TWC Remote Sensing Image Interpretation in

Geological works

Xiaogang (Marshall) Ma

Tetherless World Constellation

Rensselaer Polytechnic Institute

Geo I course, 2013-11-14

TWC • Acknowledgements

– The majority of this lecture is from Dr. Tsehaie Woldai’s

lecture ‘Image Interpretation - Part 1’ in a course RS &

GIS for Earth Resources Exploration at ITC, Enschede,

The Netherlands, in 2009

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TWC

1. Geological mapping, remote sensing data and

image interpretation

TWC

North Africa: Landsat MSS (b7,5,4)

Geological mapping is the starting point for all understanding of the earth's crust and hence for

all logically conceived programs of exploration for earth resources

Geological Mapping

Geologists follow paths of exploration and discovery in quest of solutions to some of society's most challenging problems.

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TWC Printed maps and digital maps

日本語 / English English / Español / Português

TWC Geological map online services

OneGeology

• 116 nations participating by

middle 2010

• 50 of them providing

geodata services online

• Most data are in English

http://www.onegeology.org/portal

TWC • Use of Earth orbiting satellites to capture information about

the surface and atmosphere below

• Satellites vary depending on how much detail can be seen,

what parts of the electromagnetic spectrum are sensed

• Signals transmitted to Earth receiving stations where they

are transformed for dissemination as digital images

Courtesy: http://www.ncgia.ucsb.edu/giscc/units/u002/u002.html

Remote Sensing (RS)

TWC Two main types of RS

• Passive RS:

– detect natural radiation (e.g., sunlight) that is emitted or reflected

by the object or surrounding areas

• Active RS:

– emits energy (e.g., laser light) in order to scan objects and areas

whereupon a sensor then detects and measures the radiation that

is reflected or backscattered from the target

Images from:

http://www.rsgisrs.com/rs_types.htm

TWC A few RS systems

• Airphotos

• Airborne Multispectral/Hyperspectral Scanners

• Airborne Thermal Scanners

• Airborne Radar

• Satellite Photography

• Satellite Digital Imagery

• Side-Scan Sonar

• Laser Altimeters

TWC

Night lights of Australia as observed by the Visible Infrared Imaging Radiometer

Suite (VIIRS) on the Suomi NPP satellite in April and October 2012

TWC

More information: http://earthobservatory.nasa.gov/IOTD/view.php?id=80030&src=fb

Fires

TWC • Composition of earth materials

Detect, identify, measure geological features

• Dynamic processes in the Earth

Monitor and measure geodynamic processes

• Environmental impact

Identify, monitor and assess Rem

ote

S

en

sin

g

RS for geology -

What do geologists want to know?

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TWC • RS A multifaceted TOOL for

geology

• Analysis of RS data for

Geological applications

– Measure physical characteristics

of geo-bodies

– Geological interpretation

Why the need for remote sensing

data?

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TWC Why the need for remote sensing

data?

1. Synoptic View

2. Construct regional

geological maps, useful

for small scale analyses

3. Planning field traverses to

sample and verify various

units for detailed mapping

4. Understand the spatial

distribution and surface

relationships between the

units

5. Cost, time

A synoptic view of regional scale is a much different perspective than point ground observations when trying to map lithological or structural elements.

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TWC

Landsat TM of the Bogda Shan Mts., Xinjiang Uugur Aut. Region, China

Broad Regional Coverage -

Synoptic View

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TWC Analyzing Complex Areas -

Uniform Accuracy and Precision

Ophiolite

Assemblage

Metavolcano-Sedimentary

Assemblage

Granitoids

Gneissic Terrain

Gneissic Terrain

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TWC

Digital Terrain Model ASTER data (b3n/3b)

Dataset in hand for Image

Interpretation

Perspective view 17

TWC Creation of DEM’s/Anaglyphs

Algeria Morocco Anaglyphs From: Drury, 2002

Dataset in hand for Image

Interpretation

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TWC Possibility of

stereo viewing

Southern Image Northern Image

Stereo Pair - New York City USA

SPOT,

Radarsat,

etc.

