Image analysis problems, posed mathematically as variational principles or as partial differential equations, are amenable to numerical solution by relaxation algorithms that are local, iterative, and often parallel. Although they are well suited structurally for implementation on massively parallel, locally-interconnected computational architectures, such distributed algorithms are seriously handicapped by an inherent inefficiency at propagating constraints between widely separated processing elements. Hence, they converge extremely slowly when confronted by the large representations necessary for low-level vision. Application of multigrid methods can overcome this drawback, as we established in previous work on 3-D surface reconstruction. In this paper, we develop efficient multiresolution iterative algorithms for computing lightness, shape-from-shading, and optical flow, and we evaluate the performance of these algorithms on Synthetic images. The multigrid methodology that we describe is broadly applicable in low-level vision. Notably, it is an appealing strategy to use in conjunction with regularization analysis for the efficient solution of a wide range of ill-posed visual reconstruction problems.

This paper describes two methods for constructing a depth map from images. Each method has two stages. First, one or more needle maps are determined using a pair of images. This process employs either the Marr-Poggio-Grimson stereo and shape-from-shading, or, instead, photometric stereo. Secondly, a depth map is constructed from the needle map or needle maps computed by the first stage. Both methods make use of an iterative relaxation method to obtain the final depth map.

We present methods for incorporating bubbles into a photorealistc fluid simulation. Previous methods of fluid simulation in computer graphics do not include bubbles. Our system automatically creates bubbles, which are simulated on top of the fluid simulation. These bubbles are approximated by spheres and are rendered with the fluid to appear as one continuous surface. This enhances the overall realism of the appearance of a splashing fluid for computer graphics. Our methods leverage the particle level set representation of the fluid surface. We create bubbles from escaped marker particles from the outside to the inside. These marker particles might represent air that has been trapped within the fluid surface. Further, we detect when air is trapped in the fluid and create bubbles within this space. This gives the impression that the air pocket has become bubbles and is an inexpensive way to simulate the air trapped in air pockets. The results of the simulation are rendered with a raytracer that includes caustics. This allows the creation of photorealistic images. These images support our position that the simple addition of bubbles included in a fluid simulation creates results that are much more true to life.

Shading devices have the potential to reduce peak cooling load and annual energy consumption because they can be used to control solar gain. Thus, the need to model shading devices in a glazing system analysis is important. This thesis deals with various measurement techniques and model development related to solar optics in windows with shading devices. It also considers longwave radiative properties of shading devices via model development and experimentation. The different shading devices examined were roller blinds, insect screens, pleated drapes and venetian blinds. The energy performance of windows with shading devices was modeled using a two step procedure. Solar radiation was considered in the first step by developing a multi-layer solar optical model for glazing/shading systems. This newly developed model is an extension of an existing model for systems of specular glazing layers and includes the effect of layers that create scattered, specifically diffuse, radiation in reflection and/or transmission. Spatially-averaged (effective) optical properties were used to characterise shading layers, including their beam-diffuse split. The multi-layer solar optical model estimates the system solar transmission and absorbed solar components. The absorbed solar components appear as energy source terms in the second step – the heat transfer analysis. The heat transfer analysis involves the formulation of energy balance equations and requires both effective longwave properties and convective heat transfer coefficients as input. The simultaneous solution of the energy balance equations yields the temperature as well as the convective and radiative fluxes. The effective solar optical properties of flat materials like drapery fabrics, roller blinds and insect screens were obtained by developing a new measurement technique. Special sample holders were designed and fabricated to facilitate measurements using an integrating sphere installed in a commercially available spectrophotometer. Semi-empirical models were then developed to quantify the variation of solar optical properties with respect to incidence angle. In turn, effective layer properties of venetian blinds and pleated drapes were modeled using a more fundamental net radiation scheme. The effective longwave properties of flat materials were obtained by taking measurements with an infrared reflectometer using two backing surfaces. The results enabled simple models to be developed relating emittance and longwave transmittance to openness, emittance and longwave transmittance of the structure. In turn, effective longwave properties of venetian blinds and pleated drapes were modeled using a net radiation scheme. Convective heat transfer correlations were readily available. Finally, the newly developed models were validated by measuring the solar gain through various shading devices attached to a double glazed window using the National Solar Test Facility (NSTF) solar simulator and solar calorimeter. Solar gain results were also obtained from simulation software that incorporated the models. There was good agreement between the measured and the simulated results thus strengthening confidence in the newly developed models.

