Membuat Cahaya Lilin MEnggunakan Lightworks Render

7/16/2019 Membuat Cahaya Lilin MEnggunakan Lightworks Render

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LightWorks in ArchiCAD142

Candlelight and Crystal

Tis exercise studies light, reraction and modeling at the macro level in ArchiCAD—about as small as it can get and way

more detail than you could ever use. Based on a typical “tea light,” a squat candle nestled in a heavy glass base, this exercise builds a plausible ame model, lights the scene with plausible candlelight and addresses theimportance o how the heavy reractive glassbase interacts with light energy.

Te Situation

Te delight o the tea light is basking in thebedazzling reraction o the weighty base as it

cradles the candle and how this radiance glowsin a modest space. Our challenge is to model this

light behavior without benet o the reractivereocusing o the candles by the glass (the brightrings surrounding each real light in the adjacentphotograph). Study the related material settingsto uncover the details o solving this situation.

Te Base

Te base was swept with Profler, ollowing

the actual tea light prole (no guessing).Accurate measurements showed it was NO aton top, but sloped slightly down and outward.Te only problem with Profler is that a rotatedprole has a matching start and end aceseen in a transparent object as a visible planetraveling through the glass. ake care to hidethis seam away rom the camera by placing itdirectly behind the ame in line with the camera

viewpoint—sneaky.

Cast glass or lead crystal has a highreractive index, a highly polished suraceand contains irregularities caused by thermal

(Let)

A rendering o three tea candles

on a granite countertop, ater some Photoshop work to blur

the background and diuse thecandle glow.

Big deal—but takes all day to

render these precious ourteen-hundred pixels because o cast

glass reraction calculations.

(Right)

An actual digital photograph o three tea lights on my bathroom

countertop clearly shows theradiant glare rom a cheap lens

and the reracted ring o light en-circling the tea lights rom each

candle shining through the thick glass bases.

We can’t directly do that with a

LightWorks eect; we must add a specic light source to do it.

Cast Glass ea Light

Base: Te high rerac-

tion clear material is given subtle sophistication

with a large transpar-ent texture map or some

enigmatic distortion likeinduced by shrinking dur-

ing cooling ater casting.

(Let) Glass Reracted texture map.



Chapter Four: Tricks 143

curing. Te base model lacks imperections androughness that enhance material reraction. Tis

variation uses a subtle texture map to disruptthe even passage o light through the object,simulating irregularities in the casting.

Te Flame Model

Te intense, opaque core ame and itssurrounding translucent plasma halo werecreated in two parts with Profler sweeps. Te

ame assembly doesn’t actually glow, but reectslight energy (with the addition o some emissionshader) rom the light sources in such closeproximity to it.

Readers skilled in GDL should reduce Profler RESOL to 5 rom the deault 32 to speedimaging o these two shapes, which will beobscured later. RESOL controls the number o acets a swept object has through the swept path.

For this exercise, I elected to representa ame rom an overly long wick having anexcessive plasma tail. Candle users oten trimwicks to reduce ame size at this point in the

burn cycle. You might choose otherwise.Relative to the tea candle photo where the

wicks were new and the ames small, the modelames are absurd. In proling the ames using all, even the nest magic wand setting produceda crude geometry that did not ollow the tiny

shape.Te Wick

I skipped modeling the wick, but GDL enthusiastsmay wish to make an ON/OFF option or their tea lights,in which case you’d also want to make a black and awhite wick or “new” and “used.” Perhaps consider alsomaking the wax shrink parametrically as the candle waxis consumed by the ame…just a thought.

Te Candle

Nothing but wax. Emulating the

translucent reection o wax requires a smallamount o plain coverage transparency shaderin addition to the translucent reection shader.Qualities o transparency and translucency areclosely related and in some cases a patternedtexture map as a transparency mask can helpbridge between reraction, transparency andtranslucency. In LightWorks, translucency ismerely a specialized specular reection shader.

Te Light Sources

wo light sources create the essential, i not complete, light eect required.

Te basic light source is the supremely

versatile Wall Light Indirect, the only one o ArchiCAD’s lights than can actually be seen as aphysical light source. It shines straight upwardrom the top surace o the candle wax.

