International Society for Photogrammetry and Remote Sensing

Transcription

1 International Society or Photogrammetry and Remote Sensing Commission I: Sensors, Platorms, and Imagery Commission II: Systems or Data Processing, Analysis, and Representation Commission III: Theory and Algorithms Commission IV: Spatial Inormation Systems and Digital Mapping Commission V: Close-Range Vision Technology Commission VI: Education and Communication Commission VII: Resource and Environmental Monitoring

2 Commission III Symposium 2002 Graz, Austria Congress 2004 Istanbul, Turkey

3 Relie Displacement Note: nominal scale is the same everywhere in the image

4 Frame Geometry

5 Frame Geometry with ens or arge Aperture

6 Relie Displacement ayout o vertically extended objects within an image Relie displacement as ound in rame imagery, entire image captured at same instant, relie displacement is always radial with respect to the nadir point Relie displacement as ound in pushbroom imagery, the image is built up over time by the platorm motion, relie displacement only exists within a line. It is still radial with respect to the nadir point, but there is a dierent nadir point or every line. Thereore the only component o relie displacement is cross-track, there is no along-track component. (platorm motion is up/down)

7 Relie Displacement or Nadir Imagery Ideal geometry: nadir imagery, lat terrain r Image-ground scale relationships: r R r R scale r et-right proportionalities: R R r r h h Rearrange or classic relie displacement ormula: R R h r r

8 Parallax: apparent change in position due to change in view location (sometimes called disparity) Base B x r x l x r parallax B p B p p x l x r Object distance ~ 1/p > big distance : small parallax > small distance : big parallax dp d B 2 B ( scale) B > Rate o change o parallax with respect to distance ~ scale and B/

9 R R Near point (top o tank) makes a larger excursion between the let and right exposure, compared to the base o the tank (larger parallax or larger disparity). This disparity can be processed by our eyes to sense depth. A stereo cursor can be placed on an object to measure 3D coordinates delineate 3D eatures. I image B/ is greater than our eye s b/h, then we sense vertical exaggeration. This changes the appearance, but does not hurt measurement accuracy (in act it helps).

10 Anaglyph Stereo o Mars scene shows greater disparity or parallax in oreground and less in the background or ar distance

11 Wide angle and given overlap yields large B/ ratio Narrow angle and same overlap yields small B/ ratio Can compensate or narrow angle camera by introducing strong convergence angle thus restoring avorable B/ ratio

12 igh rame rate motion imagery short baseline or small B/ (between adjacent images) Conventional aerial imagery long baseline or large B/ Correspondence is easy, since small displacements and parallaxes between adjacent images, or point tracking or optical low, but determination o heights is weak (unless you extend over many rames) Correspondence can be a challenge i large parallaxes, but determination o heights is strong

13 (X,Z ) SPOT O-Nadir Relie Displacement 822 km Focal length pix dx x m11 m12 X X k m21 m 22 Z Z x m11( X X ) + m12 ( Z Z m ( X X ) + m ( Z Z x 21 m m ( X ( X X X 22 ) + m ) + m ( Z Z ( Z Z ) ) ) ) θ 1 θ 2 M m m m m cosθ 1 sinθ 1 sinθ 1 cosθ 1 θ 3 For h300m, theta-22 deg, we have the ollowing values or theta-1 and dx: h θ 1 dx 10 deg 20 deg 27 deg 6.2 pix 10.6 pix 13.0 pix X Relie displacment or onadir SPOT is signiicant