Introduction to Maps
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The document provides an introduction to mapping and Geographic Information Systems (GIS), covering concepts of maps, types of maps based on scale and purpose, and the advantages and limitations of paper-based versus digital maps. It explains cartographic principles, the significance of map design elements, and the differences between raster and vector data. Additionally, it highlights how digital mapping enhances representation and updates of geographical data compared to traditional paper maps.
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Introduction to Maps
- 1. INTRODUCTION TO MAPS (GEOGRAPHICAL INFORMATION SYSTEM) UNIT – I Dr. Rambabu Palaka, Professor, BVRITSep. 2020
- 2. Syllabus 1. Mapping Concepts 2. Analysis with paper based Maps 3. Limitations of Paper based Maps 4. Computer Aided Cartography History and Development 5. GIS Definition 6. Advantage of Digital Maps
- 4. Mapping Concepts A map is a two dimensional representation of earth surface which uses graphics to convey geographical information. It describes the geographical location of features and the relationship between them. Most maps have keys and scales that help the reader understand the map. The key explains symbols and colors used on the map, so you know what they represent. Scales tell you the relationship between the size of the map and the size of the place in real life.
- 8. Map Scale Map Scale The size of earth is too big to be represented as it is on a map. To represent the whole earth or part thereof on a small map, the concept of scale is used. Representation of Scale: 1. Statement: Expressed in words such as ‘1 centimeter to the kilometer’ which means one centimeter on the map represents one kilometer on the ground. 2. Representative fraction: It is expressed in fraction. If the scale is 1:50000, it means that 1 unit of measurement on map represents 50,000 units on ground. It is also known as numerical scale. 3. Graphic: The scale is shown in form of a strip, where the strip is divided into a number of equal parts and is marked to show what these divisions represent on actual ground. It is also known as plain scale or linear scale.
- 12. (a) 1:25,000 [Large scale] (b) 1:50,000 [Small scale]
- 14. Types of Maps The maps can be classified on the following criteria: 1. Scale: Scale is important for correct representation of geographical features and phenomenon. Different features require different scales for their display. For example preparation of a cadastral map of a village and the soil map of a state would use different scale for representing the information. According to scale, maps can be classified as follows: a) Cadastral Maps - These maps register the ownership of land property b) Topographical Maps - These maps are prepared on fairly large scale and are based on precise survey c) Chorographical/Atlas - Drawn on a very small scale, atlas maps give a generalized view of physical, climatic and economic conditions of different regions of the world. The scale of atlas map is generally greater than 1:1000,000. 2. Purpose a) Natural Maps b) Cultural Maps
- 15. Types of Maps Maps based on Purpose 1. Natural Maps - These maps represent natural features and the processes associated with them a) Astronomical map b) Geological map c) Relief map d) Climate map e) Vegetation map f) Soil map 2. Cultural Maps a) Political map b) Military map c) Historical map d) Social map e) Land-utilization map f) Communication map g) Population map
- 16. Natural Maps These maps represent natural features and the processes associated with them. Given below is the list of some such maps: 1. Astronomical map: It refers to the cartographic representation of the heavenly bodies such as galaxies, stars, planets, moon etc. 2. Geological map: A map that represents the distribution of different type of rocks and surficial deposits on the Earth. 3. Relief map: A map that depicts the terrain and indicates the bulges and the depressions present on the surface. 4. Climate map: A climate map is a depiction of prevailing weather patterns in a given area. These maps can show daily weather conditions, average monthly or seasonal weather conditions of an area. 5. Vegetation map: It shows the natural flora of an area. 6. Soil map: A soil map describes the soil cover present in an area.
- 17. Cultural Maps These maps tell about the cultural patterns designed over the surface of the earth. They describe the activities of man and related processes. Given below is the list of such maps: 1. Political map: A map that shows the boundaries of states, boundaries between different political units of the world or of a particular country which mark the areas of respective political jurisdiction 2. Military map: A military map contains information about routes, points, security and battle plans. 3. Historical map: A map having historical events symbolized on it. 4. Social map: A map giving information about the tribes, languages and religions of an area. 5. Land-utilization map: A map describing the land and the ongoing activities on it. 6. Communication map: A map showing means of communication such as railways, road, airways etc. 7. Population map: A map showing distribution of human beings over an area.
