Types of Maps and Making Symbols
1. Classification and Types of Maps Maps are classified into three types:
• Detailed Maps
- Line maps: The details appearing on the map are straight lines, curve or dashed lines
- Photomaps: The details appearing on the map are aerial photographs of whole or parts of
geography that can be used to replace the map or be an additional part of the map, including grid line, detailed border of map, contour line, geographical name, discontinuity and additional information that can be additionally typed. Moreover, there may be several colors additionally typed to indicate geographical characteristics.
- Annotated maps: Its details is a combination between geographical photo and additional
drawn or written details
• Scale Maps
- Geographical classification consists of three types of scale maps: small scale maps
(˂ 1: 1,000,000), medium scale maps (from 1: 250,000 to 1: 1,000,000) and large scale maps ( ˃ 1: 250,000)
- Military classification also consists of three types of scale maps: small scale maps
(≤ 1:600,000), medium scale maps (from 1:600,000 to 1: 75,000) and large scale maps (≥ 1: 75,000)
• Utilizing Maps This type of maps is classified by utilization types and types of details appearing on the map. In general there are two sub-types of this map types:
- Planimetric map is a map that presents general details of horizontal global surface. It is useful in presenting the positions and finding horizontal distance.
- Topographic map is a map that shows general details of horizontal and vertical global surface (contours). In some cases, there may be the classification of special and thematic maps, which are made based on general map; then using the desired present information overlay them.
- Cadastral map is used to present land tenure scope of each landlord. It is a large-scale map made by surveying earth surface and using aerial photographs.
- Economic map is used to presents population dispersal or density, or products, trade route, transportation, agricultural areas, industrial areas, resources such as mineral and forest sources
- Statistical map is used to present statistical data. It is a small-scale map covering large areas. There are three sub-types: Dot map presenting the data using dots, Isopleth map such as Isobars, temperature, etc., and Choropleth map indicating differences of data using colors or color shade for the data that have similar characteristics.
2. Principles of Map Usage
The map relating to daily life, working performance, education, politics, economy, social psychology and others that enables human to successfully process any tasks, even basic survey, practical or pedagogical levels. The government is able to use geopolitics for country administration towards activities relating to politics, military and environmental, economic and social development. This helps confirm that understanding the map occurs with all-level users. The map users therefore need to understand meanings of symbols and information the maker wants to present. The main principles of map usage are understanding all components and content of the map in both in and out of border. The users should learn and understand correct information and meanings of symbols that enables them to reach their objectives of using each type of map.
Map is a simulation of objects on global surface scaling down based on required scale. These objects consist of natural objects and objects built by human, which presents though symbols, lines, colors and shapes.
4. Map Components
In general, each map is in square shape. There are several types materials used to make a map. It must be durable. Most mops are printed on paper. The four-side contour of the map consists of blocking lines indicating grid coordinates or curve presenting geographical latitude and longitude. As a result, the map is divided into two areas: inside-border area and outside-border area. The outside-border of map is called map border, and the inside-border area are symbols, colors, geographical name and position reference system, etc.
5.Position reference system
The Position Reference System is a coordinate system mentioned in the coordinate system topic.
6. Border Data
The border data means the area from border of the map margin to four-side map margins. It appears on the space out of the border. Map maker presents the information in detailed by aiming at encourage the users’ understanding towards types of maps, which enables them to be able to use the map correctly and appropriately with works. The geographical scale map of 1: 50,000 of The Royal Thai Survey Department is used as an example. The information of border is as follows:
• Series name
Telling the series name of the map to limit the scope of map. Map making may be processed in large areas such as global map, continent map, country map or several countries map; therefore, it is necessary to identify the name of map series with scale; for example, “Thailand 1:50,000” This series name must be typed at the above left corner of the map.
• Sheet name
This is an important part of each map position. It is used to indicate how wide of area the map covers such as Chiang Mai or Yala. If it covers the district areas, use the name of the district. If it covers the village areas, use the name of the village depending on the outstanding characteristics of that areas covered by the map. The sheet name must be typed at the above center of the map, and it must be typed in the biggest size of information, even Thai or English such as “CHANGWAT CHIANG MAI” OR CHANGWAT YALA” The sheet names will be not repeated. The geographical scale is 1:50,000. There are 830 sheets covering the whole country, and there also are 830 sheet names.
