• ภาษาไทย
  • English

Geo-Informatics and Space Technology Development Agency (Public Organization):GISTDA

GISTDA To be Value based Organization in Geo-space Intelligence Deliveries by 2020

Map Conclusion and Projections

Map Conclusion and Projections

1. Map Projections

         Map projections and coordinate system in mapping are important for position specification on the earth, which is transferred to flat map. The coordinate system enables us to know material’s point and position on the earth through Meridian Line dividing the earth into parts based on angular distance or meridian called Geographic Coordinates.
       The Geographic Coordinates are transferred to map through three-dimension and two-dimension vector systems. Several types of map projections present different characteristics: area keeping, shape and directions influencing on selecting consideration in using it to present different types of map data in different areas and content. Map projections are different due to different types of lines: plane, funnel-shaped and cylinder, including characteristics of light source that affects different characteristics of map projections and is used to consider appropriate mapping. The popular map projection is Universal Transverse Mercator (UTM), which is from the use of cylinder as map projection with globe model on the Meridian line. It is used to correctly present long north-south area. This type of projections is used in UTM coordinate system in making geographic map and base map in all around the world.

2.Types of Map and Symbol Design

        Map is an important tool in using and planning in any fields of study. Map classification is processed based on physical features and usage of the map. Fundamental principle of map use is making understanding map elements and symbol content appearing on the map for communication between map users and makers. Designing map symbols should then be appropriate and communicable to allow the users who lack of basic knowledge towards map can easily understand without reading any legends. It must also be appropriate in terms of size, color and design to attract the readers and ease their reading.
         Moreover, map scale is another variable causing different types and usage of map. Map scale calculation can be processed by comparing distance between two points in the real geography with distance on the map. The scale is also divided into vertical and horizontal scales, which are differently calculated, including different features such as wording or line scales.

3. Map Reading

       Reading map depends on symbol interpretation since the symbols are representatives of real complicated geographic characteristics. Map symbols present height line indicating geographic height, including different geographic data when looking from the hill, cliff or defile. The map readers must look at height line sequence, curve and smoothness to understand the map as they have to effectively interpret the height line in order to translate meaning from real geographic characteristics.
        Moreover, at present application of map is still necessary because map represents spatial data, and any activities held on the earth can be presented on the map in order to use it correctly based on the characteristics of data. Therefore, map is widely used and it is increasingly used in some specific events such as cancer patient dispersing map or location and investment map in the area of Suthep Road, etc. It obviously shows that map is used for several purposes and applied with other fields of study, not only geography, meteorology or geology but also medicine, environment and social work. There are two types of reading and using map in geography: intersection and resection. The intersection uses map to find located position of two landmarks while the resection finds the position of map user following references from the landmarks. There are two types of tools: compass and protractor and line or graphic.

4. Making Maps

         Map making aims to present geographic data through appropriate symbols. Map design must then emphasize accurate data in communicating spatial data that is well-matched with real geographic characteristics. Map is an academic document used as a research instrument presenting research findings and communicating data. Good map design should be clear and not wordy so that the users can quickly understand, apply and easily recognize map data.
         Map design consists of major principles: image-background, visual balance, contrast and hierarchical organization. Practical steps of map design begins with specifying presentation media such as electronic media or printing media. Then selecting map scale and projections, analyzing map content, finding out appropriate symbols to serve the objectives and organizing map elements such as map content, major name, minor name, direction, based on map design criteria. When the design is completed, it is finally printed for checking. Moreover, it should be presented to the map users to cooperatively check.