lighting simulations: a parametric perspective...lighting simulations: a parametric perspective...

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Lighting Simulations: A Parametric Perspective

Sarith Subramaniam

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Thinking parametrically

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How many reflections are required to simulate venetian blinds?

Should I use venetian blinds?

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Which luminaire should be used?

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I got interested in Parametric Design in late 2014……

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…and got introduced to Grasshopper and Honeybee

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(Rhino (Grasshopper (Honeybee )))

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Daylighting simulation in Rhino with Honeybee through Radiance

Simulation Results

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Daylighting simulation in Rhino with Honeybee through Radiance

Input

Output

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Daylighting can be analyzed and visualized in different ways

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There is more to Honeybee than Daylighting

Energy

Computational Fluid Dynamics

Photovoltaics

Thermal Comfort

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food4rhino.com/grasshopper-addons/most-downloaded

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Hacking

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github.com/mostaphaRoudsari/Honeybee/graphs/contributors

is an Open Source Software

Mostapha Sadeghipour Roudsari(UPenn, Thornton Tomasetti)

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github.com/mostaphaRoudsari/Honeybee/blob/master/License_Honeybee_GPL.txt

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What is the total radiation when the HVAC system is cooling? Or heating?

What is the total radiation on weekdays only? etc …

Solar radiation on a façade between two time intervals

1 Jan to 31 Dec

3 Apr to 19 Nov …etc.

2 Jan, 3 Mar, 6 Nov …etc.

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Solar radiation between two time intervals for specific hours

Additions and Deletions to the source-code (excerpt)

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The hacked component extended the functionality of the original

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Some of the hacked components

Calculates Annual Sunlight Exposure

Automates Glazing Placement

Filters Weather Data and creates sky definitions

Locates Results

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14th International Radiance Workshop, Philadelphia – August 2015

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We weren’t the only ones interested in Honeybee….

(GSD 6480)*

(A4792) *(ARCH 754) *

(ARCH 407-507) *

*(Refers to the course being taught this academic year that incorporates Honeybee in the syllabus).

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….and I wasn’t the only one trying to hack it.

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….and I wasn’t the only one trying to hack it.

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One of the issues with hacking a “live” software: keeping up!

Hacked Component

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Hacking Developing

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github.com/mostaphaRoudsari/Honeybee/graphs/contributors

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Some hacked components got integrated into the source-code

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Wrote source-code for incorporating luminaires

https://github.com/mostaphaRoudsari/Honeybee/pull/445

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facebook.com/Rhinoceros4point0/posts/10154466953877598

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Limitations……..

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Hacking Developing Rewriting

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github.com/ladybug-analysis-tools/honeybee/graphs/contributors

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Support Revit, Rhino (and everything else)

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The beta-version already works on Revit and Rhino

youtube.com/watch?v=61GdhCy3RMA

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Cross OS Compatibility

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*

The beta-version works on Windows and Unix-based systems…..

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……. but Revit and Rhino are only Windows-based*. So why bother?

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oconv -w materials.rad LfWl.rad

rpict -t 0 -e logfiles/LfWl.log -S 1 -PP pfVOKkZD -x 5532 -y 2718 -dp 4096 -ar 5 -ms 11 -ds .1 -dj

.9 -dt .05 -dc .75 -dr 3 -ss 16 -st .01 -ab 6 -af ambfiles/LfWl.amb -aa .075 -av 2 2 2 -lr 12 -lw

1e-5 -ps 1 -pt .04 -as 5000 -ad 50000 -av 2.5 2.5 2.5

1 core on an 8 core i7 processor (Parallel Processing)

19 hrs, 37 min

Illuminance Luminance

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1e-5 -ps 1 -pt .04 -as 5000 -ad 50000 -av 2.5 2.5 2.5

8 cores on an 8 core i7 processor

19 hrs, 37 min

3 hrs, 14 min

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1e-5 -ps 1 -pt .04 -as 5000 -ad 50000 -av 2.5 2.5 2.5

40 cores on a non-dedicated 288 core Xeon cluster

19 hrs, 37 min

3 hrs, 14 min

1 hr, 18 min

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aws.amazon.com/ec2/

19 hrs, 37 min

3 hrs, 14 min

1 hr, 18 min

19 hrs or a few minutes(user’s choice)

“commission one, hundreds or even thousands of server instances simultaneously”

“…complete control of your instances. You haveroot access to each one…”

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Cross OS Compatibility

Optimize lighting simulation methods

Simplify syntax with abstractions

Type and Error Checking

Apply Object Oriented Programming (OOP)

Implement Recipes

Leverage Python to Reduce Effort

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Ambient Caching

(Ward, Rubinstein, Clear 1988)A ray tracing solution for diffuse interreflection

(Ward 1994)The RADIANCE lighting simulation and rendering system

(Ward 2007)Implementation of irradiance caching in RADIANCE

(Grynberg 1989)Validation of Radiance

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This “scene” has direct and diffused light.

