7,455 research outputs found
Penumbra maps: approximate soft shadows in real-time
Journal ArticleGenerating soft shadows quickly is difficult. Few techniques have enough flexibility to interactively render soft shadows in scenes with arbitrarily complex occluders and receivers. This paper introduces the penumbra map, which extends current shadow map techniques to interactively approximate soft shadows. Using object silhouette edges, as seen from the center of an area light, a map is generated containing approximate penumbral regions. Rendering requires two lookups, one into each the penumbra and shadow maps. Penumbra maps allow arbitrary dynamic models to easily shadow themselves and other nearby complex objects with plausible penumbrae
Penumbra maps
technical reportGenerating soft shadows quickly is difficult. Few techniques have enough flexibility to interactively render soft shadows in scenes with arbitrarily complex occluders and receivers. This paper introduces the penumbra map, which extends current shadow map techniques to interactively approximate soft shadows. Using object silhouette edges, as seen from the center of an area light, a map is generated containing approximate penumbral regions. Rendering requires two lookups, one into each the penumbra and shadow maps. Penumbra maps allow arbitrary dynamic models to easily shadow themselves and other nearby complex objects with plausible penumbrae
An Upper Bound on the Average Size of Silhouettes
It is a widely observed phenomenon in computer graphics that the size of the
silhouette of a polyhedron is much smaller than the size of the whole
polyhedron. This paper provides, for the first time, theoretical evidence
supporting this for a large class of objects, namely for polyhedra that
approximate surfaces in some reasonable way; the surfaces may be non-convex and
non-differentiable and they may have boundaries. We prove that such polyhedra
have silhouettes of expected size where the average is taken over
all points of view and n is the complexity of the polyhedron
Multiple object tracking using a neural cost function
This paper presents a new approach to the tracking of multiple objects in CCTV surveillance using a combination of simple neural cost functions based on Self-Organizing Maps, and a greedy assignment algorithm. Using a reference standard data set and an exhaustive search algorithm for benchmarking, we show that the cost function plays the most significant role in realizing high levels of performance. The neural cost function’s context-sensitive treatment of appearance, change of appearance and trajectory yield better tracking than a simple, explicitly designed cost function. The algorithm matches 98.8% of objects to within 15 pixels
Drone Shadow Tracking
Aerial videos taken by a drone not too far above the surface may contain the
drone's shadow projected on the scene. This deteriorates the aesthetic quality
of videos. With the presence of other shadows, shadow removal cannot be
directly applied, and the shadow of the drone must be tracked. Tracking a
drone's shadow in a video is, however, challenging. The varying size, shape,
change of orientation and drone altitude pose difficulties. The shadow can also
easily disappear over dark areas. However, a shadow has specific properties
that can be leveraged, besides its geometric shape. In this paper, we
incorporate knowledge of the shadow's physical properties, in the form of
shadow detection masks, into a correlation-based tracking algorithm. We capture
a test set of aerial videos taken with different settings and compare our
results to those of a state-of-the-art tracking algorithm.Comment: 5 pages, 4 figure
GENERATION OF FORESTS ON TERRAIN WITH DYNAMIC LIGHTING AND SHADOWING
The purpose of this research project is to exhibit an efficient method of creating dynamic lighting and shadowing for the generation of forests on terrain. In this research project, I use textures which contain images of trees from a bird’s eye view in order to create a high scale forest. Furthermore, by manipulating the transparency and color of the textures according to the algorithmic calculations of light and shadow on terrain, I provide the functionality of dynamic lighting and shadowing. Finally, by analyzing the OpenGL pipeline, I design my code in order to allow efficient rendering of the forest
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