Download presentation

Presentation is loading. Please wait.

Published byDeshawn Tony Modified over 2 years ago

1
Corrections to the Surface Area Metric with Respect to Mail-Boxing Warren Hunt

2
Introduction The Surface Area Metric is the most common cost metric for acceleration structures The metric doesn’t account for the effects of mail-boxing (when present)

3
What is Mail-boxing? Optimization for partitioning based acceleration structures Attempts to avoid multiple intersection tests between the same ray/object pair

4
Contribution Overview Present a correction to the surface area metric for mail-boxing – Extremely simple to implement – Significant reduction in intersection tests – Modest improvement in performance – Improves the effectiveness of mail-boxing

5
The Surface Area Metric Cost(s) = P(s left )Cost(s left ) + P(s right )Cost(s right ) P is the probability function (based on surface area) During build, cost is estimated by the number of objects overlapping each side – Mail-boxing changes this cost!

6
Corrected Surface Area Metric Cost(s) = P(s left )*Cost(s left ) + P(s right )*Cost(s right ) - P(s right^left )*Cost(s right^left ) P(s left^right ) is the probability that a ray strikes both sides of the split – Partition is convex, use ratio of surface areas Cost(s left^right ) is the number of objects that occur on both sides of the split

7
Effects of the Modification Fundamentally changes the effectiveness of kd-trees when using mail-boxing – Allows splits that the SAH wouldn’t previously allow – Allows mail-boxing to fully address the integral duplication problem in kd-trees (explained shortly!)

8
Example: Abutted Cells 1 1 1 KD-Tree Split Plane Left BVRight BV

9
Example: Overlapping Cells Left BVRight BV 1 1-Δ2Δ KD-Tree Split Planes – Original SAM wouldn’t allow either of these splits! – Detailed explanation in the paper KD-Tree Split Plane

10
Results ~30% reduction in intersection tests when compared to the uncorrected SAM ~5% reduction in overall render-time ~5% increase in traversal steps Results are fairly consistent between off-line and real-time ray-tracers

11
Specific Results Teaser Using an interactive ray-tracer FForest020IntersectionsTimeSteps Original 29.43 M3.359 s96.10 M Modified 21.60 M3.006 s99.54 M Difference -27%-10.2%+3.58%

12
Conclusions Presented a correction to the surface area metric for mail-boxing – Extremely simple to implement – Significant reduction in intersection tests – Modest improvement in performance – Improves the effectiveness of mail-boxing

13
Questions?

14
Advertisement! I’m graduating this fall and looking for a job! – Formally as of now – Willing to relocate etc.

15
Perspective Questions?

Similar presentations

Presentation is loading. Please wait....

OK

CIS 350 – I Game Programming Instructor: Rolf Lakaemper.

CIS 350 – I Game Programming Instructor: Rolf Lakaemper.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on vegetarian and non vegetarian buffet Ppt on applied operational research pdf Ppt on tourism in karnataka Ppt on any one mathematician Ppt on object-oriented concepts in java with examples Ppt on appropriate climate responsive technologies for inclusive growth and sustainable development Ppt on rainwater harvesting Ppt on porter's five forces model examples Ppt on best practices in hr Ppt on coalition government in england