Storing Nontopological Geometry as Vector Data in CAD and Shapefiles (Especially for GATE-Geospatial 2022)

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A shapefile stores nontopological geometry and attribute information for the spatial features in a data set. The geometry for a feature is stored as a shape comprising a set of vector coordinates. Because shapefiles do not have the processing overhead of a topological data structure, they have advantages over other data sources such as faster drawing speed and edit ability.

Types of Nontopological Vector Data

There are two types of nontopological vector data.

This Diagram Shows Two Types of Nontopological Vector Data

1. Computer Aided Design

Computer-aided design (CAD) is a system of hardware and software used by design professionals to design and document real-world objects.

These systems are designed to accommodate a wide range of applications. Organizations involved in the engineering, architecture, surveying, and construction industries use them to provide a variety of services.

CAD data can serve a range of purposes β€” from a design plan that is printed as a drawing or submitted as a legal document, to a repository for ongoing as-built information.

2. Shapefile

Shapefile is a standard Nontopological data format. Geometry of a shapefile is stored in two basic files:

  • The . shp file stores the feature geometry.
  • The . shx file maintains the spatial index of the feature geometry.
  • The . dbf file stores attribute information for files in a dBASE file
  • The. sbn and . sbx files store the spatial index of a feature. ArcView partitions the geographic features into spatial β€˜bins.’

The record number of each feature is stored and ArcView uses the file to speed up spatial queries and redraws the theme.

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