introduction to field informatics chapter 1 remote sensing and geographic information system kyoto...

Introduction to Field InformaticsChapter 1

　 Remote Sensing and Geographic Information System

Kyoto University

Graduate school of informatics

Tetsuro SAKAI

1/30Copyright (C) 2010 Field Informatics Research Group. Kyoto University. All Rights Reserved.

An Overview of Remote Sensing

• Analyzed techniques of the characteristics and status of a target object without touching directly from the place left.

• Technical term was coined during the space age of the 1960s• Using the reflection and radiation of electromagnetic waves• Based on “All objects, if their types and environmental

conditions differ, have different characteristics in terms of the reflection or emission of electromagnetic waves.”

• Using magnetic or gravitational force instead of electromagnetic waves


Application field of a remote sensing

• Remote sensing, which covers wide-scale terrestrial, atmospheric and oceanographic data collection as well as the monitoring of global-scale environmental shifts, has applications for a wide variety of fields.

• In terrestrial science, it is used as a means of acquiring and analyzing data about the environment and natural resources; such as data on land use, land cover, changes in vegetation and projections of crop growth and grain harvests.

• In oceanography, it is used to measure sea level, water pollution, the distribution of plant plankton, sea temperature and so on

• In atmospheric science, it is used to examine the composition of minor atmospheric constituents, such as carbon dioxide and ozone, and to analyze cloud formations and other weather phenomena.

• In the global environment age, the importance of the remote sensing becomes increasingly big.


Conceptual diagram of remote sensing

Reflection of solar radiation

Thermal radiationReflection of microwave

　 Earth observation satellite

　

Visible spectrum/reflection infrared remote sensing: reflected sunlight

Thermal infrared remote sensing ： heat radiation

Microwave remote sensing ： reflection of emitted microwaves


Visible spectrum/reflection infrared remote sensing

Measuring reflected solar radiation (visible or infrared)

Observation is not possible at night or when clouds cover the sky

The peak of radiation of sunlight is a visible ray area.

Necessary to correct for atmospheric, topographical features and the position of the sun

Example of usageWeather observation satellite ： the distribution of the cloud and the water vapor, observation of snow ice and floating ice Earth observation satellite ： land coverage, land-use change, vegetation and mineral resource


Thermal infrared remote sensingMeasuring the thermal radiation which a target object emits

Temperature observation by measuring the thermal radiation

Human social economic activity observation by measurements of night-time artificial light

Observation of discharge of thunder

Example of usage

Measurement of sea water temperature: weather observation and the fishing industry

Observation in a hot spot :discovery of a brushfire and an accident

Observation of night-time artificial light ： grasp the extent of damage in areas hit by earthquakes and other disasters


Microwave remote sensingThe active method using Synthetic Aperture Radar (SAR).

A microwave is emitted and the reflective wave is observed, so it‘s also possible to observe in night.

A microwave which wavelength is long passes cloud, so corresponds to all-weather

A microwave have directionality, so undergoes influence of the topography hard

Example of usageTerrain analysis: the distortion of the topography by the crustal alteration

Land cover: the paddy area, rice growth process and vegetation


Spectral Reflection Characteristics

Shorter 　　　　　　　　　　　　　　　 Wave of length 　　　　　　　　　 Longer

B G R

Visible light

　Ultravio

let light

Plant

Soil

Water

Thermal radiation

Reflection of solar radiationS

trength

of the reflection

Stren

gth of th

e radiation

　

Near infrared 　　 Middle infrared 　　 Thermal infrared 　　　radiation 　　　　　 radiation 　　　　　 radiation 　

　

Microwave

Plant ： Reflection characteristic of chlorophyll, blue and red are absorbed, and green and near infrared are reflected.

Soil ： There is a reflective peak in a visible area.

Water ： reflect in the visible area, but absorb in the infrared area.


Wavelength range and Characteristic of Remote Sensing

　　　　　

　 Wave-class Name Wavelength Characteristics　 Visible Light Blue 0.4μm～ 0.5μm Distinction of the soil and the vegetation

　　 Green 0.5μm～ 0.6μm Vegetation activity

　　 Red 06μm～ 0.7μm Distinction of soil and water, vegetation activity

　 Infrared Rays Near-Infrared 0.7μm～ 1.3μmVegetation activity and distinction of land water and the topography

　　 SWIR 1.3μm～ 3μmJudgment of the inland water area, geological feature reading, soil moisture content

　　 Mid-infrared 3μm～ 8μm 　

　　 Thermal infrared8μm～ 14μm Temperature measurement

　　 Far infrared 14μm～ 1ｍｍ　　 Microwave X-band 2.4cm～ 3.75cm Reflect by leaves

　　 C-band 3.75cm～ 7.5cm Reflect by leaves and a branches

　　 L-band 15cm～ 30cmPenetrate through leaves, Reflect by trunks and the ground surface

　 * The name is different depending on the fields, and SWIR is sometimes included in Mid-infrared.

