Topic 2 Portraying Earth Using Maps Remote Sensing

Topic 2: Portraying Earth: Using Maps, Remote Sensing and GIS l Introduction - to Maps: What is a Map? Benefits of Maps Marginal information on Maps Map Scale Map Projections: - Cylindrical Projections - Plane Projection - Conic Projection

Topic 2: Portraying Earth: Using Maps, Remote Sensing and GIS - Map Projections: - Equivalent Projection - Conformal Projection l Remote Sensing: - Aerial Photographs - Orthophoto Maps - Visible light & Infrared Sensing - Thermal Infrared Sensing - Microwave Sensing

Topic 2: Portraying Earth: Using Maps, Remote Sensing and GIS Remote Sensing: - Microwave Sensing - Multispectral Remote Sensing l Geographic Information Systems (GIS) - What is GIS - GIS Automation Tools l Isolines and Applications l

Introduction to Maps: What is a Map? l Geographic information describing earth’s surface features are often displayed by geographers on: - maps: examples include road map, topographic map, surveyor’s map, etc) - aerial photographs - satellite imageries - GIS, etc

Introduction to Maps: Benefits of Maps? l A map is a two-dimensional representation of the spatial distributions of features of interest in a place or region l Maps show spatial relationships between features, especially: - direction - distance - size and shape

Introduction to Maps: What is a Maps? May provide clue why things are located where they are l The main purpose of maps is to show the spatial distribution of one or more features of interest l

Orthophoto Map Topographic Map Geologic Map - Rock Types Road Map

Orthophoto Map from Aerial Photograph

USGS Topographic Map Quadrangle

Introduction to Maps: Benefits of Maps? l Benefits - of Maps: Map is the geographer’s most important tool Represents earth’s features on a flat paper it shows spatial relationships with great efficiency It can show true courses for navigation and true shapes of earth’s features

Introduction to Maps: Benefits of Maps? l Benefits - of Maps: It can be used to measure areas and distances It can be reproduced easily and inexpensively It is easier to handle and transport It is often smaller than the areas they represent and contains less details

Introduction to Maps: Benefits of Maps? l Benefits of Maps: - The accuracy and amount of information contained in a map will depend on its scale and projection l Disadvantages of Maps: - It distorts the earth in some ways, hence could not depict the earth with complete accuracy

Introduction to Maps: Benefits of Maps? l Disadvantages of Maps: - Map distortions become progressively pronounced as the part of the globe depicted gets larger

Introduction to Maps – Map Scale: l Scale is a mathematical expression or statement of a relationship between distances or sizes on map and their actual measurements on the ground l Types of scale: 1. Statement Scale or Verbal or Word Scale 2. Fractional Scale and 3. Graphical Scale

Types of Map Scale Three Types of Map Scale

Three Types of Map Scale

Introduction to Maps – Map Scale: l Statement Scale or Verbal or Word Scale A scale stating in words the distance on map compared to the actual distance on the ground Example: one inch on the map represents one mile on the ground or 1 inch = 1 mile) l Representative Fraction or Ratio Scale A scale in which map distance is represented as a proportional number of its actual distance on the ground

Introduction to Maps – Map Scale Example: 1: 63360 or 1/63360, meaning a unit length on the map equals 63360 units on the ground - Common Ratio Scales used on maps: a. world map (1: 264, 000) b. road map of a state (1: 1, 000 to 1: 2, 000) c. street map of a city (1: 10, 000) d. residential lot (1: 100)

Introduction to Maps – Map Scale l Graphical or Bar Scale: A scale shown as a line marked off in graduated distances

Introduction to Maps – Map Scale l Graphical or Bar Scale: A major advantage is that it remains valid when map is reduced into another size (through photocopying) because the graphical scale line and map size change in same dimension

