1 / 4

The stereoscopic approach:

Fundamental assumptions : Lambertian reflection from the surface. The stereoscopic approach: . The difference between measured radiances at two view-angles can be used as a proxy for relative surface roughness. (1). (3). Fundamentals: .

caresse
Télécharger la présentation

The stereoscopic approach:

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fundamental assumptions: Lambertian reflection from the surface The stereoscopic approach: The difference between measured radiances at two view-angles can be used as a proxy for relative surface roughness

  2. (1) (3) Fundamentals: • For a given pixel, surface-reflected solar irradiance L (Wm-2sr-1) at a given view angle  can be approximated as: • The ratio between L at 1 and L at 2 is then: (2) Isol – incident solar irradiation (Wm-2) Re- surface reflectivity S- down-welling sky irradiance (Wm-2) fsh- effective shade fraction

  3. Can be removed using ‘dark object subtract’ Becomes a multiplicative scaling actor Assuming a laterally ~homogeneous atmosphere at the image scale t(a1) / t(a2) can be regarded as constant for the whole image. (5) Atmospheric effects: • Per pixel, the ratio between at-sensor surface-reflected solar irradiance values L(Wm-2sr-1) at view angles 1 and 2 can be approximated as: (4) Isol – incident solar irradiation (Wm-2) Re- surface reflectivity S- path radiance (Wm-2sr-1) S- down-welling sky irradiance (Wm-2) fsh- effective shade fraction t(a) – atmospheric transmissivity

  4. - can be regarded as a proxy for relative surface roughness between similarly sloping pixels within a single image. • incorporates roughness variations at all sub-pixel scales • is independent of surface composition • fairly insensitive to atmospheric effects 30° Atmospheric transmissivity is a function of path length atmosphere surface Atmospheric effects: Isol – incident solar irradiation (Wm-2) Re- surface reflectivity S- path radiance (Wm-2sr-1) S- down-welling sky irradiance (Wm-2) fsh- effective shade fraction t(a) – atmospheric transmissivity

More Related