Advanced Ortho Image Processing IGIC 2010

2 Advanced Ortho Image Processing Outline ■About Surdex ■Digital Acquisition Trends ■Image Processing ■Image Processing Approach ■Questions and Answers

3 Advanced Ortho Image Processing Surdex ■Surdex headquartered in St. Louis, MO area ■Over a half-century of photogrammetric mapping ~100 employees 7 aircraft – 4 Cessna 441 (Conquest) Turbine Aircraft 3 Intergraph Digital Mapping Cameras (DMC) 5 film cameras LiDAR ■Very progressive R&D Large amount of proprietary algorithms and software Focus on cost-efficiency and performance

4 Advanced Ortho Image Processing Surdex’s Digital Camera ■Own and operate 3 Intergraph DMCs Digital Mapping Camera Operated since summer, 2005 ■Large-format digital frame camera Simultaneous capture of panchromatic, color, near infrared 12 bits/pixel potential dynamic range 500MB per exposure ■>600,000 exposures processed

5 Advanced Ortho Image Processing Multispectral Imagery (Minnesota NAIP, 2008)

6 Advanced Ortho Image Processing Multispectral High-Resolution Imagery

7 Advanced Ortho Image Processing ~3” Resolution (Ottawa, Canada, 2007)

8 Advanced Ortho Image Processing Digital Imaging – From 4+ Miles Up 2’ DOQQ & Close-Up

9 Advanced Ortho Image Processing Digital Acquisition Trends ■Film  digital faster than most “experts” imagined 40+ large-format digital cameras in North America Doubled in last 3 years Numerous companies have completely abandoned film Film suppliers reducing emulsion offerings ■Trends Increasing demand for “4-band” (R,G,B,NIR) Increasing demand for stereo Increasingly aggressive schedules ■Many operators have developed their own software

10 Advanced Ortho Image Processing Image Processing for Results ■What does the client want? Pretty picture? Support detailed GIS analysis? Match the last project? Hardcopy or softcopy? ■Client must be involved in establishing “colorimetry” Color – easiest to establish Contrast – affects brightness and sharpness Brightness – interlocked with contrast ■Digital imagery – “what color do you want?”

11 Advanced Ortho Image Processing Resolutions & Flying Height 0.4’ (4,000’)0.5’ (5,000’)0.6’ (6,000’)0.7’ (7,000’)0.8’ (8,000’) 20% lownominal20% high40% high60% high Actual Surdex DMC Test Imagery All Exposures Taken Within ~1 Hour Timeframe All Remapped to (target) 0.5’ GSD

12 Advanced Ortho Image Processing Color Variation Courtesy ITT Space Systems

13 Advanced Ortho Image Processing Calibrated Monitors are a Must! Courtesy ITT Space Systems Actual Pictures of Same Image on Different Monitors!

14 Advanced Ortho Image Processing Linear CCD response needs correction Gamma (Logarithmic) Correction

15 Advanced Ortho Image Processing Processing of Digital Imagery ■Use reference images from acquisition Work with client to get the desired look Lock down “colorimetry” before production begins ■Why? Client has ownership in what deliverables look like Less alteration of the imagery in the last step Less re-work, better performance (schedule) Reduces QC to accuracy and artifact scrutiny

16 Advanced Ortho Image Processing Key Points ■Technicians sort raw images into “groups” Geopositioned using ABGPS/IMU Common scene characteristics 1,000’s of images loaded at once ■Enhancements are prototyped ■Batch-processing in distributed environment ■12bpp processing – option to output to 8bpp ■4-band processing to output color and CIR

17 Advanced Ortho Image Processing Processing ■Gamma correction Initial targeting of image metrics ■Digital dodging Offset atmospheric haze Offset localized brightness/contrast variations ■Solar correction (“hot spot” removal) Offset solar illumination (especially for high-altitude) Aided by sun ephemeris data and ABGPS Automated with operator override ■Full 12 bpp processing Option to output in 8 bpp at completion

18 Advanced Ortho Image Processing Image Processing Flow Example (NAIP08) 1. Grouping of images 2. Gamma correction 3. Correct to color metrics Dodging to remove local variations Solar correction to offset sun illumination

19 Advanced Ortho Image Processing Uncorrected 12-bit Raw Image Image Processing Flow

20 Advanced Ortho Image Processing Image Processing Flow Initial Gamma Correction

21 Advanced Ortho Image Processing Image Processing Flow Solar Correction

22 Advanced Ortho Image Processing Image Processing Flow Digital Dodging

23 Advanced Ortho Image Processing Pre-Production vs Final Product – “WYSIWYG”

24 Advanced Ortho Image Processing Effectiveness of the Approach ■NAIP states -- ~540,000 sq mi ~100,000 exposures ~34,000’ MSL ~38,000 1m resolution X 4-bands 5.5 months from acquisition through final delivery ■Despite incremental product processing: Achieve overall state consistency Achieve “national” consistency ■The keys: Reference imagery process Colorimetry established before production

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27 Advanced Ortho Image Processing Delivering Seamline Data ■New deliverable to all clients ■Seamline polygons with attributes Date/time of acquisition Camera & aircraft IDs Size of polygon ■Why? Provide guidance to client or 3 rd party QC – most errors are related to seamlines Provide a date for each pixel – desired by some for historical reasons

28 Advanced Ortho Image Processing Common Seamline Error – and Resolution

29 Advanced Ortho Image Processing Seamlines – Spokane, WA 2009

30 Advanced Ortho Image Processing Closing Comments ■Clients and contractors must work together to establish colorimetry prior to production No surprises upon delivery Assures schedule Reduces cost ■Take advantage of the content of digital sensors 12bpp == 8X more data than scanned film 4-band (color + CIR)