Introduction to Maps – Large and Small Scale Maps l Two types of maps based on map scale are: - Small-Scale Maps - Large-Scale Maps l Small-scale maps show large portions of the earth cramped into a small paper l It is indicated by a map scale with a large denominator (1/1, 000) l Examples Map of small-scale maps: World map, US

Introduction to Maps – Large and Small Scale Maps

Introduction to Maps – Large and Small Scale Maps

Introduction to Maps – Large and Small Scale Maps l Large-scale maps show a very small area of the earth in a large space l It is indicated by a map scale with a small denominator (1/100) l Examples of large-scale maps: - a house plan - a school map

Different Scales: From Small To Large Scale Maps Small Scale Large Scale Map

Introduction to Maps – Large and Small Scale Maps l Class Practice Exercises: l convert a statement scale (1 inch = 2400 feet) to: - a fractional scale - a graphical scale l List three maps you consider to be a largescale map

Introduction to Maps: Marginal Information on Maps l Maps - are drawn for different purposes: general purpose maps (e. g. world map) thematic maps showing distribution of a specific phenomenon(population density) - In general, maps contain useful information to help in map interpretation - Most of such useful information are often shown on the margins of the map

Introduction to Maps: Marginal Information on Maps l Maps - are drawn for different purposes: general purpose maps (e. g. world map) thematic maps showing distribution of a specific phenomenon(population density) l In general, maps contain useful information to facilitate their use and interpretation l Most of such useful information are often shown on the margins of the map

Introduction to Maps: Marginal Information on Maps l Some - of these marginal information include: Map title Dates Legend Direction Scale Location Data Source Map projection, etc

Introduction to Maps: Marginal Information on Maps l Map - Title: It usually should reflect map content or purpose and identifies the area covered (e. g. Road Map of St. Louis) l Date: - Date of data collection and publication gives clear indication of how current or out-ofdate the information on the map is

Introduction to Maps: Marginal Information on Maps l Legend: - Often shown as a box explaining symbols used on the map - Symbols, colors, shadings used in representing features on the map explained l Direction: - Directions are indicated using geographic grids (e. g. latitude and longitude) and north pointing arrow

Introduction to Maps: Marginal Information on Maps l Direction: - The north arrow points at the Geographic (True) North Pole The Magnetic North Pole is the direction a magnetic compass points l Location: - Longitude and latitude coordinates are useful for locating places on maps

Introduction to Maps: Marginal Information on Maps l Map - - Scale: Gives the relationship between length measures on the map and the corresponding distance on the ground Map scale helpful when measuring distances between points or calculating the area occupied by any geographic feature on map

Introduction to Maps: Marginal Information on Maps l Data - - Source: Information on data source is important in establishing credibility of the final map It indicates the level of data quality and accuracy

Introduction to Maps: Map Projection l The Earth is spherical in shape as represented by the globe

Introduction to Maps: Map Projection l The globe accurately represents the shape of our planet l It is useful in maintaining the geometric relationships of: - longitudes to latitudes - equator to the poles - continents to oceans l It can also maintain correct: - comparative distances

Introduction to Maps: Map Projection l Without distortion, the globe can also maintain correct: - comparative sizes and - directions l But the globe has its own problems: - only half of the globe can be viewed at a time - only very little details can be displayed on a globe

Introduction to Maps: Map Projection l But the globe has its own problems: - globes are cumbersome to use and difficult to handle or carry around - computations on globe surfaces require complex and difficult equipment and techniques - globe construction is labor-intensive and costly

Introduction to Maps: Map Projection l In order to overcome some of the problems of working with the globe, flat maps are preferred because: - flat maps are portable - less expensive to reproduce - easy to work with l But this comes with some costs and disadvantages that include: - it may lead to geometric distortions

Introduction to Maps: Map Projection l But this comes with some costs and disadvantages that include: - violation of the continuity of the earth surface - distortion of reality - no true solutions to these problems hence all maps are not perfect

Introduction to Maps: Map Projection l Maps are flat whereas the Earth is spherical in shape l To produce a map, we need to transfer location information on spherical earth surface to their appropriate locations on a flat map

