Physically-based spectral rendering is becoming increasingly popular in both commercial and academic areas due to its ability to accurately simulate natural phenomena. However, the production of materials defined by their spectral properties is a tedious and expensive process, which makes the utilization of RGB-based assets in spectral renderers a desired feature. To convert RGB values to their spectral representations, a process called spectral uplifting is employed. As the RGB color space is a finite subset of the visible gamut, there exist multiple conversion techniques producing distinct results, which may cause color inconsistencies under various lighting conditions. This thesis proposes a method for constraining the spectral uplifting process. To be specific, pre-defined mappings of RGB values to their spectral representations are preserved and the rest of the RGB gamut is plausibly uplifted. In order to assess its correctness, this technique is then implemented and evaluated in a spectral renderer. The renders uplifted via our method show minimal discrepancies when compared to the original textures.

The majority of high-latitude Arctic land surface is underlain by permafrost. The high degree of permafrost sensitivity from climatic as well as anthropogenic factors leads to surface deformation and changing active layer. This is typically due to thawing in warmer seasons and refreezing in colder seasons. Such changes can have significant impacts on the infrastructure and hydroecological environment. Hence, the objectives of this study aimed at identifying spatial pattern and magnitude of surface deformation (uplifting and subsidence) from 2015 to 2018 using Sentinel-1A images in an army installation – Donnelly Training Area (DTA), Alaska. To achieve the objectives, Interferometric Synthetic Aperture Radar (InSAR) method was applied to 11 descending Level-1 Single Look Complex (SLC) images in thawing seasons, spanning from 8th May 2015 to 25th September 2018 with perpendicular baseline up to ±90 m. A Digital Elevation Model (DEM) of 30 m spatial resolution was employed to remove the phase contributed by altitude, to increase the accuracy of differential interferogram and for geocoding. Multilooking, Goldstein phase filtering and phase unwrapping using Minimum Cost Flow (MCF) were conducted on the resulting phase. The unwrapped phase was converted into displacement and it was then terrain-corrected. The collocation of terrain-corrected coherence and displacement was applied followed by the extraction of displacements in the areas where coherence exceeded 0.4 and the displacement was interpolated. Wilcoxon’s signed ranked test was conducted to test if the median displacements were significantly different from zero. The results showed seasonal deformation ranging from -0.43 meter to +0.34 meters. Subsidence was commonly observed between June and July when temperature was high and, uplifting was noticed as a prominent phenomenon after July and before June due to the expansive nature of silty soil and clays. However, the secular changes from May 2015 to May 2018 showed subsidence as a major phenomenon. This could be attributed to the thawing of ice-rich permafrost underneath probably due to global warming and military training activities. Deformations in all pairs were found to be significantly different from zero. These results corroborate with deformation studies conducted in other parts of Alaska and these findings are useful to researchers, decision-makers, and planners of land management.

In structural mechanics there are several occasions where a linearized formulation of the original nonlinear problem reduces considerably the computational effort for the response analysis. In a broader sense, a linearized formulation can be viewed as a first-order expansion of the dynamic equilibrium of the system about a `static¿ configuration; yet caution should be exercised when identifying the `correct¿ static configuration. This paper uses as a case study the rocking response of a rigid block stepping on viscoelastic supports, whose non-linear dynamics is the subject of the companion paper, and elaborates on the challenge of identifying the most appropriate static configuration around which a first-order expansion will produce the most dependable results in each regime of motion. For the regime when the heel of the block separates, a revised set of linearized equations is presented, which is an improvement to the unconservative equations published previously in the literature. The associated eigenvalues demonstrate that the characteristics of the foundation do not affect the rocking motion of the block once the heel separates.