Title:Introduction to Visual Image Interpretation, Chapter 4, Remote Sensing and Image Interpretation
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E.g., urban use, residential use, or single-family housing. ... This removes red and similarly blue from white light, giving green color of leaves. ... – PowerPoint PPT presentation
Title: Introduction to Visual Image Interpretation, Chapter 4, Remote Sensing and Image Interpretation
1 Introduction to Visual Image Interpretation Chapter 4 Remote Sensing and Image Interpretation (Mercury Topography--Smithsonian) 2 Table of Contents
Land Use
Geologic Mapping
Sedimentary Rocks
Fractures and Faults
Landform Identification and Evaluation
Vegetation Indices
Agriculture Applications
Forestry Applications
Range-land Applications
Fluvial Erosion Deposition
Water Resource Applications
Environmental Assessment
Flood Damage Estimation
3 Land Use/Land Cover Mapping
Knowledge of land use and land cover important for planning and management activities.
Land cover maps being developed from local to national to global scales.
Panchromatic medium-scale aerial photographs to map land use has been the acceptable way since 1940s.
More recently small-scale aerial photographs and satellite images have been used for land use/land cover mapping.
Land cover terminology relates to the type of feature present on Earths surface.
Corn fields lakes maple trees etc
Land use relates to human activity.
E.g. urban use residential use or single-family housing.
Knowledge of both land use and land cover can be important.
USGS devised land use and land cover classification system for use with remote sensor data in mid-1970s.
4 USGS Land Use / Land Cover Example
Classification System listed on page 210 (Level 1 and Level 2).
21 - Cropland and pasture
43 - Mixed forest land
61 - forested wetlands
(USGS) 5 High-Resolution Land Use and Land Cover mapping
Left side - 1996
Right side 2050 (predicted).
Albuquerque NM 6 Geologic and Soil Mapping
Earth has a highly complex and variable surface.
Topographic relief and material composition follow the geology underlie each part of the surface.
Type of rock fractures erosion depositional features etc bear imprint of processes that produced them.
Persons seeking to understand and explain Earth materials must be able to recognize surface expressions of various materials and structures.
Visual image interpretation and geologic and soil mapping allow materials and structures to be identified and evaluated.
Geologic and soil mapping will always require a considerable amount of surface field exploration.
However mapping process can be greatly facilitated through the use of image interpretation.
7 Geologic Mapping
First aerial photographs for geologic mapping purposes taken in 1913 (Bengasi Libya).
Earliest uses of air photos were for geologic data base map compilation -- especially for petroleum exploration.
Some interpretive uses of aerial photographs date back to the 1920s.
Widespread use of air photos for geologic mapping and evaluation began in the 1940s.
Geologic mapping involves the identification of landforms rock types and rock structures (folds faults and fractures).
Much information about potential areas for mineral exploration can be provided by interpretation of surface features on aerial photographs and satellite images.
8 Geologic Applications
Remote sensing useful for
Mapping rock units (stratigraphy).
Studying the expression and modes of the origins of landforms (geomorphology).
Determining the structural arrangements of disturbed strata such as folds and faults (structural geology).
Evaluating dynamic changes from natural events e.g. floods volcanic eruptions earthquakes (hazards).
Seeking surface clues such as alteration and other signs of mineralization to subsurface deposits of ore minerals oil and gas and groundwater.
9 Sedimentary Rocks
There are three general types of rock
Sedimentary rocks most common and extend over 75 of lands surface.
Igneous rocks extend over 20 of lands surface.
Metamorphic rocks extend over about 5.
Sandstone shale and limestone are principal sedimentary rocks that are considered.
Sedimentary rocks formed by consolidation of layers of sediments that have settled out of water or air.
Clastic sediments are converted into coherent rock masses by lithification a process which involves cementation and compaction by weight of overlying sediments.
Nature of constituent particles and way in which they are bonded determine texture permeability and strength strength of the rocks.
10 Sedimentary Rocks (Continued)
Sedimentary rocks containing primarily sand-sized particles are called sandstone.
Those containing primarily silt-sized particles are called siltstone.
Those containing primarily clay-sized particles are called shale.
Limestone has high calcium carbonate content and is formed from chemical or biochemical action.
Chemical precipitation of mostly calcium carbonate (CaCO3) from water.
Biochemical processes acting on shells shell fragments and plant materials.
Clastic deposition of shell material as marine or lacustrine environment.
Principal sedimentary rock characteristics that affect appearance on aerial and space images are bedding jointing and resistance to erosion i.e. resistant cliff forming strata.
