5 - Geographic Information System Overview

Overview -

  • Widely used for surveying and mapping.

  • Tools for renewable natural resource management.

  • Predictions.

  • Improved decision-making

Geographic information systems

Why use GIS?

  • Very powerful, can handle enormous amounts of data.

  • Diverse applications (that need geographic locations).

  • Organized like a database -> efficient if well organized.

What GIS is not

  • A computerized system for making maps

  • A tool for storing maps and pictures (data within the GIS is the foundation, not the maps)

Global issues that can be addressed with GIS

  • Ozone layer

  • Global warming

  • Acid rain

  • Pollution, sedimentation, erosion

Daily monitoring by satellites'

  • Weather

  • Vegetation

  • Ocean circulation

  • Land use

  • Other activities

What is a GIS?

A computer-based system that provides four sets of capabilities:

  • Input

  • Management (storage and retrieval)

  • Manipulation and analysis

  • Output

Data input

  • Maps, satellite imagery, attribute data, etc.

  • Can be straightforward (importing Excel files, scanning aerial photos).

  • Or complex (creating new database incorporating large volumes of data).

  • Accuracy is important, regardless of input type.

Data management

  • Computerized database.

  • Ensure that all factors can be related to one another.

  • Database should be organized with forethought of user groups and goals.

  • Data management affects the efficiency of the GIS.

Data manipulation and analysis

  • All activities must be automated.

  • Manipulation may occur within the GIS, or may be conducted outside and imported into the system.

  • Same goes for analysis.

Output

  • Maps, tables, texts, graphs.

  • Most involve graphics.

Aerial Photo Interpretation

Recongnition elements

  • Shape (round, linear, crop field).

  • Size (calculated from known objects).

  • Pattern (plantations, rows).

  • Shadow (can give profile – bridges).

  • Tone/color (conifers vs. hardwoods).

  • Texture (pasture vs. forest).

  • Association (skid trails in clear-cut areas).

  • Site (riparian vegetation along streams).

Topographic maps: good for orientation