| Model ID: | M00037 | ||||||
| Model Name: | 3D Radar Backscatter Model of Forest Canopies | ||||||
| Encoders: |
|
||||||
| Key words: | Forest, 3D forest scene, Radar，Backscattering coefficients | ||||||
| Model Type: | Theoretical model | ||||||
| Latest Modified: | 2014/9/17 0:00:00 | ||||||
| Submission Date: | 1998/11/3 0:00:00 | ||||||
| Abstract: | The model was developed by Professor Guoqing Sun at University of Maryland and Professor Kenneth Jon Ranson at NASA Goddard Space flight Center and was further improved by Wenjian Ni at institute of remote sensing applications CAS. Matrix- doubling method was used in the improved model to consider the multiple-scattering within forest canopies. The model was developed based on 3D Forest scene described by cubic cells。Therefore，both the horizontal and vertical heterogeneities could be accounted for. The scattering components considered in this study include direct backscattering from forest canopy, direct backscattering from ground, direct backscattering from trunks, double scattering between forest canopy and ground, double scattering between trunks and ground. | ||||||
| Equation: |
| 1 |
Name: leaf shape
|
Parameter type: String
|
Physic Entity: leaf shape
|
| 2 |
Name: incidence angle of SAR in degree
|
Parameter type: double
|
Physic Entity: incidence angle of SAR in degree
|
| 3 |
Name: Band of SAR
|
Parameter type: String
|
Physic Entity: Band of SAR
|
| 4 |
Name: mean length and radius of branches
|
Parameter type: double
|
Physic Entity: mean length and radius of branches
|
| 5 |
Name: the minimum tree DBH
|
Parameter type: double
|
Physic Entity: the minimum tree DBH
|
| Title: | A three-dimensional radar backscatter model of forest canopies | |||||||||
| Authors: |
|
|||||||||
| Cited by: | Geoscience and Remote Sensing, IEEE Transactions on | |||||||||
| Abstract: | A three-dimensional forest backscatter model, which takes full account of spatial position of trees in a forest stand is described. A forest stand was divided into cells according to arbitrary spatial resolution. The cells may include “crown”, “trunk”, and “gap” components, determined by the shape, size and position of the trees. The forest floor is represented by a layer of “ground” cells. A ray tracing method was used to calculate backscattering components of 1) direct crown backscatter, 2) direct backscattering from ground, 3) direct backscattering from trunk, 4) crown-ground scattering, and 5) trunk-ground scattering. Both the attenuation and time-delay of microwave signals within cells other than “gap” were also calculated from ray tracing. The backscattering Mueller matrices of these components within the same range intervals were incoherently added to yield the total backscattering of an image pixel. By assuming a zero-mean, multiplicative Gaussian noise for image speckle, the high-resolution images were aggregated to simulate a SAR image with a given spatial resolution and number of independent samples (looks). A well-characterized 150 m×200 m forest stand in Maine, USA, was used to parameterize the model. The simulated radar backscatter coefficients were compared with actual JPL SAR data. The model gives reasonable prediction of backscattering coefficients averaged over the entire stand with agreement between model and data within 1.35 dB for all channels. The correlations between simulated images and SAR data (10 by 15 pixels) were positive and significant at the 0.001 level for all frequencies (P, L, and C bands) and polarizations (HH, HV, and VV) |
Equation