progressive lightcuts for gpu

Progressive Lightcuts for GPU

Tomáš DavidovičI. Georgiev, P. Slusallek

Saarland University, Intel VCI

T. DavidovičProgressive Lightcuts for GPU

Direct illumination


VPL Rendering


VPL Rendering

Bruteforce: 11s


VPL Rendering

Lightcuts: 2s


VPL Rendering


Lightcuts


Lightcuts – progressive #1



Lightcuts, 20s Reference



Lightcuts, 20s Bruteforce, 2400s


Lightcuts – Heapless

Lightcuts, 10s Cut sizeHeapless


Lightcuts – clamping

Unclamped


Lightcuts – clamping

Clamped


Clamping


Clamping

Contrib. ≈ k / (d^2)


Clamping

Contrib. ≈ k / (max(d, m)^2)

m

m


Clamping

Contrib. ≈ min( k / d^2, b )

b

b


Clamping – some math

Contribution ≈ k / d^2 P( ray.length ) ≈ ray.length^2 Mathematica happens Variance ≈ sqrt( b ) Bias ≈ 1 / sqrt( b ) MSE = Variance + Bias^2 = sqrt( b ) + 1 / b Optimal convergence:

b = base * iteration ^ 0.66


Results – Manual clamping


Results – lowest RMSE


Results - RMSE

20 200 2000 20000

0.000333333333333333

power = 0


Results - RMSE

20 200 2000 20000

0.000333333333333333

power = 0

power = 0.33

power = 0.66

power = 1


Results - RMSE

20 200 2000 20000

0.000333333333333333

power = 0power = 0.33power = 0.66power = 1power = 2


Results - RMSE

2000 20000

power = 0power = 0.33power = 0.66power = 1power = 2


Conclusion

GPU Lightcuts work Limited by memory

Progressive – averaging images Needs clamping

Can relax clamping – #VPLs ^ 0.66 Works for any VPL method

Look into Multidimensional Lightcuts

Thank you!

Tomáš Davidovič

progressive lightcuts for gpu

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