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TWC Geoscience knowledge management system

Needs of Geological Surveying Organizations

Priorities of Geological Surveys are changing -

away from publication of maps and related documents

towards maintaining a geoscience knowledge management system of reusable elements

from which users can obtain specific responses to meet their specific needs, with maps seen as illustrative

visualizations, not as end products

Text c. British Geological Survey 20

TWC Geological Survey organizations also cannot afford to send

their staff into the field indefinitely mainly because they

cannot afford it anymore

Hence there is a dire need for image interpretation prior to

fieldwork mapping to reduce cost, time and energy.

Geoscience knowledge management system

Needs of Geological Surveying Organizations

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Text c. British Geological Survey

TWC Image interpretation can be defined as:

• The study of the imaged objects using the

image/photo interpretation criteria;

• The extraction of those features relevant to the object

of study;

• The analysis of the selected features with the

objective to come to a deduction of their significance

for the specific field of study.

Image interpretation - Definition

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TWC

2. Principles and steps in RS image interpretation

TWC Knowledge-driven image interpretation -

Leading principles

Capitalizes on use of

available information

Employs qualitative &

quantitative interpretation

methods

Exploits image data from multiple

sensors for interpretation in a GIS

environment

Plays an important role

in fieldwork planning

Traverse 2004-

22

n

3

2

1

X.............

X

X

X

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TWC What information can be obtained from

RS images

• Topographic pattern

• Drainage pattern

• Landform units

• Lithological/rocks units

• Geological structures

• Mineral deposits location

• Susceptible area for erosion, mass-movement,

earthquake, volcanic, etc.

TWC Geological RS image interpretation

• The aim is to obtain lithological, stratigraphy and

geological structure

• The status is not as an alternative of field geology;

fieldwork always carried out to check the result of

the image interpretation; the results of the image

interpretation are supposed similar with data from

other sources.

TWC Geological map resulting from RS

image interpretation

• Lithological units: may composed of single rock or group

of rocks

• Geologic structures indicators: dip slope, bedding plane

• Continue or discontinue of the bed layers

• Indicators of fault and unconformity

• Landform units

• Drainage pattern, can be used to identify the lithology and

structure

• Control point, important location, ground control

TWC How to upgrade the geoscience

knowledge base through the use of RS?

• How do we actually extract geological information from images?

• What are the criteria?

• Which methods can be employed?

• How can it support mapping?

• What are the success factors?

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TWC Image characteristics for interpretation

purposes

• Tone

• Texture

• Pattern

• Shape/form

• Site

• Association

• Shadow

TWC How to interpret the lithology

• Lithological units are easily to identify from remote

sensing image (especially aerial photograph):

– Sandstone

– Shale stone

– Limestone

– A certain igneous and metamorphic rocks

– Unconsolidated material, such as: sand, gravel, clay

– Intercalation resistance and non resistance rocks

TWC Igneous rocks

• Based on mineral composition:

– Acidic: light photo tone

– Intermediate: light to medium photo tone

– Basic: dark to dark photo tone

• Extrusive rocks:

– Associate with volcanic landform

– Porosity and permeability: high

– External drainage

– Basic lava: shield volcano, joint are predominate

– Acidic lava: bocca, spatter cone, lava blister

– Intermediate lava: strato volcano

• 3.Intrusive rocks:

– Homogeny

– Topography hummocky (humid) and sharp (arid)

– Joint: frequent

– Drainage pattern with low density

TWC Metamorphic rock

• Massive topography, stratigraphy not clearly appear

• Permeability is low; drainage density high to medium;

drainage pattern: dendritic, trellis or parallel.

• Quartzite: resistant, massive topography, low

permeability, dendritic, trellis; gray photo tone

• Marble: in arid and semi arid resistant, in humid similar to

limestone

• Slates: low resistant, high drainage density, dendritic; dark

to medium gray

• Gneiss: resistant, massive topography, low permeability,

dendritic, trellis; gray photo tone

TWC Geological structure

• FLAT-LAYING BEDS:

– Contrasting tone of different sedimentary rocks

– Break of slope along the contour

– Dendritic drainage pattern

• DIPPING BEDS (FOLDS)

– Topographic surfaces coincide with bedding surface

– Asymmetrical slope can be used to determine the direction of the

dip

– Pattern of outcrop on valley can be used to determine the direction

of the dip

– Major stream usually flow parallel to the strike of the stratified beds.

