Standards and Guidelines

This section can be used as a stand-alone reference to aid users of Global Positioning Technology (GPS) in gaining a better
understanding of the technology and to improve the quality and accuracy of the data they acquire. It also provides the
foundation for Section B - Data Accuracy Standards and Section C - Content Specifications that are geared to support
project where GPS data is acquired through contractual agreements.

This paper outlines the steps required to convert ARC/INFO coverages
from the North American Datum of 1927 (NAD27) to the more
accurate North American Datum of 1983 (NAD83).

Data maintenance is often an expensive yet neglected aspect of
managing GIS data. Each data layer is unique and will have its own
system for making and tracking updates. By consequence, tools for
data maintenance are generally not built into GIS software.
This guideline contains a collection of techniques and procedures for
managing GIS data layer updates. Appropriate techniques can be
adopted (with modification as need be) for a given data layer. Some
data layers change very little over time, and may only require simple
procedures for reporting errors and making rare revisions. Other layers
change often and require procedures for recording updates in a manner
that supports quality control and tracking of changes over time. A full
range of techniques is discussed here, including methods which enable
an audit trail of modifications over time for a given feature. The text is
primarily intended for those familiar with the Arc/Info GIS software.

This guideline provides local communities with guidance in
developing a project and project goals, preparing a request for
proposals (RFP), and executing a contract for GIS mapping or
analytical services. Included are technical and administrative
specifications that are important to ensure the creation of a quality
community product useful for many years to come.

This document is primarily for ARC/Info system managers and
technicians. The directory and file naming conventions recommended here are used
by VCGI. Communications with VGIS sites and user support will be
simplified if these conventions are followed. Also, any applications,
software or SMLs/AMLs developed by VCGI will use these
conventions. Most importantly, if these conventions are followed, this
document can serve as part of your system documentation for future
users at your site.

GIS attributes contain information associated with geographic features
on a map. GIS users, present and future, will most likely need to
develop attribute tables for new layers of map information. Existing
attribute tables will need to be expanded as well. The Vermont Center
for Geographic Information, Inc. (VCGI) encourages Vermont users of
geographic information to use the same base attributes and codes so
that data can be more easily exchanged and understood by all users.

The Vermont Future Land Use GIS Data Standard seeks to: 1. define a data framework for using GIS to map regional future land use plans.
2. Define a data framework that supports easy identification of: a) RPC to which a data set pertains.
b) adoption date of plan that the data set models.
3. Provide the data framework as a resource that can be extended to meet local-regional business needs.

The objective is to provide a source document for any organization or
political body wishing to regulate the use of the Vermont Coordinate
System, and as such, the impact of these standards is dependent on the
actions of those outside institutions. The reasons for utilizing the
Vermont (state plane) Coordinate System are:
1. To describe on a common datum, the position of points on,
above, or under the surface of the earth.
2. To perpetuate said positions in a convenient format.
3. To standardize the location of objects, points, and other
entities, as recorded in geographic/ land information systems,
(G/LIS) and other spatially related databases, for use in analytic
and mapping applications.
4. To facilitate future survey retracement of land boundaries.

This guideline will identify aspects of the parcel mapping process, issues to consider, and provide template documents that will assist listers, assessors, and other town officials with their duties as they relate to the development of parcel maps and data. An overview of the process is provided before the template documents. Please refer to the current VT GIS Parcel Data Standard at the VCGI web site (vcgi.vermont.gov) for technical specifications relevant to the creation or update of the parcel data used to create maps.