digital imaging and remote sensing laboratory r.i.tr.i.tr.i.tr.i.t r.i.tr.i.tr.i.tr.i.t sensor...

Digital Imaging and Remote Sensing LaboratoryRR..II..TT

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Sensor Modeling in DIRSIGSensor Modeling in DIRSIGJune 10, 2004June 10, 2004

Cindy ScigajCindy Scigaj

Dr. John SchottDr. John SchottScott BrownScott Brown Dr. Bob Kremens Dr.Carl SalvaggioDr. Bob Kremens Dr.Carl Salvaggio

Paul LeePaul Lee Jason FaulringJason Faulring

Niek SandersNiek Sanders


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OverviewOverview

• What is DIRSIG?What is DIRSIG?

• Project definitionProject definition

• Background informationBackground information– MTF, Spectral Response (& spectral smile), NoiseMTF, Spectral Response (& spectral smile), Noise

• Lab experimentsLab experiments

• Field experimentsField experiments

• SummarySummary


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DIRSIGDIRSIG

• Physics based model Physics based model developed at RIT to developed at RIT to simulated remotely simulated remotely sensed datasensed data

• Various platformsVarious platforms– Line scanner, framing array, Line scanner, framing array,

pushbroom scannerpushbroom scanner

DIRSIG Megascene Image


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Project DefinitionProject Definition

• Historical perspective and justificationHistorical perspective and justification– Users wishing to incorporate rigorous sensor modeling to DIRSIG Users wishing to incorporate rigorous sensor modeling to DIRSIG

simulations needed to oversample the image spatially and spectrally.simulations needed to oversample the image spatially and spectrally.» Large intermediate images were requiredLarge intermediate images were required

• Project GoalsProject Goals– Add a flexible sensor model that allows users to incorporate sensor Add a flexible sensor model that allows users to incorporate sensor

models during rendering.models during rendering.» Vary properties for each detector element (pixel)Vary properties for each detector element (pixel)

– Create and distribute pre-built sensor models for “out-of-the-box” Create and distribute pre-built sensor models for “out-of-the-box” use.use.

» Potential systems: AVIRIS, WASP, HYDICE, SEBASS, COMPASS, NVISPotential systems: AVIRIS, WASP, HYDICE, SEBASS, COMPASS, NVIS» Allow users to compare results with these standardized modelsAllow users to compare results with these standardized models

– Combine efforts to create sensor model “cook-book”Combine efforts to create sensor model “cook-book”– Benefit algorithm developers/testers and instrument designersBenefit algorithm developers/testers and instrument designers

» Long term – handle tabulated dataLong term – handle tabulated data

– Overall – provide an easy way to incorporate sensor artifactsOverall – provide an easy way to incorporate sensor artifacts


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Implementation OverviewImplementation Overview• Response functionResponse function

– A set of one or more channel or band responsesA set of one or more channel or band responses– Different types of channelsDifferent types of channels

» Pass-band channels have a tabulated spectral response.Pass-band channels have a tabulated spectral response.» Spectrometers channels have a center, width and shape.Spectrometers channels have a center, width and shape.

– Both have gain and bias terms per channelBoth have gain and bias terms per channel» ““Dead” detectors introduced with zero gain valuesDead” detectors introduced with zero gain values

• Spectral Response FunctionSpectral Response Function– Pushbroom spectrometer specific issuesPushbroom spectrometer specific issues

» ““Smile” and “frown” effects can vary channel locations for each spatial detector.Smile” and “frown” effects can vary channel locations for each spatial detector.

• Point-Spread Function (MTF)Point-Spread Function (MTF)– A combination of atmosphere (turbulence), platform (jitter), optics, detector and A combination of atmosphere (turbulence), platform (jitter), optics, detector and

electronics effects.electronics effects.– Ideally, a series of PSFs stored in a functional form to ease computation and allow for Ideally, a series of PSFs stored in a functional form to ease computation and allow for

different sub-detector sampling schemes.different sub-detector sampling schemes.

• NoiseNoise– A combination of photon arrival, detector read-out and electronics.A combination of photon arrival, detector read-out and electronics.– Store the noise covariance and use a Principle Component (PC) synthesis method to Store the noise covariance and use a Principle Component (PC) synthesis method to

compute a unique noise spectrum for each scan/read-out of the detector elements.compute a unique noise spectrum for each scan/read-out of the detector elements.


