| 1. |
- Akenine-Möller, Tomas, et al.
(author)
-
Simple Environment Map Filtering Using Ray Cones and Ray Differentials
- 2019
-
In: Ray Tracing Gems : High-Quality and Real-Time Rendering with DXR and Other APIs - High-Quality and Real-Time Rendering with DXR and Other APIs. - Berkeley, CA : Apress. - 9781484244265 - 9781484244272 ; , s. 347-351
-
Book chapter (peer-reviewed)abstract
- We describe simple methods for how to filter environment maps using ray cones and ray differentials in a ray tracing engine.
|
|
| 2. |
- Akenine-Möller, Tomas, et al.
(author)
-
Texture Level of Detail Strategies for Real-Time Ray Tracing
- 2019
-
In: Ray Tracing Gems : High-Quality and Real-Time Rendering with DXR and Other APIs - High-Quality and Real-Time Rendering with DXR and Other APIs. - Berkeley, CA : Apress. - 9781484244265 - 9781484244272 ; , s. 321-345
-
Book chapter (peer-reviewed)abstract
- Unlike rasterization, where one can rely on pixel quad partial derivatives, an alternative approach must be taken for filtered texturing during ray tracing. We describe two methods for computing texture level of detail for ray tracing. The first approach uses ray differentials, which is a general solution that gives high-quality results. It is rather expensive in terms of computations and ray storage, however. The second method builds on ray cone tracing and uses a single trilinear lookup, a small amount of ray storage, and fewer computations than ray differentials. We explain how ray differentials can be implemented within DirectX Raytracing (DXR) and how to combine them with a G-buffer pass for primary visibility. We present a new method to compute barycentric differentials. In addition, we give previously unpublished details about ray cones and provide a thorough comparison with bilinearly filtered mip level 0, which we consider as a base method.
|
|
| 3. |
- Haines, Eric, et al.
(author)
-
Precision Improvements for Ray/Sphere Intersection
- 2019
-
In: Ray Tracing Gems : High-Quality and Real-Time Rendering with DXR and Other APIs - High-Quality and Real-Time Rendering with DXR and Other APIs. - Berkeley, CA : Apress. - 9781484244272 - 9781484244265 ; , s. 87-94
-
Book chapter (peer-reviewed)abstract
- The traditional quadratic formula is often presented as the way to compute the intersection of a ray with a sphere. While mathematically correct, this factorization can be numerically unstable when using floating-point arithmetic. We give two little-known reformulations and show how each can improve precision.
|
|
| 4. |
- Shirley, Peter, et al.
(author)
-
What is a Ray?
- 2019
-
In: Ray Tracing Gems : High-Quality and Real-Time Rendering with DXR and Other APIs - High-Quality and Real-Time Rendering with DXR and Other APIs. - Berkeley, CA : Apress. - 9781484244272 - 9781484244265 ; , s. 15-19
-
Book chapter (peer-reviewed)abstract
- We define a ray, show how to use ray intervals, and demonstrate how to specify a ray using DirectX Raytracing (DXR).
|
|
| 5. |
- Aila, Timo, et al.
(author)
-
A Hierarchical Shadow Volume Algorithm
- 2004
-
In: Graphics Hardware. - 3905673150 ; , s. 15-23
-
Conference paper (peer-reviewed)abstract
- The shadow volume algorithm is a popular technique for real-time shadow generation using graphics hardware. Its major disadvantage is that it is inherently fillrate-limited, as the performance is inversely proportional to the area of the projected shadow volumes. We present a new algorithm that reduces the shadow volume rasterization work significantly. With our algorithm, the amount of per-pixel processing becomes proportional to the screenspace length of the visible shadow boundary instead of the projected area. The first stage of the algorithm finds 8×8 pixel tiles, whose 3D bounding boxes are either completely inside or outside the shadow volume. After that, the second stage performs per-pixel computations only for the potential shadow boundary tiles. We outline a twopass implementation, and also describe an efficient single-pass hardware architecture, in which the two stages are separated using a delay stream. The only modification required in applications is a new pair of calls for marking the beginning and end of a shadow volume. In our test scenes, the algorithm processes up to 11.5 times fewer pixels compared to current state-of-the-art methods, while reducing the external video memory bandwidth by a factor of up to 17.1.
|
|
| 6. |
- Akenine-Möller, Tomas, 1970
(author)
-
An Extremely Inexpensive Multisampling Scheme
- 2003
-
Reports (other academic/artistic)abstract
- We present a new sampling scheme for low-cost multisampling rasterization. The scheme builds upon sample sharing and the N-rooks sample scheme, and it achieves at most two shades in between fully outside and fully inside. Also, the slightly irregular pattern helps disguising aliasing effects. A simple visual evaluation shows that our new scheme gives similar quality to that of the Quincunx scheme. More importantly, our scheme uses only 1.25 samples on average per pixel, while Quincunx and FLIPQUAD uses 2 samples. As a consequence, our new scheme uses 62:5 percent of the memory and memory bandwidth as compared to Quincunx and FLIPQUAD.
|
|
| 7. |
- Akenine-Möller, Tomas, et al.