　　　　　　9/30Copyright (C) 2010 Field Informatics Research Group. Kyoto University. All Rights Reserved.

The process of image data processing

Ｚ

Atmospheric correction is influential correction of scattering in the atmosphere

• Corrections using values that reflection ratio is already known

• Performing comparative calculations between spectral bands 　

Geometric correction is the distortion of the sensor and correction of a map projection

• Comparing maps and images of the target area and designating several overlapping points

Topography correction is correction of difference in sunlight reflection in sloping ground

• Correction using the angle and inclination of the terrain and the position of the sun

• Ordinary method is ratio calculation between the band

Cla

ssifi

cati

on

p

rocessin

gC

orre

ctio

n

pro

cessin

g

Atmospheric correction

Geometric correction

Image classification

Topography correctionImage enhancement

and feature extraction


Classification processingImage enhancement and feature

extraction

• Color tone conversion and color composition using brightness histogram

• Spatial filtering• Spectral feature extraction (principal component analysis,

vegetation index,…)• Textural feature extraction 　Image classification

• Supervised classification (wealth previous information): Using data from selected training areas, the statistical values are calculated and the entire target area is classified. The maximum-likelihood classification method is generally used.

• Unsupervised classification ( little previous information): Using the variables of random sampling pixels, they are classified several classes by cluster analysis. Using these statistical values , the entire target area is classified.

Classification processing

Corre

ctio

n

pro

cessin

g

Atmospheric correction

Geometric correction

Image classification

Topography correction

Image enhancement and feature extraction


False-color and NDVI

False-color image NDVI image

Natural color ： Red, Green, Blue

False color ： NIR, Red, Green

Vegetation is shown to red

Normalized Difference Vegetation Index （ NDVI):-1 ～ +1NDVI = (NIR – RED)/(NIR + RED)NIR= the brightness value of the near infrared band.

The activity of the vegetation is so high

that the numerical value is big

Ikonos satellite image showing the Kyoto Prefectural Botanical Garden and the surrounding area 12/30Copyright (C) 2010 Field Informatics Research Group. Kyoto University. All Rights Reserved.

GIS: Geographic Information System

GIS is a system in which map information, along with various additional information, can be displayed and referenced using computers

Application fieldManagement of living infrastructure (house, road, water,…… ）Management of productive facility （ agricultural field, …. )

Management of a natural environment （ Forest, Park, watershed,... ）

Disaster prevention and military use…..

Four Ms plainly state the qualities of GIS Measurement of environmental variables Mapping of features Monitoring of environmental changes Modeling of plans or contingency plans


Concept of layers

• A layer is the unit of the data management in GIS

• Management by the respective layers every independent figure

• A conventional map condenses into 1sheet, GIS is made up of many separate sheets

• A layer is managed synthetically by position information

・・・・

RS classification

Aerial photography

ElevationDrainage systems

BuildingsTrain lines

Land use

Roads

Administrative boundary


Data Structures Concept

Polygon

Point

Line

Vector format data structureRaster format data structure

B 　　　Ｂ　　　 B 　　　Ｂ　　Ｂ　　B 　　　Ｂ　　ＢB 　　　Ｂ　　　 B 　　　Ｂ　　Ｂ　　B 　　　Ｂ　　ＢB 　　　Ｂ　　　Ａ　　　Ａ　　Ａ　　B 　　　Ｂ　　ＢB 　　　Ｂ　　　Ａ　　　Ａ　　Ａ　　B 　　　Ｂ　　Ｂ　B 　　　Ｂ　　　 B 　　　Ａ　　Ｂ　　B 　　　Ｂ　　ＢB 　　　Ｂ　　　 B 　　　Ｂ　　Ｂ　　B 　　　Ｂ　　Ｂ

A

B

The two representative data structures used in GIS are raster format and vector format. They have a merit and demerit respectively and are often combine used.

Express spatial information by a point, a line and a polygon

Express spatial information by grid


Acquisition of Positioning Information

There are two types of satellite positioning systems.GPS (Global Positioning System) is managed by the United States. GLONASS (Global Navigation Satellite System) is managed by Russia.GPS is widely generally used.