Introduction to Maps: Map Projection l The map projection process results in the distortion of four attributes of places on the globe: - distance between points place orientation or direction actual shape actual size (i. e. area)

Introduction to Maps: Map Projection The distortion problem progressively increases with the size of the globe being represented on a flat map l Common methods of map projections involves deliberate effort to preserve: - Conformal Projection (shape & direction preservation) - Equal-area or Equivalent Projection (size or area preservation) l

Preserves Area or Size Preserves Shapes

Map Projection - conformal projection l It distorts size but preserves shape (or orientation) l Angular relationships are maintained such that shape of any geographic feature is the same as observed on the spherical earth l Meridians and parallels cross at right angles

Map Projection - conformal projection Continued l Sizes of geographical features become progressively larger towards the higher latitudes (hence Greenland appears bigger than necessary) l A good example is the Mercator projection (directions remain constant and rectangular shape fits a flat map model

Map Projection - conformal & Equal Area projections

Map Projection - Equal-area projection l It preserves size but distorts shape and avoids misleading impressions of size l Great for showing distributions of geographic features l Shapes are sacrificed in order to maintain proper area relationships l Example: Lambert’s equal-area projection

Compromise Projections Map Projection l Not purely conformal nor purely equivalent l Robinson’s Projection is in this category and ensures accurate shape and scale (size) representation

Introduction to Maps: Map Projection l involves deliberate effort to preserve: - Compromise Projection (not truely conformal nor equivalent) l Preservation of one geometric property may lead to the distortion of another l Hence, not all distortions can be controlled on a single map

Compromise Projection Between Conformal and Equivalence

Map Projections: l Types of Map Projections: - Cylindrical Projections - Plane Projection - Conic Projection - Pseudocylindrical Projection type based on main source of light: - gnomonic projection (center light source) - orthographic projection (outside the earth) - stereographic projection (earth surface light)

Map Projections: Cylindrical Projection l It is produced by mathematically wrapping paper cylinder around the globe and touching the globe along the equator

Map Projections: Cylindrical Projection l This is called equatorial tangency which helps to produce: - right-angled grid network which become rectangular grids on flat maps - no distortions (e. g. size) along the circle of equatorial tangency - but distortion increases poleward, hence Greenland & Antarctica are larger than normal

Map Projections: Cylindrical Projection

Map Projections: Cylindrical Projection l Circle of tangency outside the equator are also used l Mercator projection is a good example of a cylindrical projection l Other examples of cylindrical projections: - Gall’s stereographic cylindrical projection - Lambert’s cylindrical Equal area Projection

Map Projections: Cylindrical Projection l Could show the map of the whole world but often cut off in the higher latitudes because of distortion issues

Map Projections: Cylindrical Projection l It preserves shapes (conformal) but distorts sizes on maps

Map Projections: Mercator Projection l Developed in 1569 and remains the most famous of all projections l Originally designed to facilitate navigation by sailors l It is a conformal projection, hence: - preserves shapes - size distortion increases rapidly poleward

Map Projections: Mercator Projection l It keeps the meridians parallel to one another instead of converging at the poles l This causes east-west stretching such that area or size is exaggerated by four times at lat. 60 o and thirty-six times at lat. 80 o l To maintain conformity, latitudes were spaced increasingly using mathematical formula to keep north-south stretching uniform

Map Projections: Mercator Projection It shows loxodrome or rhump line as straight line l A loxodrome is a straight line anywhere on a map and in any direction oblique to the grid lines and maintain a constant compass direction l Light source at the globe centre

Map Projections: Mercator Projection l Great Circle route on a spherical Earth surface

Map Projections: Mercator Projection l On Mercator Projection, the curved Great Circle approximated with four loxodromes

Map Projections: Plane Projection l It is also called azimuthal projection or zenith projection l It is a projection of the Earth on a flat paper placed on any point of the globe though polar tangency is common l Distortion l No increases away from point of tangency more than half of the globe can ne displayed

