PIPE­LINE TECH­NIQUES: Dis­cover real-time light­ing techiques

3D Artist - - CONTENTS -

Learn to light a cin­e­matic with Joey Lenz and Phil Liu

in this tu­to­rial, we’ll cover the ba­sics of how to use an in­dus­try-lead­ing game en­gine, like un­real 4, for a cin­e­matic ren­der. We’ll go over per-shot light­ing tech­niques in a real-time en­vi­ron­ment, ma­te­rial set­ups for painterly falloffs and gra­di­ents, and cus­tom ren­der passes for com­posit­ing and lay­er­ing of ef­fects. For this black-and­white study, we were in­spired by Bl­iz­zard’s Di­ablo char­ac­ter, and the un­der-lit mood was de­rived from the orig­i­nal Franken­stein movie for a hor­ror theme. The bust was sculpted by Phil Liu in Zbrush and was later op­ti­mised for un­real 4 im­por­ta­tion. We used a PBR work­flow as a base but it evolved with more artis­tic choices to get the ex­act look and feel we were af­ter.

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Light­ing choices in the world of cgi, it’s a com­mon prac­tice to use global il­lu­mi­na­tion tech­nol­ogy to as­sist with ren­der­ing very re­al­is­tic in­di­rect light­ing. how­ever, it’s not al­ways nec­es­sary for ev­ery case de­pend­ing on the in­tent or how much con­trol is needed over the light­ing. in our case, we were go­ing for a very spe­cific look, and we felt it would be bet­ter for us to man­u­ally de­ter­mine ev­ery as­pect of the light­ing. There­fore, each light in our ue4 project was set to Move­able and no pre­com­puted, dif­fuse in­di­rect light­ing was used. 02 Per-shot light­ing Games use a lot of in-th­er­ound light­ing, where it has to look good re­gard­less of where the player/cam­era is look­ing. Our project re­quired the cam­era to be in a locked po­si­tion. With our ren­der only hav­ing to look good from only one an­gle, we could use per-shot light­ing tech­niques and get away with more. since we didn’t have to worry about light­ing op­ti­mi­sa­tions tra­di­tion­ally found in games, like over­lap­ping dy­namic light count lim­its, we had the free­dom to use as many lights as nec­es­sary. For in­stance, some of our lights were used to just add small ac­cented, local high­lights.

03 Falloff ef­fects some­times you want spe­cific ar­eas to have soft, shaded gra­di­ents. While this can be achieved with lights, it may not al­ways work for ev­ery cir­cum­stance. Dark lights can re-cre­ate this look, which is when a light’s in­ten­sity has a neg­a­tive value.

es­sen­tially, it sucks up pre-ex­ist­ing light, leav­ing that area darker. ue4 does not al­low for this, so we had to use a dif­fer­ent method.

We ended up us­ing planes with pro­ce­du­rally-gen­er­ated gra­di­ent ma­te­ri­als and placed them be­tween the bust and the cam­era for con­trol over the falloffs. A sim­i­lar tech­nique was used for the flick­er­ing glow ef­fects.

04 Ren­der passes cus­tom ren­der passes were cre­ated for more con­trol in the com­posit­ing stage. This was ac­com­plished with the use of ma­te­ri­als tai­lored for spe­cific passes. For ex­am­ple, RGB mask/mat­tes used ma­te­ri­als with their shad­ing model set to un­lit so they would give us flat base colour val­ues with­out light­ing/shad­ing in­for­ma­tion on the ge­om­e­try. An­other pass in­cluded iso­lat­ing the flick­er­ing fire lights emit­ting from the head and to cre­ate a matte out of them. To do this, a white ma­te­rial was as­signed to the ge­om­e­try, and only the fire lights were vis­i­ble in this pass.

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High-res screen­shots We needed high­res­o­lu­tion ren­ders and ue4 of­fers a tool for this. in the view­port, there is a drop-down ar­row in the top, left-hand cor­ner. When you click on it, you’ll see the high Res­o­lu­tion screen­shot tool. A new win­dow then ap­pears with an op­tion called screen­shot size Mul­ti­plier. We set ours to 4 which gave us ren­ders 4x our screen res­o­lu­tion. The idea be­hind this is so you can work with higher-res­o­lu­tion ren­ders that will even­tu­ally be down­sized for the fi­nal out­put. The results tend to be sharper than if you worked at the fi­nal res­o­lu­tion the en­tire time.

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Com­posit­ing There are many pro­grams and ways to com­pos­ite these days. We kept it sim­ple and just used Pho­to­shop. All the ren­der passes were im­ported as lay­ers and stacked ac­cord­ingly. For an­i­mated lay­ers, as well as keyframes, we used the Time­line tool, which can be found un­der Pho­to­shop’s Win­dow menu set. With this, we were able to scrub through the an­i­ma­tion and edit lay­ers un­til we had results we were happy with. Adding FX was one of the fi­nal touches for the project. We ren­dered them out from a pro­gram called Werble and then com­pos­ited them into our Pho­to­shop scene.

Joey Lenz and Phil Liu polyplant.co the-last-pixel.com Bio Joey is a light­ing artist in the videogames in­dus­try. He’s worked on games like Halo 5, Mod­ern War­fare Re­mas­tered, and the Forza se­ries.Phil is an en­vi­ron­ment artist for Mono­lith Pro­duc­tions. He has worked on games like Mid­dle-earth: Shadow or War, Guild Wars 2: Heart of Thorns and Halo 5.

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