Authors:
Claus B. Madsen
and
Michael Nielsen
Affiliation:
Computer Vision and Media Technology Lab, Aalborg University, Denmark
Keyword(s):
Augmented Reality, illumination estimation, rendering, shadow detection, shadow rendering.
Related
Ontology
Subjects/Areas/Topics:
Augmented, Mixed and Virtual Environments
;
Computer Vision, Visualization and Computer Graphics
;
Image-Based Rendering
;
Interactive Environments
;
Lighting and Appearance
;
Rendering
;
Rendering Algorithms
;
Shadows, Translucency and Visibility
Abstract:
The main problem area for Augmented Reality is ensuring that the illumination of the virtual objects is continuously consistent with the illumination in the real scene. State of the art in the area typically requires the real scene illumination conditions to be captured as a High Dynamic Range environment map. The environment map is then used for shading and shadowing. Handling the real and the virtual shadows and their interaction is the single most difficult aspect. This paper presents a completely different approach to determining the illumination conditions in the real scene. Based on an assumption that the scene is outdoor we automatically detect shadows in the image and use this information to determine the ratio of sky irradiance to sun irradiance. We then present how to convert this information into radiance levels for both the sky and the sun. When combined with a computation of the Sun’s position based on date, time and information about position on the Earth, we arrive at
a full illumination model applicable for rendering virtual objects into real scenes.
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