1. A SIMULATION STUDY OF TOPOGRAPHIC EFFECTS ON POLSAR CLASSIFICATION OF FORESTS AND CROPS M. L. Williams 1 and T. L. Ainsworth 2 1 Cooperative Research Centre for Spatial Information 2 Remote Sensing Division, Naval Research Laboratory

11. With azimuth slope set to zero, the orientation angle does not depend on range slope. Range Slopes in Grassy Regions Orientation Angle & Correlation |  4 | Low orientation angle correlations without a strong dependence on range slope. Slightly lower for positive slopes.

12. Grass Region Forest Small range tilt reduces double bounce power in forest, but not in the grassy regions. Range Slopes in Forest Area Double Bounce Power & Ground-Forest Component Ground-Forest Component The ground-forest multiple scattering accounts for the rapid drop of the double bounce backscatter. All tree trunks are perfectly vertical – not a good approximation.

13. The orientation angle basically matches changes in azimuth slopes. Azimuth Slopes in Grassy Regions Orientation Angle & Correlation |  4 | Low correlation values imply poor estimates of orientation angles.

14. Grass Region Forest Small azimuth tilts allow ground-trunk scattering, only larger slopes reduce double bounce power in forest. Azimuth Slopes in Forest Area Double Bounce Power Ground-Forest Component The ground-forest multiple scattering component accounts for double bounce changes with azimuth slope. Tree trunk forward scattering is not limited to specular directions.

15. The orientation angle basically matches changes in azimuth slopes. Azimuth Slopes in Forest Area Orientation Angle & Correlation |  4 | Higher correlation values in forest area imply good estimates of the orientation angles.

16. Full SAR Simulation Azimuth Slopes in Forest Area Orientation Angle Orientation angle estimates from full SAR simulation closely matches the orientation angles of the strong ground-forest scattering component. The ground-forest induced orientation angle shows low variance (high correlations) independent of azimuth slope. The orientation angle variance from the full simulation increases with increases in the azimuth slope. Ground-Forest Component

17. Full SAR Simulation Azimuth Slopes in Forest Area Scatter Shape Variation The Shape Variation reflects inherent changes to the polarimetric scattering. Even after orientation angle compensation, once the azimuth slopes exceed ~6 °, the ground-forest scattering component changes character. The double bounce scattering, probably generated from ground-trunk interactions, is greatly reduced. This change in Shape Variation is consistent with the  -angle changes due to azimuth slopes shown earlier. Ground-Forest Component

18. Grassy Region Major Forest Scattering Components Forest scattering, at least for our simulated Scots Pine forest, is almost completely specified by the Direct Forest ( blue ) and the Ground-Forest ( green ) scattering components. The cyan curve, the combination of Direct Forest and Ground-Forest scattering, almost exactly matches the Full Scattering curve ( red ). Forest Returns

19. Major Forest Scattering Components The Full Orientation Angle Correlation matches the Correlation formed from the Direct Forest and Ground-Forest scattering components. Similarly, the Full Shape Variation reflects the combination of the Direct Forest and Ground-Forest scattering.

22. Background