11 Sedimentary Rocks (Continued)
Sedimentary rocks are mostly stratified or layered.
Individual layers called beds.
Top and bottom of each bed have more or less distinct surfaces called bedding planes that terminate one bed and begin another i.e. unconformities.
Individual beds have somewhat different characteristics.
Thickness varies from few millimeters to hundreds of meters
Usually start off nearly horizontal but may tilt due to movements of earths crust i.e. tectonic activity.
Joints are cracks through solid bodies of rocks that that have little or no movement parallel to joint surfaces.
Primarily perpendicular to bedding planes
May intersect other joint planes
Several systematic joints constitute joint set and two or more sets in a recognized area form a joint system
Streams often follow joint lines moving from one to another.
12 Sedimentary Rocks (Continued)
Resistance to erosion depends on rock strength permeability and solubility.
Rock strength a function of bonding agent
Thick beds of sandstone bonded by quartz (ortho-quartzite) are very strong and may be used as building material.
Thin beds of shale are very weak.
Permeability refers to ability of rock to transmit water and depends on pore spaces between sediment particles.
Sandstone generally very permeable can be an aquifer.
Shale is usually very impermeable can be an aquaclude.
Limestones are soluble in water over thousands of years especially if carbonic acid present e.g. karst topography.
13 Sedimentary Rocks (Continued)
Sandstone
Bedding often prominent on images especially when occurring over softer more easily eroded formations such as shale.
Jointing is prominent with joint system consisting of two or three dominant directions.
Resistance to erosion varies depending on strength of cementing agent.
Cemented with iron compounds and silica typically strong e.g. ironstone concretions.
Cemented with carbonates weaker.
Very permeable with rainfall percolating downward through rock rather than becoming erosion-producing surface runoff.
Percolating water can dissolve carbonate cementing agent.
14 Fractures and Faults
A fracture (or joint) is a crack or break in the rock in which either side springs apart by a small distance.
Seen from a distance as linear mark in which tone is same on each side.
A fault is a break in which the rock on one side s or slips against the rock on the other side so that each is displaced by some distance.
Sharp discontinuity in tonal pattern is a distinct possibility.
(rst) 15 Morro Bay Imagery (rst) h-Morro Rock 16 Histogram from Morro Bay Imagery
Big return at 12 due to ocean
Returns around 28 from land
(Remote Sensing Tutorial) 17 Finding Oil
Case study by Eason Oil and Earth Satellite Corps
Landsat imagery examined in areas that have established petroleum reserves.
Telltale surface indications
Standard-processed and computer-enhanced data.
Areas selected in which the surface does not give clear indication of subsurface conditions.
If imagery identified hydrocarbons under difficult conditions Landsat would increase in stature as an oil/gas discriminator.
Andarko Basin of south-central Oklahoma selected.
Basin or down-sag in crust allowed sedimentary rock to accumulate.
Oil and gas present in structural and stratigraphic traps.
18 Finding Oil Continued (rst)
Surface expressions in basin meager.
Investigators focused on undiscovered fractures and subtle chemical alterations.
Results inconclusive and discouraging.
19 Elements of Image Interpretation for Landform Identification and Evaluation
Systematic observation and evaluation of key elements studied stereoscopically
Topography
Drainage pattern and texture
Erosion
Image Tone
Vegetation
Land use
20 Topography
Each landform and bedrock type has own topographic form
Typical size and shape
Change at boundary between two different landforms
Vertical photographs with normal 60 overlap appear exaggerated in height by three to four times for most individuals.
Slopes appear steeper than they are
Specific amount of vertical exaggeration observed in stereopair is a function of geometric conditions under which photographs are viewed and taken.
21 Stereo to Topography Methodology from Smithsonian (Lunar Crater Topography) 22 Vegetation and Land Use
Differences in natural or cultivated vegetation often indicate differences in terrain conditions some examples
Orchards and vineyards normally located on well-drained soils.
Truck farming takes place on highly organic soil with perhaps large peat deposits.
In other cases vegetation and land use can obscure differences in terrain conditions.
23 Soil Mapping
Employed heavily in comprehensive land use planning.
Must be premised on thorough inventory of natural resource base.
Detailed soil surveys are the product of intensive study of soil resources by trained scientists.
Air photo interpretation has been heavily coupled with extensive field work.
Soil scientists traverse landscape on foot identify soils and delineate soil boundaries.
Relationships of soils to vegetation geologic parent material landform and landscape position are evaluated.
