Managing Records: Electronic Records: Managing GIS Records: GIS Development Guides
GIS Development Guides
Needs Assessment
- Introduction
- Conducting a Needs Assessment
- Local Government Uses of GIS
- Data Used by Local Government
- Documenting GIS Needs
- Documenting an Activity-Type Use of the GIS
- Master Data List
- Conducting Interviews
- Preparing the Needs Assessment Report
- Summary
- Appendix A - GIS Application Description Forms
- Appendix B
- Appendix C - Sample GIS Application Description
- Appendix D
- Appendix E - Sample Application Descriptions and Summary Tables
- Glossary
1. INTRODUCTION
A needs assessment is the first step in implementing a successful GIS within any local government. A needs assessment is a systematic look at how departments function and the spatial data needed to do their work. In addition to the final needs assessment report that is generated, intangible benefits are realized by an organization. Conducting a GIS needs assessment fosters cooperation and enhanced communication among departments by working together on a common technology and new set of tools. Finally, the needs assessment activity itself serves as a learning tool where potential users in each participating department learns about GIS and how it can serve the department.
A needs assessment is required if the local government will be adopting a GIS throughout the organization. Without a complete needs assessment each department might proceed to adopt their own system and database which may or may not be compatible with those of another department. The largest benefit for a local government adopting a GIS is to realize efficiencies from common "base data" and the sharing of data among departments.
At the conclusion of a needs assessment, an organization will have all of the information needed to plan the development of a GIS system. This information can be grouped into the following categories:
- Applications to be developed. - In evaluating the responsibilities and work flow within a department, certain tasks are identified that can be done more efficiently or effectively in a GIS. These tasks will form the basis of GIS applications. Application descriptions prepared as part of the needs assessment will describe these tasks.
- GIS functions required. - For each application identified, certain GIS functions will be required. These will include standard operations such as query and display, spatial analysis functions such as routing, overlay analysis, buffering, and possibly advanced analysis requiring special programming.
- Data needed in the GIS database. - Most departments in local government use data that has a spatial component. Much of this data are hard copy maps or tabular data sets that have a spatial identifier such as addresses and zip codes or X-Y values (latitude-longitude, state plane coordinates, or other coordinate system). A needs assessment will identify how this information will be used by GIS applications.
- Data maintenance procedures. - By looking at the work flow and processes within and between departments, responsibility for data creation, updates and maintenance will become apparent.
Note: The needs assessment procedure refers to a local government and its departments as the organizational units. In a multi-agency GIS cooperative, the same activities described would be carried out by all participants, at the appropriate level of detail as determined by the role each participant would play in the resulting GIS cooperative.
Once all of this information is collected and analyzed for each department and published in a report, it can be used as a blueprint for implementing the GIS. The GIS coordinating group within the organization will use it to:
- Design the GIS database
- Identify GIS software that will meet the government's needs
- Prepare an implementation plan
- Start estimating the benefits and costs of a GIS
A common mistake in performing a needs assessment is to simply take an inventory of the maps and spatial data currently used in each department. There are two major problems with this approach. First, this does not allow the GIS coordinating group to evaluate how a GIS could be used to enhance the work of each department and the agency as a whole . By looking at the department functions and what the department does or produces, the GIS coordinating group and potential users develop an understanding of the role GIS can play in the organization. The existing data and maps do need to be inventoried and may well be used in building the GIS, however such an inventory should be separate from the needs assessment.
The second major problem with the "data inventory" approach is that it tends to focus only on data internal to the organization. Local governments rely heavily on data from outside sources - federal agencies, state agencies, business, etc. The need for these data is better determined by looking at the potential GIS applications and how data will be used by each application. It can then be determined what data should be acquired from other sources.
