quality control review of orthophotography

Quality Control Review of Quality Control Review of OrthophotographyOrthophotography

Matt McCormack, I.M.A.G.I.S.Matt McCormack, I.M.A.G.I.S.

Goals to talk about todayGoals to talk about today

• DefinitionsDefinitions• How the Orthophotography Project How the Orthophotography Project

deliverables and specifications influence deliverables and specifications influence reviewreview

• The how’s and what’s of reviewing the The how’s and what’s of reviewing the ortho and other related deliverablesortho and other related deliverables

• Examples, last thoughts, and finally…Examples, last thoughts, and finally…• Questions and (hopefully) answers Questions and (hopefully) answers

sectionsection

DefinitionsDefinitions

• Orthophotography- aerial photos that Orthophotography- aerial photos that have been “rectified” or adjusted to have been “rectified” or adjusted to form to the project terrain and geo-form to the project terrain and geo-referenced to the clients specifications. referenced to the clients specifications. Relief and camera, as well as certain Relief and camera, as well as certain “feature” distortions have been “feature” distortions have been removed, and the “frames” or “lifts” removed, and the “frames” or “lifts” have been stitched together to form a have been stitched together to form a “seamless” mosaic of the project area.“seamless” mosaic of the project area.

Single Frame OrthoSingle Frame Ortho

Multiple Rectified FramesMultiple Rectified Frames

Mosaic ProcessingMosaic Processing

Marion County Final MosaicMarion County Final Mosaic

Definitions (cont.)Definitions (cont.)

• Clarity- generally referring to the Clarity- generally referring to the amount of detail an image will amount of detail an image will render. Closely related to the flight render. Closely related to the flight height, weather conditions, lens and height, weather conditions, lens and camera quality, final pixel resolution, camera quality, final pixel resolution, and ground conditions when the and ground conditions when the mission was completed. Processing mission was completed. Processing may also affect clarity of the image.may also affect clarity of the image.

Ortho .5 foot resolutionOrtho .5 foot resolution

Ortho 2.0 foot resolutionOrtho 2.0 foot resolution


• Radiometry- bright areas and dark Radiometry- bright areas and dark areas in an image, typically adjusted areas in an image, typically adjusted for in the image processing for in the image processing technique known as “dodging”, or technique known as “dodging”, or limiting overexposure in the light limiting overexposure in the light areas of an image and doing the areas of an image and doing the opposite in dark or shadowed areas.opposite in dark or shadowed areas.

Dodging FilmDodging Film


• Color Balance- Ultimately adjusting Color Balance- Ultimately adjusting the RGB composition to achieve a the RGB composition to achieve a true color representation of each true color representation of each image and the images in the mosaic. image and the images in the mosaic. Digital cameras may over-emphasize Digital cameras may over-emphasize one or more of the red, green, or one or more of the red, green, or blue hues making this a very blue hues making this a very important step.important step.

Digital Camera ExampleDigital Camera Example

Color BalanceColor Balance

Before

After

Another ExampleAnother Example


• Ghosting- a visual anomaly in a image Ghosting- a visual anomaly in a image where there are “left over” artifacts where there are “left over” artifacts from an image used during the from an image used during the mosaicing process. Distorted, vehicles, mosaicing process. Distorted, vehicles, offset features, and blurred imagery offset features, and blurred imagery can occur as a result of the type of can occur as a result of the type of camera used, feathering routine in the camera used, feathering routine in the software, or inadequate surface data. software, or inadequate surface data.

Ghost ImageGhost Image

Orthophotography Project Orthophotography Project deliverables and specificationsdeliverables and specifications

• Revisit and know your project deliverable Revisit and know your project deliverable specifications! You can’t expect a vendor specifications! You can’t expect a vendor to “fix” what he didn’t “break”.to “fix” what he didn’t “break”.

Flight/Camera- height, lens, digital vs. film.Flight/Camera- height, lens, digital vs. film.Pixel resolution- match flight, camera, needsPixel resolution- match flight, camera, needs(consider multiple resolutions where possible).(consider multiple resolutions where possible).Surface/DTM- existing, develop new, edit previousSurface/DTM- existing, develop new, edit previousTile/Grid- naming convention, tile graphic by Tile/Grid- naming convention, tile graphic by

deliverydeliveryFormat(s)- tiffs, sids, qc area sids, twp sidsFormat(s)- tiffs, sids, qc area sids, twp sidsDelivery Schedule- increment deliveries.Delivery Schedule- increment deliveries.

Surface Error ISurface Error I

Surface Error IISurface Error II

Outdated Surface ErrorsOutdated Surface Errors

DEM makes photo “swim” from year to year – as seen in road edge.

Orthophotography Project Orthophotography Project deliverables and specifications deliverables and specifications (cont.)(cont.)• Know your specs (cont.)Know your specs (cont.)

