What Is A Geographic Features

Tabular array of Contents

FRONT Slice
Affiliate 1: THE NATURE OF GEOGRAPHIC Information
1. MAPS AND SPATIAL INFORMATION
2. CHARACTERIZING GEOGRAPHIC FEATURES
3. Information ACCURACY AND QUALITY
Chapter two: THE NATURE OF GEOGRAPHIC INFORMATION
CHAPTER 3: Data SOURCES
CHAPTER 4: DATA ORGANIZATION AND STORAGE
CHAPTER 5: DATA ANALYSIS
CHAPTER 6: IMPLEMENTATION ISSUES AND STRATEGIES
Affiliate 7: DEVELOPMENTS AND TRENDS

CHARACTERIZING GEOGRAPHIC FEATURES

All geographic features on the earth'south surface tin can be characterized and defined as ane of iii basic feature types. These are points, lines, and areas.

Every geograpic phenomenon can in principle be represented by either a point, line, and/or an expanse.

GIS Data Structures illustrating the departure between Vector and Raster formats (Adapted from Berry)

Commonly, an identifier accompanies all types of geographic features. This description or identifier is referred to every bit a label. Labels distinguish geographic features of the same type, due east.thou. wood stands, from ane another. Labels tin be in the form of a name, e.g. "Lake Louise", a clarification, east.g. "WELL" or a unique number, e.g. "123". Forest stand up numbers are examples of polygon labels. Each label is unique and provides the machinery for linking the characteristic to a ready of descriptive characteristics, referred to as attribute data.

It is important to note that geographic features and the symbology used to represent them, east.g. point, line, or polygon, are dependant on the graphic calibration (map scale) of the data. Some features can be represented past point symbology at a small calibration, e.g. villages on a 1:1,000,000 map, and past areal symbology at a larger scale, due east.g. villages on a 1:10 ,000 map. Appropriately, the accurateness of the feature's location is frequently fuzzier at a smaller scale than a larger calibration. The generalization of features is an inherent characteristic of data presented at a smaller scale.

Data tin always be generalized to a smaller scale, only detail CANNOT be created !

Call back, as the calibration of a map increases, due east.g. 1:15,000 to 1:100,000, the relative size of the features decrease and the post-obit may occur:

	Some features may disappear, east.g. features such equally ponds, hamlets, and lakes, become indistinguishable equally a feature and are eliminated.;
	Features change from areas to lines or to points, e.g. a hamlet or town represented past a polygon at 1:15,000 may change to signal symbology at a i:100,000 scale.;
	Features modify in shape, e.g. boundaries go less detailed and more generalized.; and
	Some features may appear, eastward.k. features such as climate zones may exist indistinguishable at a big scale (ane:xv,000) but the full extent of the zone becomes axiomatic at a smaller scale (1:1,000,000).

Appropriately, the employ of data from vastly different scales will result in many inconsistencies between the number of features and their blazon.

The utilize and comparison of geographic data from vastly different source scales is totally inappropriate and tin atomic number 82 to significant error in geographic data processing.