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Pushbroom axis

Pushbroom axis

Spe

ctra

l axi

s

Spe

ctra

l axi

s

Area arrays

Diffraction grating

CollimatorSlit

Optics

Ground Track

Pushbroom ScannersPushbroom Scanners

• AIS (grating)AIS (grating)

• HYDICE (prism)HYDICE (prism)

• SEBASS (prism)SEBASS (prism)

• Hyperion (EO-1)Hyperion (EO-1)


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Response Function:Response Function:Spectral Smile and FrownSpectral Smile and Frown

• In pushbroom spectrometers, In pushbroom spectrometers, the spectral channel locations the spectral channel locations of pixels on the edge of the of pixels on the edge of the focal plane are different than focal plane are different than the ones in the center of the the ones in the center of the focal planefocal plane

– This effect can be modeled with This effect can be modeled with these enhancements.these enhancements.

Center PixelCenter Pixel Edge PixelEdge Pixel

Spatial

Spe

ctra

l


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Point-Spread FunctionPoint-Spread Function

• A spectrally dependent function that introduces the blur from a A spectrally dependent function that introduces the blur from a variety of sources in the image formation process.variety of sources in the image formation process.

– Atmospheric turbulence, platform jitter, optics, detector and electronics Atmospheric turbulence, platform jitter, optics, detector and electronics effects.effects.

– Ideally, each of these would be in a flexible, functional form.Ideally, each of these would be in a flexible, functional form.» Radially symmetric (Gaussian, Lorentzian, etc.)Radially symmetric (Gaussian, Lorentzian, etc.)

» X/Y separable (Gaussian, Sinc, SincX/Y separable (Gaussian, Sinc, Sinc22, etc.), etc.)

– A functional form could allow the user to change the sub-detector sampling A functional form could allow the user to change the sub-detector sampling (finer grid, N random locations, etc.)(finer grid, N random locations, etc.)

PixelDetector

PSF = PSFPSF = PSFaa(r,l) + PSF(r,l) + PSFpp(r) + PSF(r) + PSFoo(r) + PSF(r) + PSFdd(x,y)(x,y)

Cn2 jitter optics detector


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Noise:Noise:Spectral StructureSpectral Structure

• We want to introduce We want to introduce noise for each detector noise for each detector element and each scanelement and each scan

– Each detector can have Each detector can have unique noise statisticsunique noise statistics

» Non-repeating noise that can Non-repeating noise that can be described by higher order be described by higher order statistics (spectral statistics (spectral covariance/correlation)covariance/correlation)

• Due to focal plane Due to focal plane design (shared design (shared electronics) the sensor electronics) the sensor noise is correlated.noise is correlated.

– This effect can be modeled This effect can be modeled with these enhancements.with these enhancements.

AVIRIS Noise Correlation

11 22 33 44

11

22

33

44


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Modeling ConceptModeling Concept

Focal PlaneFocal Plane

Many spectral Many spectral samplessamples

• To accurately model the To accurately model the radiance at this pixel radiance at this pixel detector:detector:

– Spectrally oversampleSpectrally oversample

» Convolve to channel Convolve to channel resolution using response.resolution using response.

– Spatially oversample inside Spatially oversample inside and and outsideoutside the physical the physical detector elementdetector element

» Convolve to detector Convolve to detector resolution using PSF.resolution using PSF.

– Add spectrally correlated noiseAdd spectrally correlated noise

» Pull from statistical noise Pull from statistical noise model.model.

Many spatial Many spatial samplessamples

PSFPSFContributionContribution

RegionRegion

ProjectedProjectedDetectorDetectorExtentExtent


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Data FlowData Flow

ApplyResponse

ApplyPSF

NN Spatial Samples Spatial Samples““Many” Spectral SamplesMany” Spectral Samples

Without NoiseWithout Noise

NN Spatial Samples Spatial SamplesMM Spectral Samples Spectral Samples


1 Spatial Sample1 Spatial SampleMM Spectral Samples Spectral Samples


1 Spatial Sample1 Spatial SampleMM Spectral Samples Spectral Samples

With NoiseWith Noise

ApplyNoise

Channel ResponsesChannel Responses PSFPSF(by channel)(by channel)

NoiseNoise(by channel)(by channel)


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Wildfire Airborne Sensor ProgramWildfire Airborne Sensor Program(WASP)(WASP)