2. CONDUCTING A NEEDS ASSESSMENT
The most significant aspect of a needs assessment is to document the findings in a standard and structured manner. It is very important to adopt (or develop) a standard method to be used for the description of all the GIS tasks, processes and data that will be included in the needs assessment. These forms will be used in needs assessment to identify the three kinds of GIS requirements:
- GIS applications - these will be tasks that can be performed by the GIS when a user requires them, such as preparing a map, processing a query, or conducting some particular GIS analysis. GIS applications can be described using the five page GIS Applications forms included with this guide as Appendix A.
- GIS activity - these are situations where information needs to be kept on some activity or process important to the user, such as issuing building permits, conducting public health inspections, etc. A GIS activity can be described using pages 1 and 4 of the GIS Applications forms - the main application form and the data flow diagramming (DFD) form.
- GIS data - there will be certain categories of spatial data that are important to keep, but which will not appear in any GIS application or activity identified in any application description. A separate method must be developed to systematically record the need for such data. Other GIS data needed but not included in either of the above categories, can be entered directly into the master data list.
The main method used to collect the information to enter onto the forms is individual interviews. Potential users of the GIS can be identified by management and by examination of the organization chart. A series of one-on-one interviews is the best way to identify the users needs. During the interview, the user can usually identify documents that can provide additional information to the GIS analyst.
The needs assessment activity is composed of two main parts:
- Interviewing and documenting the needs of potential GIS users
- Compiling the results of the needs assessment into the master data list and the list of GIS functions.
These two lists respectively are used to prepare the GIS data model and the GIS specifications (activities described under Conceptual Design).
The interview process should identify and describe all anticipated uses of the GIS. The next section briefly describes the major categories of GIS use, followed by a detailed description on how to complete the needs assessment forms.
3. LOCAL GOVERNMENT USES OF GIS
The use of geographic information systems by local government falls into five major categories:
- Browse
- Simple display (automated mapping);
- Query and display;
- Map analysis; and
- Spatial modeling.
Browse
This function is equivalent to the human act of reading a map to find particular features or patterns. Browsing usually leads to identification of items of interest and subsequent retrieval and manipulation by manual means. For single maps, or relatively small areas, the human brain is very efficient at browsing. However, as data volumes increase, automated methods are required to effectively extract and use information from the map.
Simple Display
This GIS function is the generation of a map or diagram by computer. Such maps and diagrams are often simple reproduction of the same maps used in a previous manual oriented GIS environment. Examples of this type of use are preparation of a 1:1000-scale town map, a sketch of an approved site plan, maps of census data, etc.
Query and Display
This function supports the posing of specific questions to a geographic database, with the selection criteria usually being geographic in nature. A typical simple query would be: "draw a map of the location of all new residential units built during 1989" A more complex query might be: "draw a map of all areas within the town where actual new residential units built in 1989 exceeds growth predictions." Such a query could be part of a growth management activity within the town. Queries may be in the form of regular, often asked questions or may be ad hoc, specific purpose questions. The ability to respond to a variety of questions is one of the most useful features of a GIS in its early stages of operation. In the long run, other more sophisticated applications of the GIS may have a higher value or benefit, but to achieve these types of benefits, users must be familiar with the GIS and its capabilities. Such familiarization is achieved through the use of a GIS for the simpler tasks of query and display.
Map Analysis (Map Overlay)
This involves using the analytical capabilities of GIS to define relationships between layers of spatial data. Map analysis is the super-imposition of one map upon another to determine the characteristics of a particular site (e.g., combining a land use map with a map of flood prone areas to show potential residential areas at risk for flooding). Map analysis (often termed overlay or topological overlay) was one of the first real uses of GIS. Many government organizations, particularly those managing natural resources, have a need to combine data from different maps (vegetation, land use, soils, geology, ground water, etc.). The overlay function was developed to accomplish the super-imposition of maps in a computer. The data are represented as polygons, or areas, in the GIS data base, with each type of data recorded on a separate "layer." The combination of layers is done by calculating the logical intersection of polygons on two or more map layers. In addition to combining multiple "layers" of polygon-type data, the map overlay function also permits the combination of point data with area data (point-in-polygon). This capability would be very useful in a town for combining street addresses (from the Assessor's files) with other data such as parcel outlines, census tract, environmental areas, etc. Many facility siting problems, location decisions, and land evaluation studies have successfully used this procedure in the past.