(author)
-
Approximate Soft Shadows on Arbitrary Surfaces using Penumbra Wedges
- 2002
-
In: EGRW '02 Proceedings of the 13th Eurographics workshop on Rendering. - 1581135343 ; , s. 297-306
-
Conference paper (peer-reviewed)abstract
- Shadow generation has been subject to serious investigation in computer graphics, and many clever algorithms have been suggested. However, previous algorithms cannot render high quality soft shadows onto arbitrary, animated objects in real time. Pursuing this goal, we present a new soft shadow algorithm that extends the standard shadow volume algorithm by replacing each shadow quadrilateral with a new primitive, called the penumbra wedge. For each silhouette edge as seen from the light source, a penumbra wedge is created that approximately models the penumbra volume that this edge gives rise to. Together the penumbra wedges can render images that often are remarkably close to more precisely rendered soft shadows. Furthermore, our new primitive is designed so that it can be rasterized efficiently. Many real-time algorithms can only use planes as shadow receivers, while ours can handle arbitrary shadow receivers. The proposed algorithm can be of great value to, e.g., 3D computer games, especially since it is highly likely that this algorithm can be implemented on programmable graphics hardware coming out within the next year, and because games often prefer perceptually convincing shadows.
|
|
| 8. |
- Akenine-Möller, Tomas, et al.
(author)
-
Conservative and tiled rasterization using a modified triangle setup
- 2005
-
In: Journal of Graphics Tools. - 2151-237X. ; 10:3, s. 1-8
-
Journal article (peer-reviewed)abstract
- Several algorithms that use graphics hardware to accelerate processing require conservative rasterization in order to function correctly. Conservative rasterization stands for either overestimating or underestimating the size of the triangles. Overestimation is carried out by including all pixels that are at least partially overlapped by the triangle, whereas underestimation includes only the pixels that are fully inside the triangle. No or few algorithms for conservative rasterization have been described in the literature, and current hardware does not explicitly support it. Therefore, we present a simple algorithm, which requires only a small modification to the triangle set-up when edge functions are used. Furthermore, the same algorithm can be used for tiled rasterization, where all pixels in a tile (e.g., 8 × 8 pixels) are visited before moving to the next tile.
|
|
| 9. |
- Akenine-Möller, Tomas, et al.
(author)
-
Efficient Depth of Field Rasterization Using a Tile Test Based on Half-Space Culling
- 2012
-
In: Computer Graphics Forum. - : Wiley. - 1467-8659 .- 0167-7055. ; 31:1, s. 3-18
-
Journal article (peer-reviewed)abstract
- For depth of field (DOF) rasterization, it is often desired to have an efficient tile versus triangle test, which can conservatively compute which samples on the lens that need to execute the sample-in-triangle test. We present a novel test for this, which is optimal in the sense that the region on the lens cannot be further reduced. Our test is based on removing half-space regions of the (u, v) -space on the lens, from where the triangle definitely cannot be seen through a tile of pixels. We find the intersection of all such regions exactly, and the resulting region can be used to reduce the number of sample-in-triangle tests that need to be performed. Our main contribution is that the theory we develop provides a limit for how efficient a practical tile versus defocused triangle test ever can become. To verify our work, we also develop a conceptual implementation for DOF rasterization based on our new theory. We show that the number of arithmetic operations involved in the rasterization process can be reduced. More importantly, with a tile test, multi-sampling anti-aliasing can be used which may reduce shader executions and the related memory bandwidth usage substantially. In general, this can be translated to a performance increase and/or power savings.
|
|
| 10. |
- Akenine-Möller, Tomas, et al.
(author)
-
Graphics for the Masses: A Hardware Rasterization Architecture for Mobile Phones
- 2003
-
In: ACM Transactions on Graphics. - : Association for Computing Machinery (ACM). - 1557-7368 .- 0730-0301. ; 22:3, s. 801-808
-
Conference paper (peer-reviewed)abstract
- The mobile phone is one of the most widespread devices with rendering capabilities. Those capabilities have been very limited because the resources on such devices are extremely scarce; small amounts of memory, little bandwidth, little chip area dedicated for special purposes, and limited power consumption. The small display resolutions present a further challenge; the angle subtended by a pixel is relatively large, and therefore reasonably high quality rendering is needed to generate high fidelity images.To increase the mobile rendering capabilities, we propose a new hardware architecture for rasterizing textured triangles. Our architecture focuses on saving memory bandwidth, since an external memory access typically is one of the most energy-consuming operations, and because mobile phones need to use as little power as possible. Therefore, our system includes three new key innovations: 1) an inexpensive multisampling scheme that gives relatively high quality at the same cost of previous inexpensive schemes, II) a texture minification system, including texture compression, which gives quality relatively close to trilinear mipmapping at the cost of 1.33 32-bit memory accesses on average, III) a scanline-based culling scheme that avoids a significant amount of z-buffer reads, and that only requires one context. Software simulations show that these three innovations together significantly reduce the memory bandwidth. and thus also the power consumption.
|
|
