in Embree & OSPRay Christiaan Gribble SURVICE Engineering - - PowerPoint PPT Presentation

▶
in embree ospray
SMART_READER_LITE
LIVE PREVIEW

in Embree & OSPRay Christiaan Gribble SURVICE Engineering - - PowerPoint PPT Presentation

Aug 11, 2023 106 likes •627 views

Realizing Multi-Hit Ray Tracing in Embree & OSPRay Christiaan Gribble SURVICE Engineering Intel HPC Developer Conference 12 November 2016 Take-home messages Multi-hit ray traversal Enables a new class of ray-based rendering &

slide-1
SLIDE 1

Realizing Multi-Hit Ray Tracing in Embree & OSPRay

Christiaan Gribble

SURVICE Engineering Intel HPC Developer Conference 12 November 2016

slide-2
SLIDE 2

Take-home messages

  • Multi-hit ray traversal

Enables a new class of ray-based rendering & simulation applications

  • Embree permits efficient implementation
  • OSPRay permits easy integration

2

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-3
SLIDE 3

Take-home messages

  • Multi-hit ray traversal
  • Embree permits efficient implementation

Intersection filter functions enable user-level implementation

  • f state-of-the-art multi-hit ray traversal techniques
  • OSPRay permits easy integration

3

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-4
SLIDE 4

Take-home messages

  • Multi-hit ray traversal
  • Embree permits efficient implementation
  • OSPRay permits easy integration

Supports scalable, high performance visual analysis tools across optical & non-optical domains

4

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-5
SLIDE 5

Acknowledgements

  • SURVICE
  • Joe Rosenthal
  • Mark Butkiewicz
  • Intel
  • Jeff Amstutz
  • Ingo Wald
  • Jim Jeffers

5

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-6
SLIDE 6

Overview

slide-7
SLIDE 7

Interval computation

Optical rendering

7

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-8
SLIDE 8

Interval computation

Optical rendering

8

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-9
SLIDE 9

Interval computation

Optical rendering Non-optical rendering

9

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-10
SLIDE 10

Interval computation

Optical rendering Non-optical rendering

10

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-11
SLIDE 11

Non-optical rendering

Interval computation

11

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-12
SLIDE 12

Non-optical rendering

Interval computation

12

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-13
SLIDE 13

Non-optical rendering Interval computation

Interval computation

13

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-14
SLIDE 14

Interval computation

  • Difficult or impossible
  • Epsilon hacks
  • Missed/repeated intersections
  • Performance impacts

14

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-15
SLIDE 15

Interval computation

  • Difficult or impossible
  • Performance impacts
  • Traversal restart
  • Operational overhead

15

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-16
SLIDE 16

Interval computation

  • Difficult or impossible
  • Performance impacts

Is there a better solution?

16

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-17
SLIDE 17

Multi-hit ray traversal

  • Which primitives are intersected?
  • One or more, & possibly all
  • Ordered by t-value along ray
  • Possible applications
  • GNK14
  • AGGW15
  • Gri16, GWA16

17

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-18
SLIDE 18

Multi-hit ray traversal

  • Which primitives are intersected?
  • Possible applications
  • Transparent rendering
  • Alpha textures
  • GNK14
  • AGGW15
  • Gri16, GWA16

18

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-19
SLIDE 19

Multi-hit ray traversal

  • Which primitives are intersected?
  • Possible applications
  • GNK14
  • Spatial partitioning
  • Two algorithms: naive, buffered
  • AGGW15
  • Gri16, GWA16

19

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-20
SLIDE 20

Multi-hit ray traversal

  • Which primitives are intersected?
  • Possible applications
  • GNK14
  • AGGW15
  • Object partitioning
  • User-level implementation mechanisms
  • Gri16, GWA16

20

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-21
SLIDE 21

Multi-hit ray traversal

  • Which primitives are intersected?
  • Possible applications
  • GNK14
  • AGGW15
  • Gri16, GWA16
  • Enable early-exit in BVH
  • Implement in Embree & OSPRay

21

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-22
SLIDE 22

Implementation

slide-23
SLIDE 23

Mechanisms

  • Direct implementation
  • Kernels specific to multi-hit
  • Runs counter to our goal
  • Intersection callbacks
  • Traversal callbacks
  • Reference implementation

23

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-24
SLIDE 24

Mechanisms

  • Direct implementation
  • Intersection callbacks
  • Invoked on valid ray/primitive intersection
  • User accepts/rejects hit
  • Traversal callbacks
  • Reference implementation

24

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-25
SLIDE 25

Mechanisms

  • Direct implementation
  • Intersection callbacks
  • Traversal callbacks
  • Invoked on ray/node interaction
  • Two variants: every-node, leaf-node
  • Reference implementation

25

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-26
SLIDE 26

Mechanisms

  • Direct implementation
  • Intersection callbacks
  • Traversal callbacks
  • Reference implementation
  • Supports callback mechanisms
  • Opts for clarity & simplicity

26

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay

http://www.rtvtk.org/~cgribble/research/mhBVH/

slide-27
SLIDE 27

Embree implementation

  • Intersection filters
  • Compatible with mainline developments
  • v2.10.0+ – enables node-culling
  • Assumptions
  • Full source code available

27

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-28
SLIDE 28

Embree implementation

  • Intersection filters
  • Assumptions
  • Nquery known a priori
  • Preallocated hit data buffer
  • Initial value beyond range
  • Full source code available

28

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-29
SLIDE 29

Embree implementation

  • Intersection filters
  • Assumptions
  • Full source code available
  • Apache License, v2.0
  • Public git repository