TWC – Linear features/lineaments, thin rather than short, in regular

direction

– Intersecting joint approximately at right angles (vertically, dipping)

give a blocky pattern of the topography.

– In fine grained clastic rocks joint are generally more closely spaced

• FAULTS

– Linear features/lineament

– Triangle facet

– Alignment of vegetation, straight of river/stream segment,

alignment of lakes, ponds and springs

– Changes of tone, drainage and erosional features on opposite of

linear features

– Alignment of topography

TWC

Let’s take

the Doon Valley (Dehradun Area), India

as an example

TWC

Dehradun

LOCATION

TWC Let’s first review a slide from the lecture ‘Crustal

Deformation & Mountain Building (Orogenesis)’

TWC Plate tectonics:

Continent - Continent

extent, deformation from collision

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TWC Geology of the Doon Valley –

India collision with Asia

• During the Early Cretaceous (100 to 150 million years ago),

India broke away from Gondwana and began drifting North

– Oceanic lithosphere was consumed at a subduction zone along the

southern margin of Asia

• About 40 to 50 million years ago, India collided with Asia

– But because India was too light to subduct, it thrust under Asia

TWC

Convergent Boundary Continent - Continent

Model for India and Asia Collision

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TWC Continued Convergence

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TWC The Doon Valley Geology

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TWC Landsat

• The Landsat program is the longest running enterprise for acquisition

of satellite imagery of Earth.

– Landsat 1 (originally named Earth Resources Technology Satellite 1): launched July

23, 1972, terminated operations January 6, 1978

– Landsat 2: launched January 22, 1975, terminated January 22, 1981

– Landsat 3: launched March 5, 1978, terminated March 31, 1983

– Landsat 4: launched July 16, 1982, terminated 1993

– Landsat 5: launched March 1, 1984, still functioning, but severe problems since

November 2011. On December 26, 2012, USGS announced that Landsat 5 will be

decommissioned.

– Landsat 6: launched October 5, 1993, failed to reach orbit

– Landsat 7: launched April 15, 1999, still functioning, but with faulty scan line

corrector (May 2003)

– Landsat 8: Landsat Data Continuity Mission was launched February 11, 2013. May

30, 2013 Landsat Data Continuity Mission was turned over to USGS and renamed

Landsat 8.

TWC Landsat ETM+

Band Number Name Spectral Range

(µm)

Ground

Resolution(m)

1 Blue .45 to .515 30

2 Green .525 to .605 30

3 Red .63 to .690 30

4 Near Infrared .75 to .90 30

5 Shortwave IR-1 1.55 to 1.75 30

6 Thermal IR 10.40 to 12.5 60

7 Shortwave IR-2 2.09 to 2.35 30

Pan Panchromatic .52 to .90 15

The main instrument on board Landsat 7 is the Enhanced Thematic

Mapper Plus (ETM+). Landsat 7 and ETM+ Characteristics:

Landsat 7

before

launch

Source: http://igett.delmar.edu/Resources/Remote%20Sensing%20Technology%20Training/Landsat_bands-sm.pdf

TWC

TWC

Note this is a false color image:

an image that depicts an object in colors

that differ from those a photograph (a

"true-color" image) would show.

Band 4: Red

Band 5: Green

Band 3: Blue

Spectral bands are part of optical

spectra of polyatomic systems.

Current Landsat collection is that of

seven bands, including several in the

infra-red spectrum, ranging from a

spectral resolution of 0.07 to 2.1 μm.

the true color image of

an area Band 3: Red

Band 2: Green

Band 1: Blue

TWC Data collection

Georeferencing

Integrated Image Interpretation

Fieldwork, ground truthing

Synthesis and compilation

Image interpretation and project

schedule

47

!!!

Georeferencing is

often underestimated.

If not properly dealt

with from the start it

will be a pain in the

neck throughout the

live cycle of a project.

