VIIth International Scientific and Technical Conference From Imagery to Map: Digital Photogrammetric TechnologiesADS40 imagery processing using PHOTOMOD:technology and experiencePetr S. Titarov, Software DeveloperSeptember 17-20, 2007, Nessebar, Bulgaria

Report outline ADS 40 image acquisition

Software involved and data flows

Solving space intersection and resection problems

Processing ADS40 using PHOTOMOD

Pilot project: creating 1 : 2 000 orthoimagery

ADS 40 image acquisition

ADS 40 Level 0 imageryXYZfwkExterior orientationLevel 0 imageADS40 Level 0 images are distorted due to pushbroom imaging mode and exterior orientation instability.

ADS 40 Level 1 imagery creatingThe Level 1 image is generated by projecting Level 0 image onto the constant height plane in the Local Space Rectangular (LSR) reference frame using in-flight (not adjusted) exterior orientation.

Level 0 vs. Level 1Level 0 imageLevel 1 imageAs compared with Level 0 images, the Level 1 images are non-distorted,comfortably viewable, suitable for automatic tie points measurement.

Specific aerial pushbroom imagery artifactsOn the edge of the imageInside the imageThe gaps on the ADS40 Level 1 images are caused by abrupt exterior orientation change.Level 1 images edgesAN-30L-410

Data flows between software involvedGProLevel 0 imagery creation,automatic tie points measurementLevel 1 imagery creationORIMABlock adjustmentPHOTOMODDTM/DEM extraction, 2D/3D vectorization, orthoimagery creationAdjusted exterior orientation (*.odf.adj)In - flight exterior orientation (*.odf)Sensor calibration (*.cam)Ground control and tie pointsLevel 1 imagery + metadata (*.sup) + sensor geometric calibration (*.cam) +in-flight exterior orientation (*.odf)

GPS/IMU software, GPro, ORIMAGPS/IMU softwareGProORIMAPost-processing of the in-flightGPS/IMU measurements: POSProc/ POSGPS GrafNavImage download from on-board storage, Level 0/1 imagery generationADS 40 block adjustment

PHOTOMOD SoftwarePHOTOMOD DTMDTM derivationPHOTOMOD StereoDrawPHOTOMOD MosaicPHOTOMOD Vector3D VectorizationOrthomosaic generatingDigital map creating

Space intersection and space resection problemsSpace intersectionSpace resectionSpace intersection is solved to derive DTM.Space resection is solved to create orthoimagery.

Solving space resection problem by Level 1 imageLevel 1 space resection solving schemeLevel 0 space resectionSolving Level 0 space resection problem is time-consuming operation due to pushbroom image acquisition mode and the instability of the airborne sensor exterior orientation.The procedure consists of three stages:Iterative contracting the search area (estimating line and detector number ranges);Sequential line number search throughout the range;Calculating detector number using line number found;

Solving space intersection problem by Level 1 stereopairLevel 1 space intersection solving scheme

Selecting images for processing in PHOTOMODStereo processingOrthoimagery creating14 backward + 28 forward14 backward + nadirnadir + 28 forwardB : H = 0.25B : H = 0.78B : H = 0.53Best correlation, butworst stereo precisionBest stereo precision, but worst correlationOrthoimagery should be created using nadir images to minimize the influence of DTM errors on the orthoimage accuracy.

PHOTOMOD project structure for ADS 40 processingSince the block adjustment of ADS 40 data is performed by ORIMA, there is no reason to insert the entire block into single PHOTOMOD project.Project structure in the case of stereopair composed of nadir and off-nadir imagesProject structure in the case of stereopair composed of backward and forward images: the nadir image is added into separate strip.The orthomosaic is created using capability of PHOTOMOD Mosaic module to involve images from several PHOTOMOD projects.

Adding ADS 40 images into the PHOTOMOD projectRadiometric enhancementAutomated folder analysis and data search

Focus on reference systemsThe exterior orientation is given with respect to LSR (Local Space Rectangular) reference system.

So the connection between PHOTOMOD project reference system and LSR should be provided.

There are two ways to establish the connection:To measure at least three points with known ground coordinates on the stereopair (shift rotation scale seven parameters set will be calculated);To specify completely the PHOTOMOD project reference system - datum, map projection etc.Local Space RectangularPHOTOMOD project reference system

Pilot project: 1 : 2000 orthoimagery production scale: 1 : 2 000 sheets number: 351 orthoimagery area: 91,25 km214 backward + nadir stereopairs were used to derive DEM for orthoimagery creatingSource data images GSD: 20 cm strips number: 24 data (L0&L1) volume: 0.5 Tb Output orthoimagery

Pilot project: workflowGPS/IMU post-processingGProORIMAPHOTOMOD DTMPHOTOMOD Montage DesktopPHOTOMOD ATPHOTOMOD MosaicIn-flight exterior orientation data preparationLevel 1 imagery generatingBlock adjustmentPHOTOMOD projects creatingDTM extraction from stereopairsDeriving orthomosaic using images and DEMs from several PHOTOMOD projectsSTEP

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STEP

Pilot project: check points points number : 15 strips number: 24 images GSD: 20 cm X,Y mean errors: 20 cm Z mean error: 30 cm

Pilot project: orthoimagery samplesPanchromaticColor

Thank you for your attention!THE END