Map Projections: Plane Projection

Map Projections: Plane Projection Orthographic Plane Projection Showing Earth as it would appear from space

Map Projection – Conic Projection l It is a projection onto a cone surface with its apex placed above the pole

Map Projection – Conic Projection Latitudes are projected as concentric arcs of circles l Meridians are projected as straight lines radiating from the apex of the cone l

Map Projection – Conic Projection l Only one-fourth of Earth’s surface can be projected at a time l Best for mapping relatively small areas with great east-west extent l Useful for mapping the United States, China and other areas in the mid-latitudes

Map Projection – Conic Projection l Map distortion increases away from the apex of the cone Conic Projector

Map Projection – Pseudocylindrical Projection l It is also called: - elliptical projection - oval projection l Used in mapping the entire globe l But smaller areas could be mapped if located at the central parallel meeting the central meridian with the least distortion

Map Projection – Pseudocylindrical Projection l Final maps look oval in shape and meridians converge at the pole l The meridians are curved except for the central meridian that drawn as straight line l Goode’s interrupted homolosine projection is a good example l It is equivalent projection

Map Projection – Pseudocylindrical Projection l But also maintains the shapes of continental coastlines Projection is interrupted in the oceans to greatly reduce shape and size distortions l It distorts shapes of areas in the high latitudes l l Hence, Goode splits his map in the southern oceans at selected meridians

Isolines l Isolines are lines joining places of equal values l There are many types of Isolines: - Isobar: Line joining places with the same pressure value or line of constant pressure Isotherm: Line joining places with the same temperature value or line of constant temperature Isoamplitude: Line joining places with the same wave amplitude or line of constant wave amplitude

Isolines - Isohyet: Line joining places with the same rain fall value or line of rain

Isolines

Isolines

Isolines l Isoline joining places of the same elevation is called contour line l Very closely spaced contours represent steeper terrains l Widely spaced contours represent gentle to flat terrains

GPS: Global Positioning System l GPS is global navigational satellite system for determining the location of a place l Developed in the 1970 s and 1980 s by the US DOD and once called NAVSTAR GPS (Navigation Signal Timing and Ranging GPS) l It consists of at least 24 high-altitude satellites with a minimum of four to six in view at any location

GPS: Global Positioning System

GPS: Global Positioning System l GPS accuracy may fall within ± 15 meters l Wide Area Augmentation System (WAAS) has significantly improved GPS accuracy to ± 3 meters l WAAS ground-based stations monitor satellite signals & generate correction signal to GPS units. l NOAA Continuously Operating GPS Reference Stations (CORS) detect location changes of <1 cm

GPS: Global Positioning System l GPS - applications include: earthquake forecasting ocean floor mapping and mapping in general volcanic monitoring data collection and damage assessment navigation GPS in vehicles military uses, etc

Remote Sensing: Introduction l Remote sensing is the collection of data about an object by a device not in direct contact with the object l Common - types of remote sensing include: Aerial photographs Orthophoto maps Visible light and Infrared (IR) Scanning Thermal IR scanning Radar and Sonar, etc

Remote Sensing: Introduction l Remote sensing originally involved the use of airplanes but today 100 s of satellites are used l Satellites in low orbits of less than 20, 000 km orbit the earth taking photographs l Satellites on geosynchronous orbit (36, 000 km) remain in one spot to gather data

Remote Sensing: Aerial Photography l Aerial photograph taken for some height above the ground using: - balloons (France 1858 & USA 1860) - airplane (as from WW 1 1914 -1918) - rockets l Based on camera angle, aerial photographs are classified as: - vertical (great for precise measurement) - oblique (measurement is more difficult)