Spatial Modeling
This application is the use of spatial models or other numerical analysis methods to calculate a value of interest. The calculation of flow in a sewer system is an example of spatial modeling. Spatial modeling is the most demanding use of a GIS and provides the greatest benefit. Most spatial modeling tasks are very difficult to perform by hand and are not usually done unless a computerized system, such as a GIS, is available. These models allow engineers and planners to evaluate alternate solutions to problems by asking "what if" type questions. A spatial model can predict the result expected from a decision or set of decisions. The quality of the result is only as good as the model, but the ability to test solutions before decisions have to be made usually provides very useful information to decision makers. Once again, this type of use of a GIS will evolve over time, as the GIS is implemented and used.
A closely related computer capability is a CAD system (computer aided design). CAD systems are used to prepare detailed drawings and plans for engineering and planning applications. While CAD systems functions are different from GIS functions, many commercial CAD products have some of the functionality normally found in a GIS. There are, however, significant differences between a CAD system and a GIS, mainly in the structure of the data base. There may be some need for CAD-type capabilities in a particular local government, so this forms another category of use.
In general, geographic information in local government is used to:
- Respond to public inquiries,
- Perform routine operations such as application reviews and permit approvals, and
- Provide information on the larger policy issues requiring action by the town board.
These are typical local government activities which benefit from a geographic information system. The development of GIS will facilitate the present geographic information handling tasks and should lead to the development of additional applications of benefit to the local government.
There are also other computer systems in local governments that perform GIS-like functions, such as Emergency 911, underground utility locator systems, school bus routing systems, etc. The variety and diversity of GIS applications are what make the definition of a GIS very difficult. Basically, any computer system where the data have one or more spatial identifiers or that perform spatial operations can be classed as a GIS. For example, a system containing street addresses and census tract codes and that has the ability to place a given street address in the proper census tract is a GIS whether or not map boundaries are part of the system. There are two important points here:
- A large proportion of local government data does have one of more spatial identifiers, and therefore has the potential of being part of a GIS.
- Other, existing systems with GIS data or performing GIS-like functions must be integrated into the overall system design. GIS should not be developed as a separate system.
Whether a local government unit is considering or planning a "full, multi-purpose GIS" or is only interested in a limited or single function system, the database planning and design considerations are the same. Only the magnitude of the analysis and design activities differ. Some GIS users believe that smaller and simpler applications, such as a school bus routing system, do not require a formal planning activity. There are, however, several reasons to conduct such a planning activity for the smaller applications:
- To ensure that the user requirements will be fully met
- To develop documentation, especially data documentation (metadata), needed to use and maintain the GIS
- To be in a position to participate in data sharing programs with other agencies as additional applications are developed
- To create a permanent record of the data and its use to document agency plans and decisions, and to meet data retention and archiving requirements.
- To use as a base for building a larger, multi-function at some later date.
The level of effort needed to complete a GIS plan can be kept commensurate with the scope and size of the intended GIS. Further, the GIS planning software tool that accompanies these guidelines provides an easy and convenient way to create the recommended documentation.
4. DATA USED BY LOCAL GOVERNMENT
There are many kinds of data used by local government that can be included in a GIS. Data in a GIS can be one of two types: spatial data and non-spatial data. Spatial data is that data which is taken from maps, aerial photographs, satellite imagery, etc. It is composed of spatial entities, relationships between these entities, and attributes describing these entities. Non-spatial data is usually tabular data taken from tables, lists, etc. Most of the time, the non-spatial data will be linked to one or more spatial entities by keys (unique identifiers associated with the spatial data and non-spatial data). For example, the tax map would represent the spatial data while the real property inventory is non-spatial data, which is linked to the entities (parcels) on the tax map.