Air photo interpretation has been used since early 1930s to facilitate the soil mapping process.
USDA has been preparing soil survey maps since about 1900.
Most soil surveys since 1957 have contained soil maps on photomosaic base at a scale of 124000 120000 or 115840.
24 Agriculture Applications and Crop Management Information
Pre-planting variations studied in surface moisture texture and organic content.
Plowing / Planting progress determined drainage runoff and erosion.
Emergence time delayed emergence detected such as low plant density insect disease or weather problems.
Mid-growing season observed damage due to adverse moisture misapplication of chemicals insects diseases eroded top soil.
Pre-harvest stand condition checked acreage to be harvested significant weed invasion.
Post-harvest area determined to be harvested weed and volunteer re-growth erosion and soil moisture problems.
25 Vegetation Indices
Spectral bands can be combined to accentuate vegetated areas.
Ratio Vegetation Index (RVI) is ratio of sensed radiation bands.
RVI NIR / Red
Vegetation has high NIR (Near Infrared) return and low red return.
(Virtual Science Centre) 26 Normalized Difference Vegetation Index (NDVI)
NDVI (NIR - Red) / (NIR Red)
NDVI band combined with other bands to form color composite.
Many sensors operate in green red and near IR (NIR) regions.
Vegetation radiation absorption and reflectance discriminated.
Absorption centered at 0.65 m (visible red) by chlorophyll pigment.
This removes red and similarly blue from white light giving green color of leaves.
Strong reflectance between 0.7 and 1.0 m NIR band.
Tonal signatures on multispectral images distinct.
Darker tones in blue
Darker tones especially in red
Somewhat lighter in green
Notably lighter in near IR.
28 Vegetation Applications Continued (rst) 29 Landsat Vegetation Application (rst) 30 Principles of Landform Identification and Evaluation
Various terrain characteristics important to soil scientists geologists geographers civil engineers urban and regional planners landscape architects real estate developers and others.
Numerous terrain characteristics can be estimated by means of visual image interpretation such as
Bedrock type
Landform
Soil texture
Site drainage conditions
Susceptibility to flooding
Depth of unconsolidated materials over bedrock
31 Forestry Applications
Growing challenges exist with management of forests for wood forage water wildlife and recreation.
Special concerns with timber management maintenance and improvement of existing stands.
These cover nearly one-third of worlds land area.
distributed unevenly with widely varying value.
Visual image interpretation used to monitor many of worlds forest conditions.
Trees identified on aerial and satellite images through process of elimination.
Species eliminated which are impossible or improbable because of location physiography or climate.
Groups of species identified in area.
Identify individual tree species using basic image interpretation principles such as
Shape size pattern shadow tone texture.
32 Vegetation and Deforestation
AVHRR Index
Europe probably most vegetated.
South America next in vegetation.
Australia least vegetated.
33 Vegetation and Deforestation
Farmlands/open area in black.
200000 out of 1.9 million square miles cleared.
Public outcry slowing removal.
Brazilian Amazon Deforestation
Rain forests in blue/purple.
Woodlands in green/yellow.
34 Range-land Applications
Range-land defined as predominantly grasses grass-like plants or shrubs.
Animal grazing important influence in pre-civilization state
Potential land use as agriculture recreation or housing
Range-land management utilizes science and experience for protection improvement and continued welfare of basic range-land resources.
Soils
Vegetation
Endangered plants and animals
Wilderness water and historical sites
Emphasis placed on the following (table 4.14 page 247).
Suitability of vegetation for multiple uses
Design and implementation of vegetation improvements
Implications of social and economic effects of alternate land use
Control of range pests and undesirable vegetation
Reclamation of soil and vegetation on disturbed areas.
35 Drainage Pattern and Texture
Six common drainage patterns are illustrated in figure 4.36 page 287
Dendritic formed by main stream with tributaries branching and rebranching freely.
Rectangular dendritic pattern modified by structural bedrock such that tributaries meet at right angles. Typical of massive sandstone formations with well-developed joint system.
Trellis drainage pattern consists of streams having one dominant direction with subsidiaries at right angles. Occurs in areas of folded sedimentary rocks.
Radial drainage pattern is formed by streams that radiate outward from a central area. Typical of volcanoes and domes.
Centripetal reverse of radial drainage pattern in that drainage is directed a central point. Occurs in areas of limestone sinkholes glacial kettle holes volcanic craters and other depressions.
Deranged disordered pattern of of aimlessly directed short streams ponds and wetland areas of ablation glacial till areas.
