Onshore Distance Offshore 



CD 



s 



Figure 14. Video timestack of swash 



manual refinements. Horizontal swash positions are converted to vertical runup 

 elevation using profile measurements, camera geometry, and photogrammetric 

 transformations. Fundamental to the accuracy of this system is an accurate 

 measure of the beach profile and a precise determination of the camera position 

 and view angles. Errors in profile slope or camera geometry directly affect 

 estimates of runup variance. However, small errors in beach profile 

 measurements have little effect on the shape of the runup spectra (i.e., the 

 proportion of infragravity to incident energy is relatively unaffected). Errors in 

 runup estimates associated with camera geometry can be significant if poor 

 photogrammetry solutions are obtained. Geometry errors are minimized with 

 careful photogrammetric techniques (Appendix B), and generally are not as 

 important as profile errors. 



Chapter 4 Field Observations 



33 