- 18. The map and the globe are similar in a manner that both of them represent earth (on particular scales) but there also exist a few differences between them, which are enumerated below:
- 19. Cartographic Principles & Design Cartography is the art and science of map making. Cartographers make a huge contribution in making the maps more meaningful and understandable. Major principles of cartography: Data Classification - It is important to have a good understanding of the data which needs to be represented on a map. The scales of measurement used are described below: a) Nominal Scale - It only satisfies the identity property b) Ordinal Scale - This scale has the properties of both identity and magnitude but the interval between any two values is indeterminate. c) Interval Scale - This scale has the properties of identity, magnitude and equal intervals d) Ratio Scale - The ratio scale has the properties of identity, magnitude, equal interval and absolute zero
- 21. Map Layout The process of map composition starts with preparing a layout for the map. Apart from the data, a map has certain other things that make map a package of effective and clear communication. These provide critical information to users and are known as map elements. A layout specifies the space and positions for different map elements such as neat lines, title, North arrow, scale bar, legend etc.
- 24. Map Elements 1. Color - The aim of filling colors in a map is to make visual distinction among various features thus making map more decipherable. Generally, dark colors mean more and represent high values of the attribute under study a) Additive Color Model b) Subtractive Color Model - A subtractive color model explains the mixing of dyes, inks etc. to create a range of colors. 2. Text 3. Placement of Labels 4. Symbols a) Shape b) Size c) Combination of Symbol and Color
- 27. Toposheet Indexing Survey of India produces the topographic maps of India. These maps are produced at different scales. In order to identify a map of a particular area, a numbering system has been adopted by the Survey of India.
- 31. Raster Maps vs Vector Maps Raster data is any data that is continuous; in the form of pixels. An example of raster data is digital imagery, having data stored in pixels. Vector data, on the other hand, is discrete and has attributes stored against geometric features. An example of vector data set can be data for a city’s road network. Roads can’t exist on every meter of land so their data cannot be continuous. Roads also have attributes like names, thickness, length, etc. Vector and Raster tiles are different in the same way as data. Raster tiles are images whereas vector tiles have underlying geometry and attributes of features on the top.
- 35. Limitations of Paper based Maps 1. Time consuming: They require complex interpretations when reading them. 2. Good quality paper maps may be hard to find. 3. Map printing errors 4. Paper maps can easily be damaged 5. Paper maps are limited: Paper maps only show limited areas on a single map and you will need several maps if you are visiting several destinations. 6. It is archaic: Paper maps are an old way of representing an area on a map and may be difficult to understand 7. Paper maps are not complete: Paper maps are never complete and one may never get a complete paper map of an area. This is because features and landscapes keep on changing. 8. Paper maps are biased: Paper maps are designed and printed by people whose perception of an area may be subject to personal bias.
- 36. Limitations of Paper based Maps 9. Paper maps show limited features: Paper maps show limited features of a given area on the paper because they only concentrate on one aspect of the landscape. 10. Paper maps are complicated to understand: Paper maps are difficult to understand because most of the features are represented in symbols. 11. Paper maps only use symbols: Paper maps rely solely on symbols to represent important features on the map and this may be a problem during interpretation. 12. Difficult to show elevation: It is difficult to show elevation on a paper map because of the limited representation features.
- 37. Digital mapping (also called digital cartography) is the process by which a collection of data is compiled and formatted into a virtual image. The primary function of this technology is to produce maps that give accurate representations of a particular area, detailing major road arteries and other points of interest. Digital Cartography involves the creation and analyses of maps through the use of computers. As such, Geographical Information Systems (GIS) are an integral tool for Cartography. A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present spatial or geographic data. Digital Maps
- 38. Both GIS and traditional maps represent the real world. One way of thinking about it is that the GIS is the data while the map is the picture. The end result of GIS analysis is often a map, or cartographic output, but it is only one of many output types. Once created, a traditional map cannot be changed. However, as an integrated system, a GIS allows users to ask new questions of a database and visualize answers. Difference between Digital Map and a Traditional Map
- 39. Advantages of Digital Maps 1. They can be downloaded for free: Digital maps are not sold in physical shops but instead they are available online and can be downloaded for free. 2. Storage requires digital space: Digital maps do not require physical space for storage. They are stored in digital format and therefore require digital space. 3. Shows all features including time and the actual building: Digital maps do not depend on symbols to represent features. Instead, they show the actual features and the time. 4. Can be easily updated: Digital maps are mostly real time representations of an area and can therefore be updated easily because the changes will be updated automatically. 5. It is dynamic: Digital maps are dynamic which means one can choose to view the previous versions of the represented area unlike paper maps.
- 40. Advantages of Digital Maps 6. Digital maps can represent all features at the same time: Digital maps can be used to represent all features of a given area at the same time. They allow filtering for specific features but can also show the entire area. 7. Digital maps are not limited to any area: Digital maps are not limited to show only a specific area based on scale. They can be widened to show the entire area. 8. May not require special skills since it shows the real life object: Interpreting digital maps is easier than paper maps since the features are real representations of the real world objects. 9. Good at showing area overlays from various angles: Digital maps do not only show 2D representations of an area. They can be used to show the 3D angle of the area and also show the area overlays. 10. Digital maps are always up to date