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| Titel |
Refined elevation models and reflectance for HRSC images |
| VerfasserIn |
Roderick OHara, Gerhard Neukum |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250049838
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| Zusammenfassung |
| Current elevation models produced using stereo processing of HRSC images have a
much lower effective resolution than the nadir images. Refinement of these
elevation models is possible by calculating reflectance properties across the
surface and using the resulting reflectance model with a recently developed
shape from shading algorithm. Multiple reflectance parameters are found at each
point on the surface, allowing for the use of the Minnaert model, or Lambert model
with a varying offset term to compensate for atmospheric effects. As this would make the
reflectance configuration under-constrained for arbitrary reflectance variation, a
requirement of neighbouring point consistency is used to provide sufficient constraint on the problem,
while still allowing piecewise constant reflectance variation to be represented.
The effectiveness of this approach has been quantitatively shown for synthetic
surfaces. However, application to HRSC stereo elevation models is more difficult due
to the surface orientations being very inaccurate at the full resolution. Accordingly,
the elevation model is used at a greatly reduced resolution, and a filter is used to smooth
erroneous points where the assumption of neighbouring point consistency cannot be satisfied.
The calculated reflectance map is then used to refine the original elevation model using
shape from shading (also known as photoclinometry) and the reflectance parameters are
recalculated for the refined surface. The resulting high resolution elevation
model appears to be significantly more detailed than the original, and does not exhibit
obvious errors when viewed under differing illumination directions. |
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