1844 x 966 pixels

1 Pixel: Red Channel, Green Channel, Blue Channel, Luminance

The model inside Rhino

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Reflections for diffused(ambient) sampling: 0

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Reflections for diffused(ambient) sampling: 0, 1

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Reflections for diffused(ambient) sampling: 0, 1, 2

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Reflections for diffused(ambient) sampling: 0, 1, 2, 3

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Reflections for diffused(ambient) sampling: 0, 1, 2, 3, 4

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Reflections for diffused(ambient) sampling: 0, 1, 2, 3, 4, 5

Convergence(almost)

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Strategy: Store and reuse ambient calculations to reduce computation

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Photon Caching





(Jensen 2000)Global illumination using photon maps

(Schregle 2007)Daylight simulation with photon maps

(Schregle, Wienold 2004)Physical validation of global illumination methods: measurement and analysis

Caustics

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Same image with higher exposure

Ambient Photons Caustic Photons

Caustics

Photon distribution depends on diffused light and caustics

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Ambient Photons Caustic Photons

Caustics

Photon distribution depends on diffused light and caustics

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Strategy: Pre-calculate photons and use them for multiple simulations

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Daylight Coefficients





(Tregenza 1983)Daylight coefficients

(Reinhart, Herkel 2000)The simulation of annual daylight illuminance distributions – a state-of the-art comparison of six RADIANCE-based methods

(Reinhart, Walkenhorst 2004)Validation of dynamic RADIANCE-based daylight simulations for a test office with external blinds

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Assumption1: Daylighted spaces are surrounded by a discretized hemispherical sky

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Assumption2: Building geometry and surfaces do not change with time. Sky brightness changes.

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Assumption2: Building geometry and surfaces do not change with time. Sky brightness changes.

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Strategy: Save the geometric relationship between sky patches and the daylighted space in a file.

DC x Sky at 8 AM

DC

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DC x Sky at 9 AM

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DC x Sky at 10 AM

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DC x Sky at 11 AM

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DC x Sky at 12 PM

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DC x Sky at 1 PM

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DC x Sky at 2 PM

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DC x Sky at 3 PM

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DC x Sky at 4 PM

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DC x Sky at 5 PM

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Matrix based methods





(Tregenza 1983)Daylight coefficients

(Ward, Mistrick, Lee, McNeil, Jonsson 2011)Simulating the daylight performance of complex fenestration systems using bidirectional scattering distribution functions within Radiance

(McNeil, Lee 2013)A validation of the Radiance three-phase simulation method for modelling annual daylight performance of optically complex fenestration systems.

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The path between the space and the sky is split into multiple phases or files.

Entire calculation is repeated each time. Calculation time can be reduced by reusing phases

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The split is accomplished by hemispherical sampling.

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The challenge in implementation

oconv –f materials.rad room.rad > room.oct

rfluxmtx –v –o matrices/%s.vmx –I+ -ab 2 –ad 50000 –lw 2e-5 –n 4 –y 100 – objects/glazing.rad –iroom.oct <points.txt

rfluxmtx –v –ff -ab 4 –ad 10000 –lw 1e-5 –c 5000 –n 4 objects/Glazing.rad skyglow.rad –i room.oct > matrices/Glazing.dmx

epw2wea skies/USA_NY_New.York.City-Central.Park.94728_TMY_3.epw skies/NYC.weagendaymtx –m 4 skies/NYC.wea > skies/NYC.smx

dctimestep –h matrices/Glazing.vmx tmatrix/Clear.xml matrices/Glazing.dmx skies/NYC.smx> illuminance_annual.txt

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We started implementing matrix based methods in Honeybee a few months ago.

Dissertation research

Reviewing simulation methods

Software development

Test hypotheses

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Future work: Investigate relevance through hypotheses driven studies

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Thank you

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lighting simulations: a parametric perspective...lighting simulations: a parametric perspective...

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