In order to handle space information in GIS, positioning information is needed

Until recently, positioning information was calculated on maps using a compass or measured from clearly-established locations (such as bridges, crossroads, benchmarks) on maps

Nowadays, with satellite positioning systems, such as GPS, positioning information has become much easier to obtain


Positioning Methods used in GPS

Single-point positioning Differential method Static method


Independent positioning method (Single-point positioning)

• Uses only one receiver

• Seeks the position of the observation point by measuring the false distance between that point and the positions of GPS.

• Four GPS satellites are necessary for correction of the receiver’s clock

• This method can position in real time, the accuracy of the measurements is comparatively low, with a margin of error of about ten meters.

Example of usage

• navigation

• simple surveying


Differential positioning MethodObservation at same time using multiple GPS receivers at the fixed benchmark position and at the measurement point.

Error information is calculated in benchmark point and the position is corrected using the error information.

At both measurement point, positional information is calculated with the same satellite

GPS with a differential function and the corrective information from such as the beacon bureau are needed. The error are about 1 m.

Example of usage

• Navigation support at neighboring seas and a harbor

• Simple measurement highly precise little


Static method positioning

Using two highly precise GPS receivers

The carrier phase of the GPS radio wave is measured and a base line vector between observation points is calculated.

Need time for observation and analysis, but the measurement precision is high. the error is several mm

Example of usage

• Highly precise control point surveying

• Scientific research activities such as measuring the movement of the earth’s crust


Processing of GIS

+

=

Overlaying

different themes layers are overlaid to create composite layers

A buffer

extracting target objects within a set radius from a specific point and line

• Data collection ： Collection of information in relation to the purpose of analysis

Existing and relevant resources, such as maps, statistical information and field reports

• Pre-processing and data input ： Task of inputting collected data into GISRequires the greatest expenditures of time and effort

• Database management ： Making and management of GIS databaseThe basis of the GIS software, the general user non-participate

• Information analysis processing ： Analysis operation to draw informationInformation retrieval, the making of the new layer, modeling

• Information output ： Final results of analysis are outputExample of information analysis


The standardization of and interrelation between data formats

related to spatial data

Standardization of the map information to support digital earth on the Internet

KML (Keyhole Markup Language)

Most GIS software

GPS

Google Earth

Google MapsNMEA, GPX

GML（ Geography Markup

Language ）Basis of description of

geographic information


Example of image transfer

Google Maps

　 Google Earth

　 GIS image

KML


Case Studies of RS and GIS Usage

Land coverage in a basin is analyzed using a satellite image by a ASTER sensor with TERRA satellite (resolution 15m).

Object place ： The Ishigaki-jima Island southern part

geometric correction

Land coverage classification

　

Satellite imageterrain map

basin

Land coverage figure of the basin unit

GIS


Geometric Correction

Yaeyama Islands

Raw image Image after geometric correction

Corrected using attached positional information for four corners and for the image's center

The upper left of the Figure is Iriomote Island and the upper right is a part of Ishigaki Island. This figures are rendered using false color. the blue areas are shallow seas and the red area are vegetation.


Classification

False-color image Image after unsupervised classification

Variables: the green band, red band, near-infrared band and the NDVI vegetation index.

Method of classification: Unsupervised classification(15classes)

Result ： Forest （ green ） , Farmland and a City area (pink color) , Coral reef and Sea (light blue )


Display in GIS with classification resultClassification result, map of Geographical Survey Institute and each basin layer are overlaid in GIS.


Land Cover Classification Result

Extraction of land cover classification result from drainage basin areas 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

Drainage basin A

Drainage basin B

Drainage basin A

Drainage basin B


Collection in a behavior track by GPS

　 The routes traveled by mountain climbers (original image by Yoshimura Tetsuhiko)

People visiting beauty spots including the national park increase, and natural destruction by the overuse is a problem

Visitor's behavior track is collected and the activities and frequency are analyzed.

A blue line and a red line in the figure indicate the difference of entrances and the thickness indicates a number of visitor.

Visitors are concentrating in a part of upper-right and lower-left in this figure.


3-S TechnologiesRemote sensing (RS)Geographical information systems (GIS) Satellite positioning systems (GPS)

The collecting and analysis of space information and their subsequent results are useful “tools”

The information system with space information is various - from the large-scale tasks of the earth level such as the climate change analysis, to the small-scale tasks of the local level such as a disaster prevention system or the environmental map

For the foreseeable future, the role of space information science, which brings real-world applications to geographic information, and the need for learning about the “3-S Technologies” are expected to continue to grow in importance.


introduction to field informatics chapter 1 remote sensing and geographic information system kyoto...

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