36 Erosion
Gullies are small drainage features that can be as small as a meter wide and a hundred meters long.
Result from erosion of unconsolidated material from runoff
Develop where rainfall cannot adequately percolate into ground but collects and flows across the surface in small rivulets
Enlarge and take on shape characteristic of the material in which they are formed
Short gullies with V-shaped cross sections tend to develop in sand and gravel (figs 4.38 and 4.39 pages 288 and 289).
Gullies with U-shaped cross sections tend to develop in silty soils (figs 4.38 and 4.39).
Long gullies with gently rounded cross sections tend to develop in silty clay and clay soils (figs 4.38 and 4.39).
37 Water Resource Applications
Water is one of our most critical resources uses are
Irrigation
Power generation
Drinking
Manufacturing
Recreation
Most sunlight absorbed within two meters of waters surface.
Absorption highly dependent on wavelength.
Near IR absorbed in few tenths of a meter of water resulting in very dark tones.
Absorption in visible portion dependent on characteristics of water body.
Best wavelengths for clear calm water penetration between 0.48 and 0.60 m (up to 20 m penetration).
Sand bottoms appear blue-green using normal color film
Color IR film clearer because blue filtered out and essentially no near IR (two-layer film).
38 USGS Water Use Program
Analyze source use and disposition of water resources
Reply to water-use information requests
Document trends in water-use
Cooperate with agencies on special projects
Develop water-use data bases
Publish water-use reports
39 Water Pollution Detection
All natural water has some impurities.
Considered polluted when presence of impurities sufficient to limit its domestic and/or industrial use.
Not all pollutants the result of human activity.
Minerals leached from soil
Decaying vegetation
Appropriate to consider two types of pollution sources.
Point Highly localized such as industrial out-falls
Non-point Fertilizer and sediment run-off
40 Water Pollution Detection Continued
Each of the following--when present in excessive amounts--can result in water pollution
Organic wastes from domestic and industrial sources
Infectious agents from domestic and industrial wastes
Plant nutrients that cause nuisance growths
Synthetic-organic chemicals such as detergents
Inorganic chemical and mineral sources from mining / manufacturing
Radioactive pollution and temperature increases.
41 Water Quality
USGS operates two national stream water quality networks.
Hydraulic Benchmark Network (HBN).
National Stream Quality Accounting Network (NASQAN).
Streams in watershed monitored to provide descriptions of stream water quality conditions.
Understand effects of natural environment and human activities on water quality.
(USGS) 63 physical chemical and biological properties monitored during 60000 stream visits 42 USGS Hydrologlic Units Map
U.S. divided into successively
smaller hydrologic units.
21 major geographic areas
Drainage area of major river
Combined drainage areas of series of rivers
222 subregions
Area drained by river system
Reach of a river and tributaries.
Closed basins
Group of streams forming coastal drainage areas.
352 hydrologic accounting units
Cataloging unit
(USGS) 43 Environmental Assessment
Many human activities produce potentially adverse environmental effects such as
Highways railroads pipelines
Airports
Industrial sites
Power plants and transmission lines
National Environmental Policy Act (NEPA) established as national policy the creation and maintenance of conditions that encourage harmony between people and their environment.
Environmental impact statements prepared for federal action having significant impact on environment.
Remote sensing and image interpretation can be used to assist in all of the related areas
Emergency response planning
Landfill monitoring
Permitting and enforcement
Natural Disaster mitigation.
44 USGS Tracking Environmental Change
Lake Chad on edge of Sahara
Desert.
Borders four countries in West Africa.
Was once the sixth-largest lake in the world but drought has shrunk it to one-tenth its former size.
Flat and shallow so small changes in depth mean huge change in area
Was once highly productive and supported diversity of wildlife.
Scientific Assessment and Strategy Team (SAST) established to provide scientific advice and assistance regarding flood recovery in upper Mississippi River Basin.
Natural flood plains
Levies dams and dikes
July 1993 (USGS) 47 Image Interpretation Process Wrapup
Through analysis an image interpreter can identify different terrain conditions and determine the boundaries between them.
Topography
Drainage pattern and texture
Erosion
Image Tone
Vegetation
Land use
Above elements considered individually and in combinations to estimate terrain conditions.
Image interpretation is readily used in examining bedrock types
Principles of Photogrammetry R. Lathrop with Material from Avery and Berlin 5th Editionhttp//deathstar.rutgers.edu/courses/airph oto/airphoto7/sld001.htm
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