Georeferencing is the process of assigning real-world coordinates to each pixel of the raster. These coordinates are obtained by doing field surveys - collecting coordinates with a GPS device for few easily identifiable features in the image or map. In case of digitize scanned maps, the coordinates can be obtained from the markings on the map image itself. Using these sample coordinates or GCPs (Ground Control Points), the image is warped and made to fit within the chosen coordinate system.
Table of Contents
1. GEOREFERENCING OF TOPOSHEET
2. DIGITIZATION OF TOPOSHEETS USING POINT FEATURE
3. DIGITIZATION OF TOPOSHEETS USING LINE FEATURE
4. DIGITIZATION OF TOPOSHEETS USING POLYGON FEATURE
5. CREATION OF DIGITAL ELEVATION MODEL
6. CREATION OF CONTOURS THROUGH DIGITAL ELEVATION MODEL
7. DETERMINATION OF HILLSHADE FOR THE GIVEN TERRAIN
8. DETERMINATION OF SLOPE FOR GIVEN TERRAIN
9. DETERMINATION OF ASPECT FOR GIVEN TERRAIN
10. DETERMINATION OF RELIEF FOR GIVEN TERRAIN
11. DETERMINATION OF RUGGEDNESS OF THE GIVEN TERRAIN
12. DETERMINATION OF MEAN CENTRE FOR GIVEN TERRAIN
13. BUFFER ANALYSIS
Objectives and Themes
This manual provides a practical, step-by-step guide for performing essential Geographic Information System (GIS) tasks using Quantum GIS (QGIS) 1.8. The primary objective is to equip students and practitioners with the methodology to process geographical data, ranging from basic georeferencing and feature digitization to advanced terrain analysis and spatial proximity modeling.
- Georeferencing scanned maps to real-world coordinate systems.
- Digitization techniques for point, line, and polygon feature data.
- Generation and analysis of Digital Elevation Models (DEM).
- Terrain modeling, including slope, aspect, hillshade, and ruggedness analysis.
- Spatial analysis applications such as mean center calculation and buffer modeling.
Excerpt from the Book
1. GEOREFERENCING OF TOPOSHEET
Georeferencing is the process of assigning real-world coordinates to each pixel of the raster. These coordinates are obtained by doing field surveys - collecting coordinates with a GPS device for few easily identifiable features in the image or map. In case of digitize scanned maps, the coordinates can be obtained from the markings on the map image itself. Using these sample coordinates or GCPs (Ground Control Points), the image is warped and made to fit within the chosen coordinate system.
Summary of Chapters
1. GEOREFERENCING OF TOPOSHEET: Explains the process of assigning geographic coordinates to raster images using Ground Control Points.
2. DIGITIZATION OF TOPOSHEETS USING POINT FEATURE: Details the manual conversion of point-based map features into digital vector layers.
3. DIGITIZATION OF TOPOSHEETS USING LINE FEATURE: Describes the methodology for capturing linear map features like roads and railways.
4. DIGITIZATION OF TOPOSHEETS USING POLYGON FEATURE: Covers the creation of closed vector shapes to represent area features like forests and water bodies.
5. CREATION OF DIGITAL ELEVATION MODEL: Outlines the steps to generate a DEM from point elevation data using interpolation.
6. CREATION OF CONTOURS THROUGH DIGITAL ELEVATION MODEL: Explains the generation of contour lines from a processed DEM.
7. DETERMINATION OF HILLSHADE FOR THE GIVEN TERRAIN: Describes how to calculate hypothetical illumination to enhance 3D visualization.
8. DETERMINATION OF SLOPE FOR GIVEN TERRAIN: Provides methods to calculate the rate of change in elevation across a surface.
9. DETERMINATION OF ASPECT FOR GIVEN TERRAIN: Guides the user in identifying the compass direction of maximum surface steepness.
10. DETERMINATION OF RELIEF FOR GIVEN TERRAIN: Details the visualization of terrain relief for cartographic presentations.
11. DETERMINATION OF RUGGEDNESS OF THE GIVEN TERRAIN: Describes the assessment of terrain heterogeneity using a ruggedness index.
12. DETERMINATION OF MEAN CENTRE FOR GIVEN TERRAIN: Covers the statistical calculation of the geographic center of a set of features.
13. BUFFER ANALYSIS: Explains the generation of proximity zones around specific geographic features.
Keywords
GIS, QGIS, Georeferencing, Digitization, Raster, Vector, Digital Elevation Model, DEM, Terrain Analysis, Hillshade, Slope, Aspect, Ruggedness, Proximity Analysis, Buffer
Frequently Asked Questions
What is the primary purpose of this practical manual?
This manual serves as a instructional guide for students and researchers to perform standard GIS operations using Quantum GIS 1.8 for spatial data processing and analysis.
Which GIS software is used in this manual?
The manual utilizes Quantum GIS (QGIS) 1.8 for all described methodologies.
What is the core research goal of the described workflows?
The goal is to enable users to transform raw scanned maps and terrain data into structured, actionable digital information for geographic analysis.
What scientific methods are applied to analyze the terrain?
The manual uses raster-based terrain analysis methods, including the generation of hillshade, slope, aspect, relief, and ruggedness index calculations.
What is covered in the main section of the document?
The document covers the full lifecycle of spatial data manipulation, starting from georeferencing, through vector digitization, to advanced surface modeling and spatial proximity analysis.
Which terms best characterize this manual?
The manual is characterized by terms such as GIS, Digitization, DEM, Terrain Analysis, and Buffer Analysis.
What is the significance of the "Ruggedness Index" mentioned in the manual?
The ruggedness index is used to measure terrain heterogeneity, helping identify mountainous peaks and cliffs by summarizing elevation changes.
How does the manual suggest handling elevation data?
It suggests using Digital Elevation Models (DEM) to extract terrain parameters and model surface characteristics like slope and orientation.
What is the purpose of Buffer Analysis as described?
Buffer Analysis is used for proximity analysis to determine relationships between selected features and their surrounding geographic environment.
How are the generated outputs usually finalized?
The processes are typically finalized by exporting the resulting map compositions as PDF files or images through the QGIS Print Composer tool.
- Arbeit zitieren
- Jagadish Kumar Mogaraju (Autor:in), 2013, Practical Manual for RS and GIS with Quantum GIS, München, GRIN Verlag, https://www.grin.com/document/267283