Remote Sensing: Aerial Photography

Remote Sensing: Orthophoto Maps l Orthophoto maps are derived from aerial photographs and images l Distortions caused by camera tilt and difference in ground elevation are removed l Shows landscapes in greater details, multicolored; and great for showing low-lying areas l Georeferenced; distance measurement is possible

ORTHOPHOTO MAP

Remote Sensing: Visible Light & Infrared l Uses cameras with films sensitive to the visible light or Infrared portions of the electromagnetic spectrum

Remote Sensing: Visible Light and Infrared Sensing l Conventional photographic films were only sensitive to visible light but other wavelengths could produce more information omitted by visible light l During WWII Infrared sensing using electronic sensors or films sensitive to near infrared wavelength was introduced

Remote Sensing: Visible Light and Infrared Sensing l IR imagery produces false-color images such that: - healthy vegetation is red - bare ground is gray-blue l IR imagery is useful for the identification and evaluation of vegetation

Remote Sensing: Thermal Infrared Sensing? l Involves the use of middle or far infrared portion of the spectrum called thermal IR l Useful for sensing: - temperature of objects - forest fires - weather parameters (e. g. GOES Weather satellites)

Remote Sensing: Multispectral Remote Sensing l Involves multiband sensing l Satellites equipped with instruments imaging at several regions of the electromagnetic spectrum simultaneously

Remote Sensing: Multispectral Remote Sensing l Examples of multispectral Sensing systems: - Landsat - SPOT - IRIS l Landsat: - launched a four-band multispectral Scanning System (MSS) with a scene of 115 by 106 miles

Remote Sensing: Multispectral Remote Sensing l Landsat: - launched Landsat 4 and 5 in early 1980 s with seven-band Thematic Mapper (TM) of 30 m by 30 m pixels - Launched Landsat 7 in 1999 with eight-band Enhanced Thematic Mapper plus (ETM+)

Remote Sensing: Multispectral Remote Sensing

Remote Sensing: Multispectral Remote Sensing

Geographical Information System (GIS) l It is a database management system that facilitates the collection, analysis and display of geographic data l Owes its origin to a group of new computerbased technologies developed in surveying, photogrammetry, cartography, spatial statistics, and remote sensing l It has the ability to accept digital satellite imageries and other data sources

Geographical Information System (GIS) l It stores the geo-referenced data and integrates multi-layers of attributes of a place into a single usable map l GIS accepts both raster-based (rectangular grid cells) and vectorbased (points, lines or polygon) data l It could be used to analyze both environmental and social processes

REVIEW QUESTIONS FOR TOPIC 2 1) A map scale which says “ 1 in. = 21 mi” is a A. divisional map scale. B. fractional map scale. C. graphic map scale. D. verbal map scale. E. orthonormal map scale.

1) A map scale which says “ 1 in. = 21 mi” is a A. divisional map scale. B. fractional map scale. C. graphic map scale. D. verbal map scale. E. orthonormal map scale. Figure 2 -4 Explanation: A verbal map scale tells you, with words, what the between area on the map and area on Earth is.

2) _______ are automated systems for the capture, storage, retrieval, analysis, and display of spatially referenced data. A. Cartography B. Geographic Information systems C. Remote Sensing D. Global positioning systems E. Geomatic engineering Figure 2 -29

2) _______ are automated systems for the capture, storage, retrieval, analysis, and display of spatially referenced data. A. Cartography B. Geographic Information systems C. Remote Sensing D. Global positioning systems E. Geomatic engineering Figure 2 -29 Explanation: By definition, geographic information systems are systems which store, retrieve, analyze, and display spatial data.