Spatial data is commonly represented by geometric objects (points, line, and polygons). Non-spatial data containing a spatial reference is also considered spatial data. One of the most common forms of this type of data in local government are records and files referenced by street address.
Examples of local government data that have been used with GIS include:
| Tax parcels | Land use maps |
| Real property inventories | Zoning maps |
| Infrastructure data | Planimetrics |
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| Census data | Permit records |
The operations required in a GIS must meet the data handling requirements of the spatial data as well as those of the non-spatial data. The most common use of a GIS in local government is the query based on attribute keys and then displayed in map form.
5. DOCUMENTING GIS NEEDS
The GIS needs are documented using the following forms:
A. The GIS Application Description (5 pages), used to:
- Describe products (mostly map displays) produced by the GIS
- Describe activities supported by the GIS
B. The Master Data List
Most GIS applications can be described using the GIS Application Description. In cases where these forms are not appropriate, any other systematic description of the need can be used. If more appropriate, different forms can be developed as long as the same information can be systematically recorded: the data required and the GIS functions need to develop the GIS product.
The set of forms used to document a GIS contains the following five pages:
1. GIS Application Description Form
Use this form to enter:
- Application identification information
- Application description and purpose
- Type of application, map scale, query key, frequency, and required response time
- Data needed by the application
- Entities (features)
- Attributes of entities
2. Map Display Form
Use this form to draw a sample of any maps to be produced by the application
(including the legend showing symbols for each feature). This can be a
hand drawn sketch, although it should be drawn to the scale of the output
desired.
3. Table Display Form
Use this form to show samples of any tables to be produced by the application
(used only if tables are needed in the application). If any entries in
the table involve complex calculations, these should be described using
either a Data Flow Diagram or other separate pages.
4. Data Flow Diagram
Use this form to draw a data flow diagram or flow chart when an application
is complex. This chart is usually drawn by the GIS analyst or someone
else familiar with the diagraming techniques, and is used to document
complex calculations or descriptions of activities that will need GIS
support.
5. Entity-Relationship Diagram
Use this form to draw an entity-relationship (E-R) diagram of the data
used in the application. This drawing is usually done by the GIS analyst
or someone else familiar with the E-R technique, and is only done for
more complex GIS applications.
6. DOCUMENTING AN ACTIVITY-TYPE USE OF THE GIS
Some GIS applications in local government do not involve the production of maps and tables. For example, a GIS may be used to record and store information about a building permit application, a subdivision plat, a site plan, etc. Many activities of local government are simply the processing of permits from individuals or firms. If any of these activities will also generate GIS data, they should be described for the needs assessment. Two techniques available for describing processes are flow charts and data flow diagrams.
A completed application description for a local government activity of this type can be entered on pages 1 and 4 of the GIS Application Description forms.
7. THE MASTER DATA LIST
The master data list is a composite of all data entities (features) and their attributes that have been entered in the data section of the GIS Application Description (Page 1). Other data identified by users as "needed," but not included in any application description may be entered directly into the master data list.
