ZBRUSH SKIN EF­FECTS

3D Artist - - FRONT PAGE -

This im­age, King Of The Streets, is a per­sonal project that was born from a meme that I found that said ‘Sit back. Re­lax’. I de­cided to trans­form it into a full-of-at­ti­tude small crea­ture to send a pos­i­tive mes­sage about the power of at­ti­tude, with a badass frog that might be tiny but rules the for­est!

Ev­ery project starts from some re­search but do not get lost, you have to take de­ci­sions and I tell you this be­cause it usu­ally gets me trapped. Since this species has ap­prox­i­mately 15-30 colour vari­a­tions, I needed to ex­plore a lot, Sub­stance Pain­ter was key for quick test work­flow. After some ex­plor­ing I chose this poi­sonous straw­berry dart frog that kind of looks like Dead­pool. I ac­cen­tu­ated the anatomy and added some cool gang style props to get a more pow­er­ful char­ac­ter. I wanted to make it look like a rock star por­trait so I played with the pose with a very di­rect look to the spec­ta­tor and with dra­matic light­ing.

This tu­to­rial will fo­cus on the cre­ation of the skin of this frog from start to fin­ish. So it will guide you along all pro­cesses: sculpt­ing the de­tails, cre­at­ing all maps and ren­der­ing the fi­nal piece.

This process also ap­plies to any other soft­ware.

01

Break down the ar­eas First of all, it is very im­por­tant to dif­fer­en­ti­ate each area and sim­plify them by break­ing down into sim­pli­fied struc­tures to un­der­stand the com­plex de­tails. On the belly area there are cir­cu­lar form-like cells. For this I used any ir­reg­u­lar cir­cle al­pha with the Stan­dard brush. You can eas­ily make it in Pho­to­shop de­form­ing and blur­ring a cir­cle with the Stan­dard brush. For the cell wrin­kles, con­nect the cir­cu­lar bumps (cells) on the belly fol­low­ing a con­tin­u­ous path with the Dam_­s­tan­dard brush in Zsub mode. Imag­ine a fish­ing net over all these bumps or wa­ter waves around rocks.

02

Add de­tails I like to start defin­ing the wrin­kle by draw­ing with the Dam_­s­tan­dard brush and then to get the vol­ume of the fold formed by the skin, I use the Stan­dard brush with a big­ger stroke.

I sculpted wrin­kles for the lower eye­lid by fol­low­ing the or­bital eye move­ment. Some larger wrin­kles ap­pear be­hind the knee due to the flex­ing of the leg. Make sure these wrin­kles van­ish and smooth out when com­ing to the front side be­cause this is where the skin is most tensed. Fol­low the same process for the arms. In this layer I also added some wrin­kles around the lip and very small wrin­kles ev­ery­where around to add a more skin-like feel­ing.

03

Add im­per­fec­tion The rough skin of the back has a more ir­reg­u­lar sur­face so gen­er­ate a gen­eral noise us­ing the Stan­dard brush with a big draw size set on spray mode and de­fault 07 and 08 al­phas. After, I try to use dif­fer­ent al­phas, big­ger and smaller and then ap­ply a gen­eral Smooth­peaks brush, this gen­er­ates a more skin-like ef­fect. I

do this process twice to get a very ir­reg­u­lar sur­face and after­wards I do a fi­nal pass of very sub­tle de­tails. Add some warts here and there, mostly around the rougher skin. Just use an ir­reg­u­lar cir­cu­lar shape as the al­pha, spar­ingly, around the skin with dif­fer­ent sizes and in­ten­si­ties again with the Stan­dard brush.

04

Work on the back Skin on the back is thicker and suf­fers a lot of com­pres­sion and ex­ten­sion so deeper wrin­kles form like an ac­cor­dion. Re­mem­ber wrin­kles al­ways go in the trans­ver­sal di­rec­tion to the move­ment. Fi­nally, I al­ways add a layer for the asym­me­try.

Na­ture rarely stays sym­met­ri­cal so it would look un­real if we don’t add some nat­u­ral dif­fer­ences and it is a good op­por­tu­nity to ac­cen­tu­ate the ex­pres­sion of our hero char­ac­ter. I found it in­ter­est­ing to raise the smile a bit to get a cooler and more hu­man­ised ges­ture.