Te supplemental light source is themerely versatile Light Cone Down shining

directly downward rom a strategic positionhovering above the ame at a height sufcientto cast light over the edge o the base, creatinga ring o light emulating the reracted ringin the photo. Reerring to the study in thelighting chapter, the best shadow edge/angleallo denition was ound with an outer lightcone set somewhere between ninety and onehundred and twenty degrees. Without too muchorethought, I chose ninety degrees, placing thelight just over two inches above the top o the

base. Te adjacent illustration shows the lightcone array over the glass base.

Te Photoshopricks

Comparing the rendering to the photo,it is obvious that the rendering is so muchsharper than a noisy, high ISO digital imagemade with a lousy camera lens. Te lousy lens,however, brings a romantic radiant glow to theoverexposed candle ames. o emulate the ame

glow required a tiny amount o Diuse Glow

(Let)

Spline to ll to proled candlefame

components.Outer is translucent

and glowing inner isopaque and glowing.

(Right)

Tree tea lights and

bases show light con- guration or light and shadow casting.



LightWorks in ArchiCAD144

(Above) Te Candle Light Array: Positioned or rhythmic

light circle overlap. Uplighting creates the general radiant light and counter refections, down lighting establishes the

bright circle surround.(Below) Te DownLight: Light Cone Down. Note the high

allo designed to emulate candle light and short light

stopping distance to prevent energy contribution to theoverall scene.

(Above) Te UpLight: Wall Light Indirect creates the gen-eral radiant light and counter refections. Extreme allo

and abrupt light stop.(Below) Te Candle Wax Material: ranslucent reec-tion combines with slight transparency or a waxy appear-

ance.

(Above) Te Candle fame Core: Designed to be a solid

glowing undened orm—will be shrouded by transparent plasma described below.

(Below) Te Candle Flame Plasma: Of-gassing vapor isnot as hot as the core, hence a darker color or the surround-ing mantle.

Emission Attentuation = 0 results in lack o modeling, just like a glowing object should.



Chapter Four: Tricks 145

lter applied in Photoshop. Diuse glow reersto the background color as set in Photoshop—itshould be set to white. Not at all obvious—it’s atrick!

A second trick is graduated blurringapplied rom the upper right hand side o theimage where the door leads to the bedroom.My illustration strategy acknowledges distant

context: vital to convincing the viewer he isoperating in a real environment, not just a stageset.

Te third trick is to induce some grain(noise) into the image, blending the low-lightscene like high speed camera photo sensorswould.

Te Render ime

Te main rendering with three candlestook my 2 x 2.0 G5 ten hours to render these

ourteen hundred pixels at top quality. [“Holy CPU

cycles, Batman!”] Tis is another example o how high reraction with only a ew light sources canexponentially increase rendering time rom whatshould have been just a ew minutes.

Further allout rom having ridiculously high standards, the glass base is also over-resolved, sixty-our segments instead o eighteen(which might have been enough) and too many polygons and high reraction combine into a

time sponge.Errors like this can ruin a job, especially i it is an animation and the excess reractionand over-polygonated[!] suraces are repeated inmany rames. Here, have another cookie whilewe wait.

General Illustration Notes

Study the countertop, particularly theoreground reection. Intended to emulate aplastic laminate nish using a granite pattern

photographed rom stone. Using the adjacentmaterial settings, the diuse, dappled surace

also conveys a sense o rough shadow cast romthe outer lip o the glass bases… a very satisying

visual eect.

Article Conclusion

Satisying illustrations rely on closeattention to remembered impression rather thanliteral detail accuracy. Oten, an object or scenehas subtle qualities, which can be caricatured,in the model or with a light eect, satisying theeye without providing the complete, excruciatingtruth. Only careul study o an object’s lightbehavior can reveal its imaging secret, and a hint

as to what could be let out.Here, lacking radiosity, the typical solution

or intensely lit scenes, we rely on diuse glow and distorted cast glass eects to carry the day.

Counter op Material:

In building a scene with

candlelight, the precisereectivity o adjacent

suraces provide theatrical support or the romance o

the light—minimal mirror with .06 roughness achieves

the ideal satin look.

(Let) Granite texture map rom a photo.

Ater “Beore”: Photoshop tricks—graduated blur con-

rms subject, diuse glow makes it pretty and adding 2%noise completes the dark, romantic eect.

Beore “Ater”: Rendering is too sharp—the eye is led

away rom the scene to the background context elementsincluded in the composition to support scene plausibility.

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Membuat Cahaya Lilin MEnggunakan Lightworks Render