Shading devices have the potential to reduce peak cooling load and annual energy consumption because they can be used to control solar gain. Thus, the need to model shading devices in a glazing system analysis is important. This thesis deals with various measurement techniques and model development related to solar optics in windows with shading devices. It also considers longwave radiative properties of shading devices via model development and experimentation. The different shading devices examined were roller blinds, insect screens, pleated drapes and venetian blinds. The energy performance of windows with shading devices was modeled using a two step procedure. Solar radiation was considered in the first step by developing a multi-layer solar optical model for glazing/shading systems. This newly developed model is an extension of an existing model for systems of specular glazing layers and includes the effect of layers that create scattered, specifically diffuse, radiation in reflection and/or transmission. Spatially-averaged (effective) optical properties were used to characterise shading layers, including their beam-diffuse split. The multi-layer solar optical model estimates the system solar transmission and absorbed solar components. The absorbed solar components appear as energy source terms in the second step – the heat transfer analysis. The heat transfer analysis involves the formulation of energy balance equations and requires both effective longwave properties and convective heat transfer coefficients as input. The simultaneous solution of the energy balance equations yields the temperature as well as the convective and radiative fluxes. The effective solar optical properties of flat materials like drapery fabrics, roller blinds and insect screens were obtained by developing a new measurement technique. Special sample holders were designed and fabricated to facilitate measurements using an integrating sphere installed in a commercially available spectrophotometer. Semi-empirical models were then developed to quantify the variation of solar optical properties with respect to incidence angle. In turn, effective layer properties of venetian blinds and pleated drapes were modeled using a more fundamental net radiation scheme. The effective longwave properties of flat materials were obtained by taking measurements with an infrared reflectometer using two backing surfaces. The results enabled simple models to be developed relating emittance and longwave transmittance to openness, emittance and longwave transmittance of the structure. In turn, effective longwave properties of venetian blinds and pleated drapes were modeled using a net radiation scheme. Convective heat transfer correlations were readily available. Finally, the newly developed models were validated by measuring the solar gain through various shading devices attached to a double glazed window using the National Solar Test Facility (NSTF) solar simulator and solar calorimeter. Solar gain results were also obtained from simulation software that incorporated the models. There was good agreement between the measured and the simulated results thus strengthening confidence in the newly developed models.

The thick-shelled river mussel (Unio crassus) is a red listed species classified as Endangered (EN) and is also considered within the Habitats Directive. The distribution in Sweden is fragmented and it is mostly occurring in the south eastern parts. We investigated the presence of Unio crassus in a section of the stream Storån, Östergötland County, from Falerum to the inflow into Lake Åkervristen. The environmental parameters investigated were water depth, bottom substrate, shading, water velocity and the slope over the water surface. In this thesis I have focused mainly on water depth and shading, comparing sites with and without mussels. In addition, I used a multivariate PCA analysis to evaluate all parameters together. The water depth was significantly larger in habitats with mussels than in those without. Shading varied from 5 to 80 %, but there was no significant difference between habitats with and without mussels. There was no correlation between water depth and mussel density and not between shading and mussel density either. The multivariate PCA analysis showed that the habitats with and without mussels were different from with regard to the PC1 axis, which included water depth, bottom substrate and water velocity. Alone, the water depth is not enough to predict the presence of Unio crassus in the stream, and it is likely that more parameters need to be considered.  Previous work indicate that the more parameters and habitats that are investigated, the more confident results can be stated of which habitats Unio crassus prefer.

Sunshine, air and water are the vital elements to the human. This study investigated the insolation and solar radiation in Kaohsiung city. Solar radiation on the horizontal and declined plane was calculated. Sun shadow model for urban buildings was constructed for computing accumulated sunshining hours. Horizontal and vertical building shadows were displayed in ArcGIS ¡V the GIS software. Raster-based data model was used to analyze the effect of sun shadow shading by neighbour buildings. And the effect of shadow shading for solar water heater was also investigated. According to the results, minor installation error of orientation and decline angles of solar panel will not cause major energy loss. And the distance between the buildings¡Bthe height difference and the orientation between buildings are most important factors which affect optimal installation location of the solar water heater. If there are buildings located to the south, southeast and southwest, and the stories difference between buildings is over three, the installing location should be moved toward north. If buildings are next to each others and the variation of height is large, the efficient of receiving solar radiation will be deteriorated. The larger is the distance between buildings, the better the energy received.

We present methods for incorporating bubbles into a photorealistc fluid simulation. Previous methods of fluid simulation in computer graphics do not include bubbles. Our system automatically creates bubbles, which are simulated on top of the fluid simulation. These bubbles are approximated by spheres and are rendered with the fluid to appear as one continuous surface. This enhances the overall realism of the appearance of a splashing fluid for computer graphics. Our methods leverage the particle level set representation of the fluid surface. We create bubbles from escaped marker particles from the outside to the inside. These marker particles might represent air that has been trapped within the fluid surface. Further, we detect when air is trapped in the fluid and create bubbles within this space. This gives the impression that the air pocket has become bubbles and is an inexpensive way to simulate the air trapped in air pockets. The results of the simulation are rendered with a raytracer that includes caustics. This allows the creation of photorealistic images. These images support our position that the simple addition of bubbles included in a fluid simulation creates results that are much more true to life.

<p>Då scenkomplexitet och ett högre antal ljuskällor blir vanligare inom spel har ett behov av algortimer för att hantera dessa scener, med bra prestanda, uppståt. En allt vanligare algoritm för detta är Deferred Shading. Rapporten utvärderar två olika metoder för <em>Deferred Shading</em> (traditionell <em>Deferred Shading</em> och <em>Light pre-pass rendering</em>).</p>

This thesis analyzes the feasibility of having an integrated wind and solar farm to optimize the use of land resources and capital investment by evaluating the effect that wind turbine shadows have on the area surrounding them. Two methods are used to predict shadow impact. The first method is based on the traditional textbook “Clear Sky” equations, which have maximum sensitivity to shadows because the method considers every day to be a perfect day. The second method uses measured global-horizontal and diffuse-horizontal solar radiation in units of W/m2, which take into account the true variations of daily conditions. The calculations are performed for 1 square meter surfaces, over different assumed areas of a wind power plant, for every second of the day. For purposes of shadow calculations, the tip-top height (i.e., tower height plus blade length) is used. All calculations are performed with the specifications of a GE 1.5 MW wind turbine, which is the most commonly used wind turbine in USA. / text