29

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay

http://www.rtvtk.org/~cgribble/research/ospMultiHit/

slide-30
SLIDE 30

Scalar implementation

static void collectIntersectionsFilter(void* /* unused */, RTCRay& _ray) { 0 // Find index at which to store candidate intersection 1 uint idx = Nquery; 2 while (idx > 0 && ray.tfar < hits[idx-1].tval) 3 { 4 hits[idx] = hits[idx-1]; 5 --idx; 6 }

30

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-31
SLIDE 31

Scalar implementation

7 // Store intersection, possibly beyond index of the 8 // N ≤ Nquery closest intersections (i.e., at 9 // idx = Nquery) 10 HitData& hit = hits[idx]; 11 hit.geomID = ray.geomID; 12 hit.primID = ray.primID; 13 hit.tval = ray.tfar; 14 hit.Ng = ray.Ng; 15 16 // Update number of intersections identified so far 17 ray.nhits += (ray.nhits < Nquery ? 1 : 0);

31

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-32
SLIDE 32

Scalar implementation

17 if (ray.nhits < Nquery) 18 { 19 // Reject intersection to continue traversal with 20 // incoming ray interval, as in previous work 21 // [Amstutz et al. 2015] 22 ray.geomID = RTC_INVALID_GEOMETRY_ID; 23 return; 24 }

32

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-33
SLIDE 33

Scalar implementation

25 // Induce node culling 26 // Trick: set ray.tfar to farthest value among the 27 // N = Nquery intersections identified so far 28 // and (implicitly) accept intersection with 29 // modified ray interval 30 ray.tfar = hits[Nquery-1].tval; 31 }

33

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-34
SLIDE 34

Results

slide-35
SLIDE 35

Performance – tests

  • Find-first-intersection
  • First-hit v. multi-hit variants
  • Isolates multi-hit overhead
  • Find-all-intersections
  • Find-some-intersections

35

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-36
SLIDE 36

Performance – tests

  • Find-first-intersection
  • Find-all-intersections
  • Naive v. node culling multi-hit
  • Bounds performance expectations
  • Find-some-intersections

36

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-37
SLIDE 37

Performance – tests

  • Find-first-intersection
  • Find-all-intersections
  • Find-some-intersections
  • Naive v. node culling multi-hit
  • Demonstrates in situ performance

37

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-38
SLIDE 38

Performance – scenes

sibe 80K tris fair 174K tris conf 282K tris truck 426K tris tank 1.0M tris hball 2.8M tris sanm 10.5M tris pplant 12.7M tris

38

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-39
SLIDE 39

Performance – truck scene

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 10% 1 30% 70% all

Mhps

+4.60x +1.64x +1.08x 0.96x 0.97x naive culling

39

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-40
SLIDE 40

Performance – truck scene

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 10% 1 30% 70% all

Mhps

+4.60x +1.64x +1.08x 0.96x 0.97x naive culling

40

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-41
SLIDE 41

Performance – truck scene

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 10% 1 30% 70% all

Mhps

+4.60x +1.64x +1.08x 0.96x 0.97x naive culling

41

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-42
SLIDE 42

Limitations

  • Number of hits specified a priori
  • Too few – incorrect
  • Too many – wasteful
  • C++ templates?
  • Ordered BVH traversal [WAB16]
  • Spatial partitioning [GNK14]

42

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-43
SLIDE 43

Limitations

  • Number of hits specified a priori
  • Ordered BVH traversal [WAB16]
  • Enables early-exit
  • No dynamic allocation
  • Requires new traversal kernels
  • Spatial partitioning [GNK14]

43

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-44
SLIDE 44

Limitations

  • Number of hits specified a priori
  • Ordered BVH traversal [WAB16]
  • Spatial partitioning [GNK14]
  • Enables early-exit
  • No dynamic allocation
  • Requires user-defined geometry

44

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-45
SLIDE 45

Demonstrations

Engineering CAD visualization Vulnerability analysis

45

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-46
SLIDE 46

Wrap-up

slide-47
SLIDE 47

Take-home messages

  • Multi-hit ray traversal

Enables a new class of ray-based rendering & simulation applications

  • Embree permits efficient implementation
  • OSPRay permits easy integration

47

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-48
SLIDE 48

Take-home messages

  • Multi-hit ray traversal
  • Embree permits efficient implementation

Intersection filter functions enable user-level implementation

  • f state-of-the-art multi-hit ray traversal techniques
  • OSPRay permits easy integration

48

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-49
SLIDE 49

Take-home messages

  • Multi-hit ray traversal
  • Embree permits efficient implementation
  • OSPRay permits easy integration

Supports scalable, high performance visual analysis tools across optical & non-optical applications

49

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-50
SLIDE 50

Key references

[AGGW15] Amstutz, J., Gribble, C., Gunther, J., & Wald, I. (2015) An evaluation of multi-hit ray traversal in a BVH using existing first-hit/any-hit kernels. Journal

  • f Computer Graphics Techniques, 4(4):72—90.

[GNK14] Gribble, C., Naveros, A., & Kerzner, E. (2014) Multi-hit ray traversal. Journal of Computer Graphics Techniques, 3(1):1—17. [Gri16] Gribble, C. (2016) Node culling multi-hit BVH traversal. Eurographics Symposium

  • n Rendering. doi:10.2312/sre.20161213

[GWA16] Gribble, C., Wald, I., & Amstutz, J. (2016) Implementing node culling multi-hit BVH traversal in Embree. Journal of Computer Graphics Techniques, 5(4):29—35.

50

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay
slide-51
SLIDE 51

Contact information

Address

Applied Technology Operation SURVICE Engineering 4695 Millennium Drive Belcamp, MD 21017

E-mail

christiaan.gribble@survice.com

Web

http://www.survice.com/employees/~cgribble/

51

  • C. Gribble, Realizing Multi-Hit Ray Tracing in Embree & OSPRay