05

Bake maps To bake the dis­place­ment map I use Zbrush Multi Map Ex­porter. You need to set your low sub­div level from where you will ap­ply this map later on in the shader. For the res­o­lu­tion I highly rec­om­mend 8192 so you get the max­i­mum res­o­lu­tion. Set mid to 0 and 32-bit EXR. For 3ds Max it is im­por­tant to ac­ti­vate Flipv, oth­er­wise you will get the map up­side down and a headache. For the rest of the maps I use the straight­for­ward tool from Sub­stance Pain­ter’s Tex­ture set set­tings/bake mesh maps, ide­ally set as 8k maps. It is im­por­tant to ex­port the cur­va­ture/cav­ity map. An­other way to get this map is from Zbrush, by mask­ing by cav­ity and fill­ing with black colour. Fi­nally, ex­port the re­sult­ing tex­ture from the Poly­paint fea­ture in Zbrush.

06

Cre­ate diffuse map First of all, I sep­a­rated the belly and feet from the rest with a mask. For the back, just cre­ate a fill layer in red and add an­other layer named dots pat­tern with a gen­er­a­tor, with 3D sim­ple noise with the Po­si­tion map as in­put. Ba­si­cally, you can con­trol the amount of dots with the scale con­trol.

There is al­ways some need to fix so I man­u­ally paint to cor­rect any bad-look­ing ar­eas. Fi­nally, I add a 3D Wor­ley noise on top for an­other layer of ex­tra smaller dots on screen mode set at 25. Tip: you can ac­ti­vate/de­ac­ti­vate the mask layer by press­ing Shift on the mask.

07

Fin­ish work­ing on diffuse map It is very im­por­tant to be clean, so I made two fold­ers: Belly and Back. The belly has a base layer filled in black and an­other layer with the cur­va­ture/cav­ity map used as a mask in nor­mal mode in 10% of in­ten­sity, this en­hances the hard work we did sculpt­ing all the de­tails in Zbrush. I will later use it also to mask Re­flec­tion rough­ness. Fi­nally, I add fin­ish­ing touches in Pho­to­shop, adding a skin layer in soft light mode and paint­ing man­u­ally the ex­tra de­tail on the feet mak­ing them look like rock style gloves.

08

Shade The V-ray al­sur­face ma­te­rial is a great and easy-to-use shader for skin. Al­ways take scale into ac­count when ren­der­ing with SSS shaders. In this case the frog is 18cm high. This is not its real size, but this is okay for help­ing to con­trol the SSS ef­fect. You can al­ways bal­ance the ef­fect with the scale fac­tor. Next, plug in the diffuse map, nor­mal bump and fi­nally add the cur­va­ture map into the rough­ness and sss1 colour tex­ture. Don’t for­get to in­crease the SSS mix, oth­er­wise you won’t get the SSS ef­fect. Tip: for con­trast­ing maps, the curves of the out­put mode in each map are re­ally use­ful. The V-ray dis­place­ment mod­i­fier has a bet­ter con­trol than the dis­place­ment map. De­ac­ti­vate any fil­ter blur on the map that is set as a de­fault op­tion. Plug a Vray­h­dri map with the 32-bit EXR dis­place­ment map you got from Zbrush. The Texmap min should be -1 and 1 but you can play with val­ues a bit.

09

Ren­der I rec­om­mend to start sim­ple, plac­ing lights with no ma­te­ri­als and move pro­gres­sively step by step to dis­place­ment, bumps map, SSS shaders and the more time-con­sum­ing stuff. The re­cent V-ray in­ter­ac­tive ren­der­ing is handy for play­ing with light in­ten­si­ties and po­si­tions. The scene is com­posed of three lights and a HDR light to pro­vide in­ter­est­ing re­flec­tions. The main light is a big top area light. A back area light il­lu­mi­nates the right of the frog with high in­ten­sity, giv­ing a lot of con­trast on the back and high­light­ing the sculpt. A rim area light en­hances the sil­hou­ette and makes our char­ac­ter look more in­ter­est­ing, and pop out of the back­ground.

Fi­nally, I add fin­ish­ing touches in Pho­to­shop, adding a skin layer in soft light mode

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