TerraPhoto Overview

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TerraPhoto Overview
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TerraPhoto task
TerraPhoto for MicroStation

• Produce orthorectified images
• Provide perspective views for
• laser data classification
• building vectorization
• powerline tower vectorization

TerraPhoto for MicroStation or TerraPhoto Viewer

• Display background raster images
• Render scenes with large image volume
• Produce flythru animations

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RectificationRequired input

• Ground surface points (laser)
• Image timing
• Camera trajectory
• Images

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RectificationProcessing steps

• Create mission definition
• Compute an image list
• Classify ground laser points (TerraScan)
• Verify improve camera calibration
• entering tie points
• Create tile rectangles
• Orthorectify

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RectificationComputing an image list

• Import trajectories with Manage Camera
  Trajectories
• time easting northing elevation heading roll
  pitch
• position of camera, laser scanner or GPS antenna
• Image timing files
• time image_file_name
• Use Compute list to interpolate from the above
• applies lever arm vector from camera calibration
• creates an image list
• time easting northing elevation heading roll
  pitch image_file_name

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RectificationTypical project strategy

• Find correct camera heading, roll and pitch
  correction
• enter manual tie points for 5-10 images
• output report with optimal camera attitude
• this is enough for reasonably well positioned
  orthophotos
• Continue work to get perfect orthophotos
• enter automatic/semiautomatic/manual tie points
  for all images
• solve lens distortion and principal point
• refine camera attitude
• run adjustment off raw image attitudes
• (heading, roll, pitch and optionally elevation of
  each raw image)

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RectificationTie point types

• Common ground same object in multiple images,
  you know it is on ground
• Common air same object in multiple images
• Known xy you know xy coordinates
• Known xyz you know xyz coordinates

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RectificationTie point value

• Known points have value 3
• Ground points have value 2
• Air points have value 1
• An image is fully defined with
• four ground points -- one close to each corner
• eight air points
• three known points
• Distribution of points is normally not perfect
• you need 5-8 ground points per image

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RectificationHeading, roll and pitch

• Image list has heading, roll and pitch for each
  image
• these are the values reported by INS
• Camera has heading, roll and pitch correction
  values
• this is the misalignment between INS and camera
• TerraPhoto computes the orientation of an image
  by adding camera correction values to image list
  heading, roll and pitch

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RectificationRectification process

• Single pass operation produces an ortho mosaic
• Quality settings determine process speed
• fast for initial ortho to support laser
  classification
• slow with best quality settings
• Produces true ortho
• when vectorized
• buildings used

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Perspective view principle

• View the world as seen by one camera image
• Viewer eye is at camera focal point xyz
• Compare any 3D information against the image

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Perspective viewsLaser data classification
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Perspective viewsBuilding vectorization
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Perspective viewsMonoscopic measurement

• Roof plane equation is known
• Camera orientation is known
• We can measure points on the plane using one raw
  image

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Perspective viewsTower vectorization
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Raster referencesSupported formats

• BMP
• CIT
• COT
• ECW
• GIF
• INT
• JPEG, JPEGJGW
• JPEG2000

• PIC
• PCX
• PNG
• RGB
• RLE
• TG4
• TIFF, TIFFTFW, GeoTIFF

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Raster referencesDisplay

• TerraPhoto draws references in top and rotated
  top views
• Not drawn in 3D rotations or perspective views

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RenderingModel components

• TerraPhoto can render city model scenes
• supports large ortho images as ECW, TIFF,
  JPG2000,
• supports large number of RPC trees
• Rendered scene may display
• vector elements from the design file (buildings,
  bridges)
• laser points drawn by TerraScan
• ground surface drawn by TerraModeler
• RPC trees
• Ortho images can be draped on
• ground surface TIN
• vector elements (building roofs, bridge surfaces)

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RenderingRPC trees

• 300-600 photos taken of a tree horizontally
• Software uses photo corresponding to viewer
  direction
• 25 USD per species www.archvision.com
• Place manually or let TerraScan detect
  automatically

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Flythru animations

• Viewer travels along a linear element
• Viewing direction defined by target lines
• lines starting from path and same graphical group
• Travel speed defined by text elements
• text origin at path and same graphical group

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Flythru animations

• Build model first
• Design viewer path, viewing direction and speed
• Set visibility of components
• Save animation as frames or as AVI file

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Training data set

• c\training
• campath camera trajectories in WGS84
• dgn
• training.dgn design file for SE or J
• training.v8 design file for V8
• training_geoid.tin geoid correction model
• images raw images as ECW or TIFF files
• laser laser points
• mission
• .001 image timing files
• training.cal camera calibration file
• training.ptc point classes
• ortho empty directory for ortho images
• temp empty directory for temporary files
• trajectory empty directory for trajectory data

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Training data set

• Camera has been used before
• internal geometry is known
• lens distortion is known
• Camera has been taken out and remounted
• misalignment is not known