GEOGRAPHIC INFORMATION SYSTEM
STANDARD GIS SOFTWARE
Arc info was developed by Environmental Systems Research Institute (ESRI), Redlands, California, USA.Arc Info data structure Arc Info is a vector- based GIS package, capable of handling both spatial and non-spatial data. It organizes geographical data using vector topological models and non-spatial data using relational models in a DBMS. The arc node and polygon topology are organized to identify points, lines, and polygon relations. The cartographic data are then linked to the attribute data through a link item.
Arc Info functionalities : Arc Info has a wide range of functions which have been developed based on a tool-box concept -where each function can be visualized as a tool and having a specific utility. The major modules of Arc Info functionalities are :
(a) ADS and ARCEDIT: data base creation in Arc Info is possible through the process of digitisation using the Arc Digitising System(ADS) and the ARCEDIT module. ARCEDIT is a powerful editing utility having capabilitiesfor feature -based editing. These modules include the functions for coordinate entry using different devices - digitisers, screen cursors and so on;
(b) INFO: INFO is the manager for tabular data associated with geographic features in map coverage of Arc Info. INFO provides facilities for data definition of data files, use of existing data files, data entry and update and, sorting and querying;
(c)Analysis Modules: Arc Info offers spatial overlay capabilities based on topological overlay concepts. Union/ intersect overlays, buffer generation, proximity analysis, feature aggregation, feature extraction, transformation, nearness functions and other integration utilities are available;
(d) ARCPOLT: This module has capabilities for generating cartographic quality outputs from the database. This includes utilities for interactive map composition, editing map compositions, functionality, the incorporation of coverage features to the required scale, generalisation, symbolisation, transformation, and so on. Placement of non-coverage features, include legends, free text, and logos, graphic elements.
(e) TIN: The TIN module of Arc Info can be used to create, store, manage, and perform analysis pertaining to the third dimension data. The modeling capabilities include calculation of slope, aspect, isolines or contouring range estimation, perspectives, and volumes. Additional functions for determining spatial visibility zones and line of sight are also provided;
(f) NETWORK: The NETWORK module of Arc Info performs two general categories of functions: network analysis and address geocoding. Network analysis is p05sible for optimal path determination and resource allocation analysis. The geocoding module allows for associating addresses to line networks and determining the spatial framework of addresses in an application;
(g)COGO: It is the coordinate geometry module of Arc Info; supports the functions performed by land surveyors and civil engineers for the design and layout of sub-divisions, roads and related facilities, as well as the special plotting requirements. COGO allows definition, adjustment and close traverse including adding curves on a traverse; it computes area, bearing and azimuths;
(h) GRID is a raster-based module of Arc Info. GRID has an interface to Arc Info, so coverage can be converted to GRID and from GRID to Arc Info. GRID supports powerful modeling tools of raster integration, potential mapping, spread/grow operations and so on.
Arc Info also supports ERDAS system, OEM data, Autocad -DXF format, IGES format and a flat file format. ARCVIEW module is a desktop mapping package oriented towards viewing and querying Arc Info databases.
GIS MAPPER : It is the basic module for data entry to create a data base of maps by generation and editing of the vector database, which forms the base for subsequent raster - based analysis. It includes Planner, for quick interactive report generator. GIS MAPPER also supports pen plotter output to several plotters;
ANALYSER : This module allo~s the user to perform data conversion forpolygonisation: raster creation from the v~ctor boundaries of the polygonal areas , overlay operations for two or more polygonal overlays to generate another level of output, proximity analysis, and corridor analysis around specified map features TOPOGRAPHER: This is for processing of three dimensional data and Dem. Different products like slope, aspect, perspective views, and volume calculations can be derived from this module;
INTERPRETER: This is for importing remotely sensed images from digital image analysis system in to the PAMAP GIS as surface covers.
MODELLER : This module integrates multiple -surface rasters or multiple data base attributes to make planning decisions quickly and accurately. It has three main functions - combination of modeling, regression analysis and correlation, and covariance analysis; NETWORKER : This module is used to create, analyse, and manage networks.
FILE TRANSLATOR: This is for importing and processing map files created in various data formats like IGDS, SIF (Intergraph), DLG and DXF (Autocad).
PAMAP platforms : This is available on variety of platforms -on pentium 486 PCs; UNIX workstations and VAX systems and also on MS Windows with multitasking capability.