• System in development System in development at RITat RIT

• Four separate camera Four separate camera systemssystems

– Terra Pix : 0.4-0.9 micronsTerra Pix : 0.4-0.9 microns– SWIR: 0.9-1.8 micronsSWIR: 0.9-1.8 microns– MWIR: 3.0-5.0 micronsMWIR: 3.0-5.0 microns– LWIR: 8.0-9.2 micronsLWIR: 8.0-9.2 microns

• CharacterizationCharacterization– equipment specificationsequipment specifications– actual lab scenes and actual lab scenes and

measurementsmeasurements– Bayer pattern artifactsBayer pattern artifacts

WASP


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WASP Modeling CriterionWASP Modeling CriterionDIRSIG needsDIRSIG needs Terra PixTerra Pix NIRNIR MWIRMWIR LWIRLWIR

Focal lengthFocal length 0.054966 m0.054966 m 0.025307 m0.025307 m 0.025014 m0.025014 m 0.025027 m0.025027 m

# x pixels# x pixels

(Cross-track)(Cross-track)

40964096 640640 640640 640640

# y pixels# y pixels

(Along-track)(Along-track)

40964096 512512 512512 512512

X lengthX length 0.000009 m0.000009 m 0.000025 m0.000025 m 0.000025 m0.000025 m 0.000025 m0.000025 m

Y lengthY length 0.000009 m0.000009 m 0.000025 m0.000025 m 0.000025 m0.000025 m 0.000025 m0.000025 m

Spectral Spectral responseresponse

SpecsSpecs SpecsSpecs SpecsSpecs SpecsSpecs

Gain & biasGain & bias Color strips Color strips targettarget

Color strips Color strips targettarget

CI blackbodyCI blackbody CI blackbodyCI blackbody

PSFPSF Plywood targetPlywood target Plywood targetPlywood target CI blackbodyCI blackbody

W/ foil edgeW/ foil edge

CI blackbodyCI blackbody

W/ foil edgeW/ foil edge

NoiseNoise Color strips Color strips targettarget

Color strips Color strips targettarget

CI blackbodyCI blackbody CI blackbodyCI blackbody


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Lab ExperimentsLab Experiments


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Field Experiments – 06/07/04Field Experiments – 06/07/04

• Data collected on sceneData collected on scene– GPS locationGPS location

– ASD radianceASD radiance

– ASD reflectanceASD reflectance

– D&P radianceD&P radiance

– TemperatureTemperature» ThermocouplesThermocouples

» ExergenExergen

» Thermistors @ pierThermistors @ pier


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SummarySummary

• Sensor modeling statusSensor modeling status– A survey of different sensors has been performed to gather information on A survey of different sensors has been performed to gather information on

popular imaging platforms.popular imaging platforms.» This information will be used to construct distributed sensor models.This information will be used to construct distributed sensor models.» Recently became in contact with COMPASS instrument groupRecently became in contact with COMPASS instrument group

• Precal data and calibration documentationPrecal data and calibration documentation

– Correlated noise has been demonstratedCorrelated noise has been demonstrated– Simple smile case has been demonstratedSimple smile case has been demonstrated– Goal: supply significantly better default sensor modelsGoal: supply significantly better default sensor models– These new features, user interfaces and pre-built sensor models will be in These new features, user interfaces and pre-built sensor models will be in

DIRSIG 4DIRSIG 4

• Experiments statusExperiments status– WASP Lab data acquisition completeWASP Lab data acquisition complete– Image analysis programs being developedImage analysis programs being developed

» using ISO standard proceduresusing ISO standard procedures

– WASP imagery with supporting ground truth measurements have been acquired WASP imagery with supporting ground truth measurements have been acquired and need to be sorted, organized, and processedand need to be sorted, organized, and processed

– Waiting for SEBASS and COMPASS data distribution ~ 30 days?Waiting for SEBASS and COMPASS data distribution ~ 30 days?» Pre-calibrated data as wellPre-calibrated data as well


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Contact infoContact info

WASP – Terra Pix @ 3,000 ftWASP – Terra Pix @ 3,000 ft

Cindy ScigajCindy Scigaj

[email protected]@cis.rit.edu

digital imaging and remote sensing laboratory r.i.tr.i.tr.i.tr.i.t r.i.tr.i.tr.i.tr.i.t sensor...

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remote sensing laboratory

t sensor modeling

t overview

t dirsig physics

digital imaging

tabulated spectral response

sensor artifacts

flexible sensor model