Transcript Sub Pixel Classification

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SUB PIXELCLASSIFICATION
Contact: [email protected]
Mirza Muhammad Waqar
Lecture Overview
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Image classification
Sub Pixel Classification
Sub Pixel Classification – Principal
Components of IMAGINE Subpixel Classifier
Preprocessing
 Environmental Correction
 Signature Refinement
 Material of Interest (MOI) Classification
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Unique Features
Benifits
Image Classification
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The key objective of classification is to
 Allocate
each pixel of a remote sensing image into
only one class (Hard or Per-Pixel Classification) or
 To associate the pixel with many class (i.e. soft, subpixel classification)
Sub Pixel Classification
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Subpixel Classifier is an advanced image
exploitation tool designed to detect materials
that are smaller than an image pixel, using
multispectral imagery.
It addresses the “mixed pixel problem” by
successfully identifying a specific material when
materials other than the one you are looking for
are combined in a pixel.
Sub Pixel Classification
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It is a powerful low cost alternative to
 Ground surveys
 Field
sampling
 High-resolution
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It discriminates between spectrally similar
materials, such as
 Individual
plant species
 Specific water types
 Distinctive man-made materials.
Sub Pixel Classification
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It allows you to develop spectral signatures that
are scene-to-scene transferable.
Subpixel Classification – Principal
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IMAGINE Subpixel Classifier
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IMAGINE Subpixel Classifier is part of ERDAS
IMAGINE Professional software.
 It
can be used with imagery from any 8-bit or 16-bit
airborne or satellite multispectral imaging platform.
 Currently,
the most common sensor used is the Landsat
Thematic Mapper (TM).
 SPOT Multispectral (XS), DigitalGlobe QuickBird, and
Space Imaging’s IKONOS imagery are also widely used
data sources.
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The software can also
hyperspectral imagery.
be
used
with
Components of IMAGINE Subpixel Classifier
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IMAGINE Subpixel Classifier
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Preprocessing
Environmental Correction
Signature Derivation
Signature Refinement
Material of Interest (MOI)
Classification
Two Data Quality
Assurance Utilities
1. Preprocessing
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Preprocessing is an automated process that must be
performed prior to developing a signature or
performing MOI Classification.
There are no interactive results to view, but a
preprocessing output file is created. This file is used
by other IMAGINE Subpixel Classifier processes.
Preprocessing need only be performed once per
image. You can use the same output each time you
perform classification or signature derivation.
2. Environmental Correction
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Environmental Correction compensates for
unwanted spectral variations in scene pixels.
These variations are caused by differences in
atmospheric
and
other
environmental
conditions.
One of the benefits of this correction is that
signatures derived from corrected images are
scene-independent.
3. Signature Derivation
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Manual Signature Derivation is used to generate a
single signature from a fixed set of input
parameters.
Use Manual Signature Derivation when you want to
generate a signature from a whole-pixel training set.
To derive an IMAGINE Subpixel Classifier signature,
you must identify pixels which likely contain the
material of interest.
4. Signature Refinement
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Signature refinement tool is used to refine
extracted signatures.
5.
Material of Interest (MOI) Classification
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Classification is the process of finding those
pixels
 within
the scene which have spectral properties
that are similar to a given signature material of
interest.
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IMAGINE Subpixel Classifier can identify
materials of interest even when they are
 mixed
with other materials and occupy only a
fraction of the pixel ground sample area.
Unique Features
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Multispectral detection of subpixel MOIs
The detection and classification of materials
that occupy as little as 20% of a pixel
Detection based on spectral properties, not
spatial properties
Scene-to-scene signature transfer
Benefits
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Classifies objects that are smaller than the
spatial resolution of the sensor
Identifies specific materials in mixed pixels
Creates purer spectral signatures
Can be used for many types of applications
Develops scene-to-scene transferable spectral
signatures, even at different times of the day
and year
Enables searches over wide geographic areas
Cont…
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IMAGINE Subpixel Classifier will enable you to
improve the accuracy of your classification
projects by making more complete detections.
It offers you higher levels of spectral
discrimination and classification accuracy by
detecting MOIs even when other materials are
present in the pixel.
Cont…
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By applying an entirely different approach to
background removal and signature development
than used by traditional whole pixel classifiers.
Questions & Discussion