Figure 3 - Master Data List
Master Data List |
||
Entity |
Attributes |
Spatial Object |
|---|---|---|
| Street_segment | name, address_range | Line |
| Street_intersection | street_names | Line |
| Parcel | section_block_lot#, owner_name, | Polygon |
| owner_address, site_address, area, | ||
| depth, front_footage, | ||
| assessed_value, last_sale_date, | ||
| last_sale_price, size, owner_name, | ||
| owner_address, assessed_value (as | ||
| of previous January 1st) | ||
| Building | building_id, date_built, | Footprint |
| building_material, | ||
| building_assessed_value | ||
| Occupancy | occupant_name, occupant_address, | None |
| occupancy_type_code | ||
| Street_segment | name, type, width, length, | Polygon |
| pavement_type | ||
| Street_intersection | length, width, traffins_flow_conditions, | Polygon |
| intersecting_streets | ||
| Water_main | type, size, material, installation_date | Line |
| Valve | type, installation_date | Node |
| Hydrant | type, installation_date,pressure, | Node |
| last_pressure_test_date | ||
| Service | name, address, type, invalid_indicator | None |
| Soil | soil_code, area | Polygon |
| Wetland | wetland_code, area | Polygon |
| Floodplain | flood_code, area | Polygon |
| Traffins_zone | zone_ID#, area | Polygon |
| Census_tract | tract#, population | Polygon |
| Water_District | name, ID_number | Polygon |
| Zoning | zoning_code, area | Polygon |
8. CONDUCTING INTERVIEWS
Individual interviews are the most effective way of finding out from users their potential GIS applications. Before starting interviews, a briefing session for all potential users should be held. During this meeting, the interviewers should describe the entire needs assessment procedure to all participants. The main activities will be:
- Conduct "start-up" seminar or workshop
- Interview each potential user
- Prepare documentation (forms) for each application, etc.
- Review each application description with the user
- Obtain user approval of and sign-off for each application description
An introductory seminar or workshop with all potential users in attendance is useful to prepare the way for user interviews. At the beginning of a project, many users may not have much knowledge about GIS or how it might help them. Also, the interview team may be from outside the organization and may not be very familiar with the structure of the particular local government. The start-up seminar should address the following topics:
- Definitions:
- What is a GIS?
- How is a GIS used by local government? (Typical applications)
- Interview procedure to be followed:
- What the interviewee will do?
- What is expected from the interviewee?
- Who approves the application descriptions?
- How the information from the application descriptions will be used?
- Group discussion: It is often useful to have the group identify an initial set of GIS applications as candidates for further documentation. The discussion of possible applications between interviewers and users will start to reveal what is suitable for a GIS application. One or more applications can be described in the process by the group so everyone sees how the process will work.
It is preferable to interview users individually rather than in groups. This provides a better opportunity to explore the ideas of each person and also prevents other individuals from dominating any particular meeting. Group meetings easily lose focus on specific GIS applications and therefore do not provide the detailed information needed to adequately describe the GIS applications.
Conducting an interview is not an easy task. Some potential users may have a good grasp of GIS and how they might use one. However, often potential users do not have complete knowledge of the capabilities of a GIS and therefore may not be able to readily identify GIS applications. In these cases, the interviewer (GIS analyst) needs to help the user explore his/her job activities and responsibilities to identify GIS opportunities. The GIS analyst should usually begin an interview with a review of the procedure, then ask the user to identify and describe potential applications. When specific GIS applications cannot be easily identified, it is helpful if potential users describe, in general, his/her job functions and responsibilities and the role their department plays in the whole organization. From this discussion, the GIS analyst can usually identify potential GIS applications and then explore these for possible inclusion in the needs assessment.
9. PREPARING THE NEEDS ASSESSMENT REPORT
The needs assessment report consists of the application descriptions, the master data list, and several summary tables. A list of all applications summarizing the type and frequency of use is the first table.