TWC

Detection

Categorization

Identification

Classification

Discrimination

Information

Data Remotely sensed datasets

Are targets distinguishable from

background? (“separability”)

Selective picking out things of informational value

Partitioning and coding

“Recognition”

Is a discipline-oriented kind of classification

Different Steps in Image

Interpretation

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TWC Sensor Return

Not diagnostic

Relate to geology

Discriminative

Diagnostic

Identification possible Categorization possible

Categorization not possible

Analysis not possible

Not discriminative

Not related

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TWC Unknown categories

Spontaneous

Recognition

External

Information

Known classes

Fe

ed

ba

ck Recognition process in visual

analysis

TWC

A

B

C

D

Spontaneous Recognition

• memory

• experience

• “data bank”

• etc.

TWC Unknown categories

Spontaneous

Recognition

External

Information

Known classes

Fe

ed

ba

ck

Recognition process in visual

analysis

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TWC Logical Inference

“man’s superior

intelligence”

• Knowledge of the

area

• Past experience in

similar terrain

• Image photo

interpretation

characteristics

TWC In the image interpretation process, the objects of our interest are

Measured* in terms of variations in:

TONE **

TEXTURE

PATTERN

SHAPE

ORIENTATION

SIZE

ASSOCIATION

SITE

* Measurements done at

- nominal scale (coding)

- ordinal scale (>,<)

- seldom used: interval, ratio ** Descriptive terms are often used

The more explicit rule for

photo/image interpretation:

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TWC Drainage pattern

The interpretation element:

PATTERN

5 Annular

Dot

Sinkhole

Knob & Kettle

Internal Draiange

Lacunate

Special Patterns

Deranged

Dichotomic

Anastomotic

Braided

Barbed

Thermokarst

Gilgai

Pinnate Pectinate Dendritic

1

Contorted Angulate Rectangular

2

Sub-parallel

Parallel

3

Radial 4

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TWC Patterns of folded and faulted rocks

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Asymmetrical + Thrust Fault

Cross fault through nose

TWC The rule of the ‘V’s

1. Dip direction != slope direction

– “V” of layer in stream points in dip

direction

2. Dip direction = slope direction

&& dip amount of layer > slope angle

– “V” of layer in stream points in dip

direction

3. Dip direction = slope direction

&& dip < slope

– V” of layer in stream points opposite

to dip dir

3 is the anomalous case!

TWC Different types of Faults

TWC Remember these from our recent

lectures?

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TWC Remember these from our recent

lectures?

60

TWC Remember these from our recent

lectures?

61

TWC Remember these from our recent

lectures?

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TWC Remember these from our recent

lectures?

63

TWC What is this? Hmm… circular pattern

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TWC It is a crater!

Manicouagan crater

It is thought to have been

caused by the impact of a 5 km

(3 mi) diameter asteroid about

215.5 million years ago (Triassic

Period).

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TWC Unknown categories

Spontaneous

Recognition

External

Information

Known classes

Fe

ed

ba

ck

Recognition process in visual

analysis

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TWC External Information

TWC Different types of images

Flat Irons on

Landsat TM+

TWC

Flat Irons on

Anaglyph

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TWC

Flat Irons/folding/

lineaments on Shaded

SRTM Data

STRM –

Shuttle Radar

Topography

Mission

TWC Faults on Landsat ETM+

TWC Folding on Landsat TM+

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TWC Folding on Anaglyph

TWC Fieldwork Representation of

Geological Information

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TWC Fieldwork Representation of Geological Information

TW, 2000

TW, 2000

TWC Before we end the lecture…

• Landsat is only one of the various sources for

remote sensing images

• And now days there are various RS systems and

various of RS data formats

• And various software programs available

• Yes, geological remote sensing is an active field

of research!

TWC Recognition Processes Self Test 1 -

relevant to the quiz in next week

Analyze a part of the Landsat TM Coverage of

the Doon Valley.

1. What is the first important thing you have to

do in order to interpret this image?

2. Spontaneous delineation of lithological

boundary is possible, but is it evident to do

direct identification of the rock type?

3. Why do we see variations in color?

4. Look into contact A and B. Are they also

geological boundaries?

5. Where do you think is the drainage divide?

6. Is Unit C the same outcrop as Unit D?

7. Compare the image with the “Geological Map

of the Dehradun Area” given in class. Could

you relate the lithological units defined in the

geological map with the image?

8. What can guide you to better definition of the

lithological units?

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TWC

Thank You

Image c. British Geological Survey