Other products- CIR, Surface Data, SubsetsOther products- CIR, Surface Data, SubsetsMedium- External Hard Drive (recommend), Medium- External Hard Drive (recommend),

DVD’sDVD’sFlight Logs- Frame/Lift graphic with date/timeFlight Logs- Frame/Lift graphic with date/timePilot Area(s)- Highly recommend representative Pilot Area(s)- Highly recommend representative

pilot pilot areas! Flush out issues before production.areas! Flush out issues before production.Color Balance, contrast, and brightness Color Balance, contrast, and brightness

preferencespreferencesAsk to see samples of areas with similar Ask to see samples of areas with similar

specs/needs.specs/needs.Extra Flights Downtown/True OrthosExtra Flights Downtown/True Orthos

Traditional Ortho 07Traditional Ortho 07

True Ortho 05True Ortho 05

Traditional vs. True Orthos

Orthophotography Project Orthophotography Project deliverables and specifications deliverables and specifications (cont.)(cont.)• Know your specs (cont.)Know your specs (cont.)

Is VendorIs Vendor required to “fix” bridges/featuresrequired to “fix” bridges/featuresWhat are you willing to accept vs. impact to What are you willing to accept vs. impact to organization (foliage, water, shadows, organization (foliage, water, shadows,

dates)dates)

Requirements? Not in ’93!Requirements? Not in ’93!

How to Approach the How to Approach the ReviewReview

• A planned approach is usually the A planned approach is usually the best, so the following slides are some best, so the following slides are some things to anticipate when setting up things to anticipate when setting up a review process.a review process.

Review Prep and StepsReview Prep and Steps

• Plan for huge amount of data!Plan for huge amount of data!DEMS, CIR, Tiffs need LOTS of roomDEMS, CIR, Tiffs need LOTS of room

• Select Review SoftwareSelect Review SoftwareFamiliarity and ease of use!Familiarity and ease of use!

• Plan for Staff TimePlan for Staff TimeDelivery Schedules always change!Delivery Schedules always change!Train so everyone on same pageTrain so everyone on same page

• Develop and Follow ProcedureDevelop and Follow ProcedureDocument, especially for multiple StaffDocument, especially for multiple Staff

Review Prep and Steps Review Prep and Steps (cont.)(cont.)• Image Review DocumentationImage Review Documentation

DateDateInitialsInitialsComments (standardize)Comments (standardize)Observation Location (x/y, tile, point or graphic)Observation Location (x/y, tile, point or graphic)Screen Capture (ie, SnagIt)Screen Capture (ie, SnagIt)Graphic- Shape file with fields in .dbf, Spread SheetGraphic- Shape file with fields in .dbf, Spread Sheet

• Submit review “issues” and questionsSubmit review “issues” and questionsDo this in a timely manner so they can act on them,Do this in a timely manner so they can act on them,it might save them time to head-off the issues early.it might save them time to head-off the issues early.

Review Prep and Steps Review Prep and Steps (cont.)(cont.)

• Submit review “issues” and Submit review “issues” and questions (cont.)questions (cont.)The sooner they get them resolve and back the The sooner they get them resolve and back the sooner you can move on to the next step, may sooner you can move on to the next step, may affect other products like county, township, or affect other products like county, township, or municipal mosaics.municipal mosaics.

Review Prep and Steps Review Prep and Steps (cont.)(cont.)

• Review re-submitted filesReview re-submitted filesCheck identified errors for resolutionCheck identified errors for resolutionGive the entire file a once over for an new Give the entire file a once over for an new

issues issues that might have occurred.that might have occurred.

What to look for during the What to look for during the reviewreview

• Now, you have all of these files to Now, you have all of these files to review, they are all loaded and review, they are all loaded and accessible. Now you need to know accessible. Now you need to know where to look for unacceptable images where to look for unacceptable images with “issues” and how to communicate with “issues” and how to communicate that back to the vendor. All the while that back to the vendor. All the while everyone is asking the same question, everyone is asking the same question, “When can I get a copy of the aerials?”. “When can I get a copy of the aerials?”. No pressure there! No pressure there!

What to look for during the What to look for during the review (cont.)review (cont.)

• Overview or First ReviewOverview or First ReviewLoad all of the tiles with the corresponding grid Load all of the tiles with the corresponding grid

and and note any missing, corrupt, or outliers (wrong note any missing, corrupt, or outliers (wrong projection or wrong/missing geocoordinates).projection or wrong/missing geocoordinates).

• Full ViewFull ViewView each tile at full view to make sure it “ties” View each tile at full view to make sure it “ties”

to to adjacent tiles, is the right image for the world adjacent tiles, is the right image for the world file, file, and isn’t missing any data, look for obvious and isn’t missing any data, look for obvious color color balance and contrast/brightness issues.balance and contrast/brightness issues.

Review Example 1Review Example 1

Wrong World FileWrong World File


• Full ViewFull ViewView each tile at full view to make sure it View each tile at full view to make sure it

“ties” to “ties” to adjacent tiles, is the right image for the adjacent tiles, is the right image for the world file, world file, and isn’t missing any data, look for and isn’t missing any data, look for obvious color obvious color balance and contrast/brightness balance and contrast/brightness issues.issues.