Figure 5 - List of GIS Applications
| App # | Application Name | Type | Frequency |
|---|---|---|---|
| 1 | Zoning Query | Query & Display | 85 / day |
| 2 | Customer Phone Inquiry | Query & Display | 100/day |
| 3 | Fire Dispatch Map | Query & Display | 86/day |
| 4 | Fire Redistricting Map | Map Analysis | 1/year |
| 5 | Crime Summary Map | Query & Display | 12/month |
| 6 | Patrol Dispatch Map | Query & Display | 133/day |
| 7 | Complaint Summary Map | Query & Display | 624/year |
| 8 | Subdivision Development Map | Query & Display | No estimate |
| 9 | Counter Query Map | Query & Display | 85/day |
| 10 | Land Use/Land Value | Map Display | 1/year |
| 11 | Assessed Value Map | Query & Display | 144/year |
| 12 | Grievance Map | Query & Display | 2500/year |
| 13 | Comparable Value Map | Query & Display | No estimate |
| 14 | Built/Vacant Map | Display | 1/year |
| 15 | Water and Sewer Line Map | Query & Display | 30/month |
| 16 | Hydrologic Profile Map | Spatial Model | 1440/year |
| 17 | Sewer System Flow Analysis | Spatial Model | 12/year |
| 18 | Emergency Repair Map | Query & Display | 110/year |
| 19 | Storm Drainage Map | Spatial Model | 700/year |
| 20 | Fire Flow Test Map | Spatial Model | 260/year |
| 21 | Easement Map | Query & Display | 520/year |
| 22 | Zoning Map | Query & Display | 50/day |
| 23 | Floodplain Map | Query & Display | 50/day |
| 24 | Youth League Residency | Check Query & Display | 3500/year |
| 25 | Mosquito Control Area Map | Query & Display | 50/year |
| 26 | Site Plan Approval Process | Query & Display | 200/year |
| 27 | Census Data Map | Display | 48/year |
| 28 | Population Density Map | Map Analysis | 50/year |
| 29 | Land Use Inventory | Display | 24/year |
| 30 | Retail Space Projection | Spatial Model | 24/year |
| 31 | Office Space Projection | Spatial Model | 12/year |
| 32 | Traffic Volume Map | Query & Display | 24/year |
This table contains selected GIS applications from the Town of Amherst, N.Y. Needs Assessment
Figure 6 - Tables Summarizing Applications - Examples
| Department | Display | Query & Dispatch | Map Analysis | Spatial Model | Total |
|---|---|---|---|---|---|
| Fire Dispatch | 0 | 3 | 1 | 1 | 5 |
| Police | 0 | 4 | 0 | 0 | 4 |
| Assessor | 2 | 5 | 0 | 0 | 7 |
| Engineering | 3 | 7 | 7 | 0 | 15 |
| Building | 2 | 2 | 0 | 0 | 4 |
| Recreation | 0 | 2 | 0 | 0 | 2 |
| Highway | 0 | 10 | 0 | 1 | 11 |
| Planning | 10 | 12 | 3 | 3 | 28 |
| Total | 17 | 46 | 4 | 10 | 76 |
The data from the table above can be used to prepare tables like the one below, summarizing applications by department and the frequency of applications by department.
| Department | Display | Query & Display | Map Analysis | Spatial Model | Total |
|---|---|---|---|---|---|
| Fire Dispatch | 0 | 94,170 | 1 | 100 | 94,271 |
| Police | 0 | 49,637 | 0 | 0 | 49,637 |
| Assessor | 2 | 23,894 | 0 | 0 | 23,896 |
| Engineering | 18 | 2,049 | 0 | 3,452 | 5,519 |
| Building | 250 | 25,000 | 0 | 0 | 25,250 |
| Recreation | 0 | 3,520 | 0 | 0 | 3,520 |
| Highway | 0 | 1,475 | 0 | 10 | 1,485 |
| Planning | 718 | 2,536 | 80 | 40 | 3,374 |
| Total | 988 | 202,281 | 81 | 3,602 | 206,952 |
Numbers in these tables are from the Town of Amherst, N.Y. needs assessment and represent the estimates of GIS use per year. These numbers will be used during the database Planning and Design phase to estimate usage and benefits, of the GIS. In this example, for the Town of Amherst, it is estimated that 2.5 minutes of staff time will be saved for each query giving a total savings of 4.03 years staff time/year (202,281 times 2.5 minutes divided by 60 minutes/hour divided by 2088 hours per year).
The last table relates GIS applications to the data used by each application.