3) Radar systems use radio waves as a means for remote sensing. Radio waves are shorter than which of these waves in the electromagnetic spectrum? A. Microwaves B. X-rays C. Visible waves D. Infrared waves E. Radio waves are the longest waves

3) Radar systems use radio waves as a means for remote sensing. Radio waves are shorter than which of these waves in the electromagnetic spectrum? A. Microwaves B. X-rays C. Visible waves D. Infrared waves E. Radio waves are the longest waves Figure 2 -22 Explanation: On the electromagnetic spectrum (Figure 222), radio waves have the longest wavelengths of all types of

4) Isoline is a generic term that refers to lines joining places of equal value or something. Isolines joining places of equal elevation are known as A. isotherms. B. isobars. C. isohyets. D. contour lines. E. isogonic lines. Figure 2 -15

4) Isoline is a generic term that refers to lines joining places of equal value or something. Isolines joining places of equal elevation are known as A. isotherms. B. isobars. C. isohyets. D. contour lines. E. isogonic lines. Figure 2 -15 Explanation: By definition, the lines of constant elevation on a elevation map are called contour lines.

5) Map projections that preserve the correct shapes of places and compromise area are known as A. conformal. B. equivalent. C. cylindrical. D. Mercator. E. isotropic. Figure 2 -7

5) Map projections that preserve the correct shapes of places and compromise area are known as A. conformal. B. equivalent. C. cylindrical. D. Mercator. E. isotropic. Figure 2 -7 Explanation: A map projection that maintains the correct shapes of geographic locations in exchange for preserving their size is called a conformal map projection.

6) Globes are less frequently used than maps except for classroom purposes. This is because globes A. are illegible compared to maps. B. are hard to read. C. are cumbersome. D. do not maintain the correct geometric relationship between locations. E. are inaccurate when compared to maps. Figure 2 -6

6) Globes are less frequently used than maps except for classroom purposes. This is because globes A. are illegible compared to maps. B. are hard to read. C. are cumbersome. D. do not maintain the correct geometric relationship between locations. E. are inaccurate when compared to maps. Figure 2 -6 Explanation: Globes have many advantages and disadvantages. They maintain the correct geometric locations of places on Earth, but are large and bulky, making them inconvenient for settings outside of a classroom.

7) Which of the following is not an example of a remote sensing system? A. Satellites B. Radar C. Global positioning system D. Aerial photography E. Lambert-conformal maps

7) Which of the following is not an example of a remote sensing system? A. Satellites B. Radar C. Global positioning system D. Aerial photography E. Lambert-conformal maps Explanation: Lambert-conformal maps are a special type of conformal map projection. As a result, they are not a type of remote sensing system.

8) The map legend tells you A. the history of the map. B. what direction is north. C. the map projection. D. how to interpret the map. E. latitude and longitude.

8) The map legend tells you A. the history of the map. B. what direction is north. C. the map projection. D. how to interpret the map. E. latitude and longitude. Figure 2 -5 Explanation: Maps have many different components. The map legend gives you information about how to interpret colors, shapes, locations, etc. on a map.

9) Maps nearly always have a special purpose. This purpose is to A. show the exact size and height of physical features. B. represent an enlargement of a section of Earth. C. resolve misunderstandings regarding positional relationships on Earth’s surface. D. show as much spatial information as the paper can possibly hold. E. show the distribution of selected phenomena. Figure 2 -2 b

9) Maps nearly always have a special purpose. This purpose is to A. show the exact size and height of physical features. B. represent an enlargement of a section of Earth. C. resolve misunderstandings regarding positional relationships on Earth’s surface. D. show as much spatial information as the paper can possibly hold. Figure 2 -2 b E. show the distribution of selected phenomena. Explanation: A map’s purpose is to provide a spatial distribution of desired phenomena.

10) The global positioning system (GPS) A. uses satellite measurements to provide navigation on Earth’s surface. B. is based off of radar. C. only works in urban areas. D. provides location based on miles from a major city. E. allows for the layering of maps on each other.

10) The global positioning system (GPS) A. uses satellite measurements to provide navigation on Earth’s surface. B. is based off of radar. C. only works in urban areas. D. provides location based on miles from a major city. E. allows for the layering of maps on each other. Figure 2 -19 Explanation: The GPS system is a remote sensing system that is used to identify locations on Earth based on latitude and longitude.