Missing Data at Tile Missing Data at Tile EdgeEdge


• Detail View- view at final scale or higherDetail View- view at final scale or higherView at final mapping scale (ie, 1”=100/1:1200) View at final mapping scale (ie, 1”=100/1:1200)

or or higher magnification to see detail and look for higher magnification to see detail and look for common errors or “issues”.common errors or “issues”.

Pan in a consistent pattern starting in one corner Pan in a consistent pattern starting in one corner and across or down and “snake” through the tile. and across or down and “snake” through the tile.

Increase magnification or use “window” to look Increase magnification or use “window” to look more closely at features of interest.more closely at features of interest.Note and document, then check-off reviewed tileNote and document, then check-off reviewed tilebefore moving on to next.before moving on to next.


• Detail View- ShortcutsDetail View- ShortcutsIn rural areas, may want to only zoom in on In rural areas, may want to only zoom in on

features features and areas where errors are more and areas where errors are more common, like common, like bridges, building, roads, bridges, building, roads, steams. This will increase steams. This will increase your speed (and your speed (and lessen the boredom). Reference lessen the boredom). Reference data like a data like a state or county bridge, road, or drainage state or county bridge, road, or drainage mapping file can be a great time saver. More mapping file can be a great time saver. More built-built- up areas require more time and diligence.up areas require more time and diligence.

Source Reference Data Source Reference Data

What to look for during the What to look for during the review-Common Features and review-Common Features and Problem AreasProblem Areas• Warped bridges, overpasses, and Warped bridges, overpasses, and

above ground featuresabove ground featuresSurface data does not always support the Surface data does not always support the rectification of these features, so it is not rectification of these features, so it is not

uncommon uncommon to find these features distorted.to find these features distorted.

• Distorted roads, railroads, linear Distorted roads, railroads, linear featuresfeatures

Long straight features should be review for Long straight features should be review for distortions like offsets at seams, dips, holes distortions like offsets at seams, dips, holes

or hills or hills in the elevation can cause curved in the elevation can cause curved distortions along distortions along linear features.linear features.

Overpass DistortionOverpass Distortion

Linear Feature IssueLinear Feature Issue

Pavement warped at Pavement warped at overpassoverpass

What to look for during the What to look for during the review-Common Features and review-Common Features and Problem AreasProblem Areas• Buildings/Large StructuresBuildings/Large Structures

Buildings and large above ground features Buildings and large above ground features that have that have imagery from more than one image will imagery from more than one image will look like look like they have collapsed, a common they have collapsed, a common seaming error in a seaming error in a mosaic.mosaic.

• Excessive building “lean” or warpingExcessive building “lean” or warpingUrban or downtown areas often have Urban or downtown areas often have

additional additional images to minimize the “leaning” images to minimize the “leaning” caused by caused by displacement, and large buildings displacement, and large buildings sometimes appear sometimes appear wavy or warped during wavy or warped during rectification.rectification.

Seam and “Collapsed” Seam and “Collapsed” FeatureFeature

Visual Clue?Visual Clue?

Seam or Feather IssueSeam or Feather Issue

Seam Line ErrorSeam Line Error

Seam Line Error IISeam Line Error II

Image Smear at BridgeImage Smear at Bridge

Distorted BuildingDistorted Building

What to look for during the What to look for during the review-Common Features and review-Common Features and Problem Areas (cont.)Problem Areas (cont.)• Excessive or long shadowsExcessive or long shadows

Should be flown at a time of day that Should be flown at a time of day that minimizes this minimizes this problem, exacerbated by problem, exacerbated by contrast/brightness issues.contrast/brightness issues.

• Ground/Atmospheric ConditionsGround/Atmospheric ConditionsSnow cover, Foliage, Flooding, Clouds or Haze Snow cover, Foliage, Flooding, Clouds or Haze

are are all issues that should meet specifications.all issues that should meet specifications.

• Seams/FeatheringSeams/FeatheringCutting through building, fuzzy along Cutting through building, fuzzy along

features, features, mismatchingmismatching

Shadows, Building LeanShadows, Building Lean

What else to look for during What else to look for during the reviewthe review

• Ground AccuracyGround AccuracyMeasure Targets/ControlMeasure Targets/ControlCompare to planimetrics or previous OrthosCompare to planimetrics or previous Orthos

Beware: old source my be LESS Beware: old source my be LESS accurateaccurate

Find other Source Data for comparisonFind other Source Data for comparisonSurvey field checksSurvey field checksMeasure pre-selected “blind” control pointsMeasure pre-selected “blind” control points

Target or PanelTarget or Panel

Use other sources when available

Using Pictometry to show distortion in Ortho

Guitar PoolGuitar Pool

Last ThoughtsLast Thoughts

Consider Contracting with a Consider Contracting with a qualified Vendor if you have qualified Vendor if you have

the resources……the resources……

Questions????Questions????

Thanks for listening, and have Thanks for listening, and have a great day!a great day!

quality control review of orthophotography

Documents

specifications cont

project area

dark areas

project terrain

shadowed areas

samples of areas

light areas

image processing technique