Figure 7 - GIS Applications/Data Item Matrix
| Land Parcels | Roads | Buildings | Water Mains | Fire Hydrants | Wetland Areas | |
|---|---|---|---|---|---|---|
| #1 Leak Detection Map | X | X | X | |||
| #2 Customer Service Report< | X | X | X | |||
| #3 Pressure Test Map | X | X | X | |||
| #4 Hydraulic Model Analysis | X | X | ||||
| #5 Work Crew Schedule | X | X | X |
This matrix is useful in planning and scheduling data conversion. If applications are prioritized, then data needed by high priority applications can be scheduled for conversion early in the conversion process. Also, if some data is not available for some reason, it is possible to determine the affected applications.
The last step in compiling the needs assessment report is to extract the list of GIS functions needed from the application descriptions. This list will include the standard function types of display and query and display plus any other functions included in a data flow diagram or flow chart. Typical examples of such GIS functions are: calculate distance between objects, determine the shortest path through a network, etc. Figure 8 is an example of a GIS functions list.
Figure 8 - GIS Function List
| GIS Functions (from Application Description) | Generic GIS Functions | Candidate GISs | |||||
|---|---|---|---|---|---|---|---|
| ARC/INFO | INTERGRAPH | SYSTEM 9 | |||||
| Basic | Macro | Basic | Macro | Basic | Macro | ||
| Display | Screen Display | ARCPLOT | YES | YES | |||
| Plotter Display | ARCPLOT | YES | YES | ||||
| Generate Report | INFO | YES | YES | ||||
| Query | Attribute Query | INFO | YES | YES | |||
| Spatial Query | Spatial Search | IDENTIFY | YES | YES | |||
| Map Analysis | Overlay | ARC | YES | YES | |||
| Buffer | ARC | YES | YES | ||||
| Reclassify | ARC | YES | YES | ||||
| Shortest Path | Shortest Path | NETWORK | NO | YES | |||
| Route | Route | NETWORK | NO | YES | |||
| Hydraulic Model | AML | YES | YES | ||||
The list of GIS functions and the master data list will be used in subsequent tasks to design the database and prepare the GIS specifications.
10. SUMMARY
The procedure presented in the guideline for preparing a needs assessment is based on documenting GIS applications in a standard format. The components of this format are structured to facilitate communication between potential GIS users and the GIS analyst, and to provide specific and detailed information to the GIS analyst for designing the GIS. The first page of the application description is the most critical to the GIS analyst as an indication of the GIS functionality required by the application. If additional information on the GIS functionality is needed, than a flow chart or data flow diagram can be developed (page 4 of the application description). For the potential user, the map display and report format describe output he/she will receive. These pages should be sufficiently detailed for the user to approve or sign-off as to the correctness of the application description. It is, of course, very important that the entire GIS application description be internally consistent.
The entity-relationship diagram (page 5) is mainly useful in the next phase of the GIS design - Conceptual Design, where the data model for the entire system will be defined. If entity-relationship diagrams are prepared for individual applications, they will than be available for the Conceptual Design phase. Otherwise, these diagram can be prepared during the Conceptual Design phase.
Figure 9 is a diagrammatic representation of the flow of information from the elements of the application description to the master data list and the list of GIS functions.
Appendix A - GIS Application Description Forms
| GIS Application Description Form | A-1 |
| Map Display Form | A-2 |
| Table Display Form | A-3 |
| Data Flow Diagram | A-4 |
| Entity-Relationship Diagram | A-5 |
Appendix B
| Master Data List | B-1 |
Appendix C - Sample GIS Application Descriptions
*Note: This is not available in electronic format. You may obtain a paper copy of these guidelines by contacting RECMGMT@mail.nysed.gov.
Appendix D - Data Flow Diagramming
*Note: This is not available in electronic format. You may obtain a paper copy of these guidelines by contacting RECMGMT@mail.nysed.gov.
Appendix E
| List of Application Name, Type, & Frequency | E-1 |
| Application Descriptions | E-2 (35.6K) |
| Master Data List | E-17 |
| Summary Table of Depts. & Counts of Application Type | E-21 |
| Summary Table of Depts. & Annual Frequencies of Application Type | E-22 |
