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Remote Sensing the Urban Landscape

Urban landscape are composed of a diverse assemblage of materials (concrete, asphalt, metal, plastic, shingles, glass, water, grass, shrubbery, trees, and soil) arranged by humans in complex ways to build housing, transportation, utilities, commercial and industrial facilities, and recreational landscape.

Remote Sensing data collection and processing provide basic human spatial services for urban studies and applications.

• City, county, and regional councils of government which legislate zoning regulations to hopefully improve the quality of life in the urbanized areas

• City and state departments of commerce which are mandated to stimulate development, often to increase the tax base

• Tax assessor offices which maintain legal geographic descriptions of every parcel of land, assess its value

• County and state departments of transportation that maintain existing facilities, build new facilities, and prepare future transportation demand

• Public and private utility companies (water, sewer, gas, electricity, telephone, cable) to plan and provide the most efficient cost-effective services

• Departments of parks, recreation, and tourism to improve facilities• Departments of emergency management for mitigating destruction and

allocating resources in the event of a disaster• Private real estate companies which are paid to find the ideal location

for industrial, commercial, and residential development• Developers who continually build residential, commercial, and industrial

facilities to stay business.

Detailed urban land information is required by:

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Chlorine gasChlorine gas

Disasters Requiring Immediate Emergency Response

Mudslide Mudslide

Disasters Requiring Immediate Emergency Response

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Disasters Requiring Immediate Emergency Response

On December 24, 2004, tsunami swept across the Indian Ocean, spawned by a magnitude 9.0 earthquake off the coast of Sumatra.

The Indonesia province of Aceh was hit the hardest by the earthquake and tsunamis.

The IKONOS images show that the town of Lhokngawas completely destroyed.

Disasters Requiring Immediate Emergency Response

On December 24, 2004, tsunami swept across the Indian Ocean, spawned by a magnitude 9.0 earthquake off the coast of Sumatra.

Aside from Indonesia, the island nation of Sri Lanka likely suffered the most casualties.

The QuickBird image acquired on December 26, 2009 illustrates that the water is flowing out of the inundated area and back to ocean, creating turbulence offshore.

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Disasters Requiring Immediate Emergency Response

On April 6, 2009 (yesterday), a magnitude 6.3 earthquake hit central Italy.

The SRTM image illustrate the topography of the central Apennine Mountains and the faults along which the earthquake occurred.

Disasters Requiring Immediate Emergency Response

On May 12, 2008, a magnitude 8.0 earthquake hit Wenchun, China (the 19th

deadliest earthquake of all time).

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Temporal and Spatial Characteristics of Urban Attributes and Remote Sensing Systems

•• There are a number of remote sensing systems that currently There are a number of remote sensing systems that currently provide provide somesome of the desired urban/socioof the desired urban/socio--economic information economic information when the spatial resolution required is poorer than 5 x 5 m and when the spatial resolution required is poorer than 5 x 5 m and the the temporal resolution is between 1 and 55 days.temporal resolution is between 1 and 55 days.

•• Very high spatial resolution data (<1 x 1 m) is required to satVery high spatial resolution data (<1 x 1 m) is required to satisfy isfy many of the sociomany of the socio--economic data requirements.economic data requirements.

USGS (Anderson) Classification System

1 Urban or Built-up11 Residential

111 Single-Family Residential1111 House, houseboat, hut, tent1112 Mobile home

112 Multiple-Family Residential1121 Duplex1122 Triplex1123 Apartment Complex or Condominium1124 Mobile home (trailer) park

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Urban/Suburban Applications and the Minimum Resolutions Required

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Urban/Suburban Applications and the Minimum Resolutions Required

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Clear polygons represent the spatial and temporal characteristics of selected urban attributes

Gray boxes depict the spatial and temporal characteristics of the remote sensing systems that may be used to extract the required urban information

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Urban/Suburban Spectral Resolution Considerations

USGS Level III land-cover is best acquired using the visible (0.4 -0.7 µm), near IR (0.7 - 1.1 µm), middle-IR (1.5 - 2.5 µm), and/or panchromatic (0.5 - 0.7 µm) portions of the spectrum.

Building perimeter, area, and height information is best acquired using black-and-white panchromatic (0.5 - 0.7 µm) or color imagery (0.4 - 0.7 µm).

TIR (3 - 12 µm) information may be used to obtain urban temperature measurements and study the effects of urban heat island.

QuickBird satellite image0.6-m spatial resolution

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QuickBird satellite image2.5-m spatial resolution

Urban/Suburban Spatial Resolution Considerations

Generally, the higher the spatial resolution of remote sensing data, the more detailed information that can be extracted in the urbanenvironment.