• Edition note
The edition note presents number of editions by whom such as “Edition 1-RTSD” typed at the above right and below left of the map. It means that this map is printed for the first time by Royal Thai Survey Department.
• Sheet number
The sheet number is assigned based on American system to indicate the exact area of the geography presented in the index chart because there are unrepeated numbers of sheets that consist of four Arabic numerals and one Roman numeral (I, II, III or IV) such as the scale map with 1:50,000 scale with 4 sheets as shown in the figure.
• Series number
The series number is used to indicate set number of the map; for example, there are several series numbers of Thailand, scale of 1:50,000 such as L708 that has the size of 10 x 15 minutes while the series number L7017 and L7018 is the map with 15x15 minutes size. This series number is fixed based on international American standard following the agreement of North Atlantic Treaty Organization (NATO). The series number L708 and L7017 have four components:
- L means a region in Asia, which is Thailand.
- 7 means fixed scale used with the scale from 1:70,000 to 1:35,000
- 0 means subparts of the region such as subparts of Thailand
- 8, 17 or 18 shows the number of edition
Therefore, Thai map therefore has the series number at L708 or L7017 that indicates component 1, 2 and 3 because it has the same scale. The component 4 is changed following the frequency of map making and the number is printed at the above right corner of the map.
• Index to adjoining sheet
The index to adjoining sheet is the contents presenting sheets spread in that sheet. It is convenient for searching for the next sheet or similar sheet; for example, sheet number 4746 I has surrounding sheets; the sheet contents is presented at the below right corner of the map as shown in the figure.
• Datum and Datum level
The datum and datum level presents the height of a specific position of sub-district such as vertical datum at mean sea level on Koh Lak Island, Prachuab Kirikhan province; horizontal datum at Indian datum 1975; the series of L7017 and L7018 is used as a reference based on World Geodetic System (WGS) 1984 of the United States of America.
• Declination diagram The declination figure presents three main north: true north, grid north and magnetic north.
- True north directing to the North Pole
- Grid north parallel directing to vertical grid
- Magnetic north directing to global magnetic field, in which there is unrepeated deviation each year
The declination figure indicates the annual north deviation value as shown in the figure. These three north does not have high level of deviation and may be overlaid when it is near the equator, and it may have high level of deviation if it is closed to the North Pole. The declination figure is shown at the below margin of the map.
The scale of map shows the comparative ratio between the distance measured on Map 1 and the true geographical distance. There are three methods presenting map ratio: bar scale also called graphic scale, representative fraction such as 1:50,000; verbal scale such as 1 centimeter on the map equals ½ kilometer in the true distance; the graphic scale or bar scale are in the form of straight lines controlled by values of distance on the global surface such as the scale of 1:50,000 means the same with the graphic and bar scales, in which each column has 2-centimeter width and representative fraction indicating in numbers such as 1:50,000 means 1 part of the map equals 50,000 parts on the global surface. The scale presents both representative fraction and graphic scale to benefit distance measurement and map areas. The graphic scale presents in both English and Metric System in the form of meter, yard, mile and sea mile as shown in the figure.
• Elevation Commonly, the map uses the scale of 1:50,000 presenting the distance of 20-meter contour line and 10-meter supplementary contour. The vertical evidence is mean sea level.
• Projection The projection presents the types of map projection such as a Transverse Mercator map projection between Latitude 84 degrees north and Latitude 80 degrees south
• Elevation Guide The evaluation guide presents the contour line characteristics and is presented in the square at below right corner of the map, in which there are shadow layers simply presenting differences towards the line as shown in the figure
• Latitude and Longitude The Latitude and Longitude presents the number of Latitude and Longitude of the map. It is presented at four corners of the map in minutes; for example, Chiang Mai map has series number L7017, sheet number 4746 I at between Latitude 19 degrees 15 minutes and 19 degrees 30 minutes and Longitude 98 degrees 45 minutes and 99 degrees 00 minute
• Grid The 1:50,000 scale map has intersected grid in the mall square shape. Each grid hasequal space with each other such as every 1,000 meters and there is grid number at the map border. These grids are useful to map orientation in details.
