Illumination of image-based objects

Wong, Tien‐Tsin; Heng, Pheng‐Ann; Or, Siu-Hang; Ng, Wai-Yin

doi:10.1002/(sici)1099-1778(199807/09)9:3<113::aid-vis183>3.0.co;2-4

Cited by 6 publications

(4 citation statements)

References 10 publications

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“…This is especially important when illumination is included. A few attempts have been made in our previous work [23,22,24]. There is still much work to do in using the image-based object as a basic rendering primitive in virtual reality, and our work is only a preliminary step in this direction.…”

Section: Conclusion and Future Directionmentioning

confidence: 99%

Navigation and Illumination Control for Image-Based VR

Wong¹,

Heng²

2000

IJVR

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Simulation sickness in virtual reality applications is usually due to the non-realtime display of virtual environment. Realtime display of arbitrarily complex scene is a hard problem in traditional geometry-based computer graphics. Image-based modeling and rendering (IBMR) provides an alternative approach whose rendering time complexity is independent of scene complexity. However, due to the lack of geometrical information, capabilities that are obvious to geometry-based virtual reality become difficult problems in image-based virtual reality. In this paper we discuss how two fundamental capabilities, navigation and illumination control, can be achieved in image-based virtual reality applications. To navigate an image-based scene, we need to know where pixels should be moved to and how to solve their visibility. While correspondences or optical flows can answer the former question, the visibility is more difficult to answer, as depth information may not be available. Deriving from epipolar geometry, we propose a triangle-based visibility-ordering algorithm, which can correctly resolve the occlusion without depth information. To control the illumination, we propose a new image representation that not just allows navigation but also re-rendering under various illuminations. By treating each image pixel as an ordinary surface element, we measure the apparent BRDF of each pixel from reference images. By manipulating these apparent pixel BRDFs, we are able to re-render (change the illumination of the scene in an image) without any geometry information. Even shadows can be correctly re-rendered.

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Section: Conclusion and Future Directionmentioning

confidence: 99%

Navigation and Illumination Control for Image-Based VR

Wong¹,

Heng²

2000

IJVR

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“…Employing wavelets with their limited support allows a significant reduction in evaluation time as well as a means of estimating truncation error. Wong et al 16 presented an image-based method to re-illuminate objects by storing an effective BRDF on the spherical harmonic basis with coefficients obtained from multiple views of the object.…”

Section: Linear Brdf Approximationsmentioning

confidence: 99%

Frequency space techniques for BRDF shading

Scoggins

Machiraju

2004

Targets and Backgrounds X: Characterization and Representation

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The Bi-directional Reflectance Distribution Function (BRDF) is a general way to represent reflection from surfaces. However, even when ignoring variations in location and wavelength, the BRDF is still a 4-dimensional function and the number of BRDF samples necessary for direct utilization can impose severe computational requirements. To address these and other problems, analytical BRDF equations have been developed for computer image simulations. Limitations remain since they may be empirical, appropriate only for specific surfaces, or require difficult-to-obtain physical parameters. BRDF shading based on signal processing methods has recently been presented in computer graphics that projects any BRDF onto an orthogonal basis set and then employs a truncated linear series for shading with controlled accuracy. This paper presents an overview of BRDF shading and frequency-space representations using orthogonal polynomials as basis functions. Techniques are then described that utilize the resulting linear shading equations to factor lighting and geometry components of a scene for image-based re-lighting. Statistical properties of images may then be partially computed for fixed views in a pre-process phase and employed to rapidly compute view properties for arbitrary lighting distributions and different BRDFs. Techniques are also described for producing correct blended BRDFS aimed at level-of-detail frequency-space shading.

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“…To control the illumination, Wong et al treated each image pixel as an ordinary surface element and measures its apparent BRDF from reference images. By manipulating these apparent pixel BRDFs, they were able to rerender (change the illumination of the scene in an image) without any geometry information [30]. Figure 2 is an example.…”

Section: Computer Graphics In Academiamentioning

confidence: 99%

Computer graphics around the world

Pan

Heng

Lau

2000

SIGGRAPH Comput. Graph.

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Computer graphics has evolved to become an important discipline in both academia and industry, and an enabling technology for a broad variety of applications such as engineering (CAD, CAE and CAM), GIS, publishing and office applications. It can no longer be regarded as a confined discipline devoted solely to graphics standards or traditional techniques of 3D representations and rendering. The influence of computer graphics can be felt in almost all of today's key industrial areas, wherever computers are employed.Computer graphics has been a subject of interest in Hong Kong in recent years. Overviews of activities in China were presented in [18, 19] and in a special journal on computer graphics [20]. However, computer graphics activities in Hong Kong were not included in these materials, since all the papers mentioned above were published before July 1, 1997, when Hong Kong returned to China. Therefore, we present this article as a supplementary part to the two overviews, and try to give people an overall picture of computer graphics activities in China.

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Illumination of image-based objects

Cited by 6 publications

References 10 publications

Navigation and Illumination Control for Image-Based VR

Navigation and Illumination Control for Image-Based VR

Frequency space techniques for BRDF shading

Computer graphics around the world

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