during a large data conversion project:
Contract out all quality control work
Complete in-house quality control
Split QC responsibility with a contractor
Contract out QC management, QC staff training, and QC application development
The choice depends on the amount of money that can be spent on such an endeavor and the
flexibility an organization has in terms of hiring. The more QC there is conducted in-house the less
expensive the QC will be, but there will be requirements for hiring a QC manager or assigning those
duties to an existing employee. The QC duties will take the QC manager away from most other work
until the period of data conversion is over (anywhere from 1 to 3 years or more). QC technicians
will also need to be hired. It is suggested that there be significant in-house GIS expertise if complete
in-house QC review is planned by an organization.
The other options are varying degrees of using contractors. If the organization feels it can provide
technical staff, but needs expertise, contracting out QC management, training and application
development can be effective. Splitting QC responsibility with a contractor is appropriate when an
organization feels it can only commit portions of their staff members time. Finally contracting out
all QC work, can be effective when an organization has restrictions on hiring and does not have the
existing personnel to carry out the necessary steps.
- Development of a database design is extremely important and should be understood by both the QC
reviewers and the conversion contractor. An initial pilot project should be conducted that tests the
adequacy of the database design. The pilot project should result in a database design that has been
updated to reflect all changes necessary to accommodate unforeseen circumstances. Also, a formal
procedure should be developed for proposing and accepting changes to the database design during
the compilation and conversion process.
- A large data conversion project results in the generation of a great quantity of hard copy plots that
need to be kept in an organized fashion. When planning for quality control, provisions must be
made for storing plots in a manner that allows el%cient retrieval by delivery group and status. Often
there will be check plot deliveries for a delivery group during the same time period that the
contractor is submitting confirmation plots with accompanying check plots from a previous delivery
group. It is important for the sake of efficiency to be able to store them all separately.
Several methods for tracking quality control must be implemented. A digital quality control
application that color codes map sheet tiles according to the acceptance status, scheduled delivery
date, delivery group, and staff member assignment is extremely helpfid. This provides a quick way
to generate graphic status reports. Other aspects of quality control tracking involve developing
transmittal sheets, and a quality control log.
Conclusions
Data conversion is a complex task and requires careful planning and management. A comprehensive
workpkm should be developed which outlines what features are to be captured, how they are to be
captured and represented and coded, and what attributes are to be recorded. A pilot project can resolve
these problems early in the conversion effort and can serve as a guideline for a full scale conversion
process. A mechanism for maintaining communication between the contractor and client for
identification of any anomalies in the source materials, situations not taken into account by written
specifications, or errors in data conversion throughout the conversion process should be developed.
Once a problem is identified, the contractor and the client should work together to resolve the problem.
The accepted resolution should then be used to modifi the workplan for the data conversion.
QC should not be thought of as merely “catching contractor mistakes”. While the primary purpose of
carrying out QC procedures is to identifi and correct errors in delivered products, the QC process serves
many fimctions:
- Quality control insures that the digital database is complete in its content of graphic features and
associated attributes.
- Quality control familiarized users at the Commission with their digital database and its uses.
Carrying out quality control procedures provides an opportunity to identi~ anomalies in source
documents and to correct them.
- Digital quality control familiarizes users at the Commission with their GIS software and its
capabilities.
- Quality control develops a level of confidence in the digital database among users at the
Commission.
Boston Water and Sewer Commission Land Base Conversion Quality Control Process
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