• User’s guide The user’s guide is at below right position of the map. If the map users find any mistakes or deviation on the map, please write a letter telling about the mistakes or deviation and send it to Royal Thai Survey Department, Bangkok 10200. The new map will be sent to you soon.
• Grid reference box The grid reference box presents the detailed positions; for example, the position reading methods to 100 meters are explained in the below square box by reading the large number of vertical grid at the left side and measure the distance (100 meters) from grid to the position such as 988 means vertical left grid that is 98 , so count to the right side to vertical grid 99. It can be divided into equal 10 small spaces. Then continue counting to the target position at space 8. It can be read as 8 and 773 means horizontal grid below the point that is 77. Continue counting to the horizontal grid 78 that is divided into 10 equal small space. Then count to the target position in space 3 that can be read as 3. Therefore, if we read the grid from 1,000 meters as shown in the figure elaborately to 100 meters, we will get the values of 988 and 773.
Symbols are marks or objects created to replace some details of geographical details or information presented on the map. The principle of cartographic symbolization emphasizes the symbols must be simple, clear and appropriate with map scale, ease to write and eases common people to understand without explanation. There are three features of the symbolization as follows:
• Physical features
The symbols created to symbolize natural things, not human’s creation:
- Water resource: river, canal, pond and basin
- Height of geographical surface: hill, mountain and plain
- Plants: types of forest
- Coast: cliff, gulf, beach, island and estuary
• Cultural features
The symbols created by human:
- Land usage: agricultural areas, mine and industrial areas
- Transportation: routes of cars, train, pathway, cart and plane
- Settlement: houses, villages, town, including buildings such as schools and temples
• Special features
- The symbols created to symbolize some special things the map makers want to present.
- It is used with specific or special maps such as soil map, forest map and geological map, etc.
• Map scale
In mapping, scale equals map scale, which means comparative scale between distance of two positions on the map and distance of two positions in true geography. The distance on the map is a unit.
Example: If the geographical map identifies map scale at 1:50,000 units in the true
geography and measuring unit is centimeter, 1-centimeter distance on the map symbolizes 50,000 centimeters length in the true geography.
- Types of Map Scale
In general, there are two types of map scales:
• Vertical scale
For example, the vertical scale is used in writing cross section or profile of geography
• Horizontal scale
For example, the horizontal scale is used to present details of objects horizontally or geographical map
• Scale calculation Actually, the map scale presented on the map to ease the users, but it is sometimes not shown. The map users therefore need to calculate the scale using these simple calculation methods:
- Comparison between distance on the map and true geography
Firstly, the users have to know the geographical areas for making the map; then observing the prominent position can be seen both on the map and true geography. After than measure the distance and compare them using the following equation:
Caution: Comparison between distance on the map and true geography must use the same measuring unit
Example: The distance between two positions on the map is 10 cm. and it equals 1,000 meters in the true geography
Scale calculation (Representative Fraction)
Map scale = 10 (centimeter) / 1,000 (meter)
= 10 (centimeter) / 1,000 x 100 (centimeter)
= 1: 10,000
Or the map verbal scale calculated from:
The distance on the map 10 centimeters equals the distance in the true geography = 1,000 meters
The distance on the map 1 centimeter equals the distance in the true geography = 1000/10
= 100 meters
Or written as 1 centimeter per 100 meters
- Comparing with other fixed scale maps
It means the map used for work does not have fixed scale. The scale calculation can be
done by comparing the map scales of two maps that covers the same area with known scale.
1) Select two clear prominent positions on both maps
2) Measure the distance between both positions on both maps
3) Use the distance measured on the map to calculate the distance in the true geography
4) Compare the distance measure on the map without fixed scale with the distance in the true geography measured in 3) to investigate the desired scale
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