But how do we know what spatial resolution imagery to use for a specific urban application? Some references are available.

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Nominal Spatial Resolution (Ground-Resolved Distance)

Rule: There needs to be a minimum of four spatial observations (e.g., pixels) within an urban object to identify it. Or, the sensor spatial resolution should be one-half the width of the smallest object of interest.

For example, to identify mobile homes that are 5 meters wide, the minimum spatial resolution is less than 2.5 x 2.5 m pixels.

Stages of Development:• Original state• Partial or

complete clearing

• Land subdivision

• Roads• Buildings• Landscaping

Urban/Suburban Temporal Resolution Considerations

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Stages of Development:• Original state• Partial or

complete clearing

• Land subdivision

• Roads• Buildings• Landscaping

Urban/Suburban Temporal Resolution Considerations

Residential Land Use

Prior to investigating how residential land use appears on remotely sensed data, it is important to introduce the concept of Form and Function. Basically, the function of a building often dictates its form.

For example, the need to house a single family often results in the creation of a detached dwelling composed of several attached rooms.

Quality of Life Indicator

A research topic.

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Single Family Residential

Multiple-family Residential

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Transportation Infrastructure

Temporal Temporal Spatial Spatial Resolution Resolution ResolutionResolution

T1 T1 -- general road centerlinegeneral road centerline 1 1 -- 5 years 1 5 years 1 -- 30 m30 mT2 T2 -- precise road widthprecise road width 1 1 -- 2 years 0.25 2 years 0.25 -- 0.5 m 0.5 m T3 T3 -- traffic count studies 5 traffic count studies 5 -- 10 min 0.25 10 min 0.25 -- 0.5 m0.5 mT4 T4 -- parking studiesparking studies 10 10 -- 60 min 0.25 60 min 0.25 -- 0.5 m0.5 m

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The Dalton Highway and Trans-Alaska-Pipeline

Commercial and Services

An extended USGS land-use and land-cover classification system represents a common-sense hierarchical system that can be aggregated back to level I and II.

1. Central Business District2. Automotive and Boat3. Department Stores4. Finance and Construction5. Food and Drug6. Funeral and Cemetery7. House and Garden8. Recreation9. Warehousing/Shipping10. Public Buildings and Facilities (administration, fire, police, postal, libraries... 11. Education12. Medical ….

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Commercial and Services

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Recreation

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RecreationRecreation

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Industrial Land Use

Industries often have unique assemblages of raw materials, equipment, final products and waste, as well as buildings that characterize the industry.

1. Mechanical-processing Industries2. Chemical-processing Industries3. Heat-processing Industries4. Transportation Infrastructure5. Communications and Utilities….

Processing: ChemicalProcessing: Chemical

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Processing: Mechanical

Industry: Extractive

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Socioeconomic Characteristics

Population Estimations

Energy Demand and Conservation

Quality of Life IndicatorsBuildingLotAdjacent AmenitiesAdjacent Hazards

Population estimation can be performed at the local, regional, and national level based on:

• counts of individual dwelling units,

• measurement of land areas, and

• land use classification.

Remote Sensing Assisted Population Estimation

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Dwelling Unit Estimation Technique Assumptions:

• imagery must be of sufficient spatial resolution (0.3 - 5 m) to identify individual structures even through tree cover and whether they are residential, commercial, or industrial buildings;

• some estimate of the average number of persons per dwelling unit must be available, and

• it is assumed all dwelling units are occupied.

Urban/surburban attributes that may be extracted from remote sensor data and used to assess housing quality and/or quality of life

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Impervious Surface: is defined as any impenetrable material that prevents infiltration of water into the soil.

RooftopsRoads Sidewalks Parking lots Driveways Other manmade concrete surfaces……

Impervious surface has been identified as a key environmental indicator due to its impacts on water systems and its role in transportation and concentration of pollutants.

Studies about the relationship between ISA and watershed suggested that:

< 10% slightly impacted10%-25% water quality is impacted> 25% water quality is degraded

Environmental Impact of Impervious Surface Areas

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Methods for Extraction of Impervious Surface Areas

1. Manual delineation through aerial photography

2. Classification of middle resolution remote sensing data

3. Sub-pixel methods

4. Estimation from land-use and land-cover data and impervious surface coefficient

5. ISA extraction from high spatial resolution remote sensing data

Comparison of Orthophotos and QuickBird-2 images

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Extracted impervious surface areas from orthophotos (top) and QuickBird-2 (bottom)

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The result indicates that 10.3% of the state land are covered by the ISA. …Only sixteen towns in the state have ISA cover less than 10%.….

ISA

Non-ISA