Software package for testing three-dimensional shape measurement methods using structured lighting

This work aims at creating a universal software package for the development and testing of triangulation methods using structured lighting for measuring the three-dimensional geometry of objects in difficult ambient lighting conditions. As a result, a software package meeting the stated requirements is created. Lighting is based on the Fong model. A method for preloading objects is implemented to optimize the operation of the software package. An accelerated method for creating shadow maps is proposed and implemented. The developed software package is shown to successfully perform all required functions.

Shadow Map Construction using 2D Homography

In computer graphic applications, shadow plays an important role in expressing the reality of an object. Shadow shows the relationship between objects in space. Shadow map is one of the methods that meet the demand simplification in implementation and speed. This method made an alias around the border of shading. In this paper, we proposed a method using a 2D homography transformation. This method reduces the unused area in the shadow maps, so it can help to minimize the alias. With the experiment in VanMieu Tran Bien- a Vietnamese historical place, we compare the method with others.

Interactive 3D Time-Integrated Solar Shadow Maps

<p><strong>Abstract.</strong> Urban areas are characterized by a complex topography of buildings, terrain, vegetation and temporary structures, which, depending on their extent, geometry, geographic location and daytime, cast shadow on their surroundings. Given the importance of sunlight for various groups of interest and tasks, we argue that a comprehensive, accessible, usable and intuitive way of predicting its availability for specific usage contexts is surprisingly lacking. In our research, we are investigating how to improve the visual communication of urban solar conditions for various real-world usage scenarios like having a coffee in the sun, parking a car in the shade, or taking a photograph of a particular building in a favorable light. All of these activities take place over a period of time, not in a temporal instant, causing solar shadows to move. Hence, a static representation of the light situation at a distinct point in time, such as offered by available 3D urban maps or GIS systems, is often not sufficient for planning above mentioned recreational or professional activities.</p><p>This factor is incorporated in our system by integrating shadow motion into a shadow map that covers arbitrary timeframes within a given day (Figure 1). Shadows are accumulated by projecting shadow maps from astronomically precise sun positions spanning over the defined timeframe. The number of sampling points directly influences the quality and speed of the rendering. All provided figures currently sample and integrate nine different sun positions.</p><p>Using our system, questions in a manner of “Given a specific point in space, at which time will this point be in sun/shade again” can be answered. E.g., one would like to spend time in the sun at a specific Viennese “Kaffeehaus” (coffee place), from which time on (and for how long) will this space be sunlit (Figure 2). In the future, this process might even be automated.</p>