STEP BY STEP: Dis­cover the power of Ren­der­man 22

Fol­low along to see how this homage to the walk­ing teapot was cre­ated with the help of Ren­der­man 22

3D Artist - - CONTENTS -

Mas­ter the new Ren­der­man 22

The pur­pose of a prax­inoscope is to cre­ate an op­ti­cal il­lu­sion as it spins, caus­ing a se­ries of static draw­ings to ap­pear to an­i­mate. The Ren­der­man Walk­ing Teapot proved to be a good sub­ject for this par­tic­u­lar ren­di­tion of a prax­inoscope by mak­ing a se­ries of 12 sculpts ap­pear to walk. Cre­ated to func­tion as a real ob­ject, this CGI pro­to­type was built with Au­todesk Maya, Sub­stance Pain­ter and the new re­lease of Ren­der­man 22. This tu­to­rial shows the power found in Ren­der­man’s im­pres­sive new lev­els of in­ter­ac­tiv­ity, so now you can work di­rectly in the ren­derer from mod­el­ling all the way through to fi­nal light­ing. We’ll also look at in­ter­est­ing tech­niques for look de­vel­op­ment, light set-up and how to make so­phis­ti­cated pho­to­re­al­is­tic images fast and ef­fec­tively with Ren­der­man 22.

You can work di­rectly in the ren­derer from mod­el­ling all the way through to fi­nal light­ing

01 Walk this way A good walk cy­cle is an es­sen­tial re­quire­ment. first, cre­ate a 12-frame walk cy­cle (ours was made by ro­to­scop­ing åa video of a real walk­ing teapot in Maya). next, we’ll use that cy­cle to gen­er­ate a se­ries of 12 static teapots, placed around the ori­gin. To val­i­date the cy­cle it’s just a mat­ter of key fram­ing the group of teapots to make a full ro­ta­tion once every sec­ond. It’s sim­ple to play the an­i­ma­tion in Maya and ad­just as needed (with Maya’s frame Rate set to 24fps and Play­back Speed to 24fps x 0.5) un­til we have our walk­ing teapot.

02 Po­si­tion the mir­rors Place­ment of mir­rors is im­por­tant if we want a prop­erly func­tion­ing prax­inoscope. for­tu­nately, the new IPR in Ren­der­man 22 makes that sim­ple, al­low­ing the cre­ation, po­si­tion­ing and edit­ing of ge­om­e­try so we can see ex­actly how the re­flec­tion looks in in­ter­ac­tive time. In fact, we can start up Ren­der­man in the Maya view­port, and then it’s just a mat­ter of cre­at­ing a polyg­o­nal cylin­der with 12 sides (you’ll want to add hard edges), at­tach­ing a Mir­ror shader (you’ll find one in Ren­der­man’s Pre­set Browser) and edit­ing the ge­om­e­try un­til the re­sult is per­fect. fast and easy, just how we like our CGI.

03 It’s not old… it’s vin­tage! for art di­rec­tion, the goal is to cre­ate some­thing that wouldn’t have looked com­pletely out of place in 1876, the year the prax­inoscope was in­vented, mean­ing old-fash­ioned com­po­nents made of worn metal, painted metal and glass. As with the mir­rors, build ev­ery­thing dur­ing an IPR ses­sion to get fi­nal-pixel feed­back on how the mod­els will look. Use the Ren­der­man Pre­set Browser to quickly try out var­i­ous looks on ob­jects. We’ll add a base, roof, rails and planks to the prax­inoscope and a mag­ni­fy­ing glass and floor to the scene.

04 Look de­vel­op­ment with sub­stance To cre­ate the ap­pear­ance of a vin­tage ob­ject we’ll need to make the sur­faces look aged and worn. Sub­stance Pain­ter is a fan­tas­tic tool for cre­at­ing these types of looks us­ing a com­bi­na­tion of pro­ce­du­ral­ism, tex­tures and sur­face topol­ogy. To do this you’ll want to in­stall the Ren­der­man for Sub­stance Pain­ter plugin writ­ten by Philippe leprince, which you can find here: github.com/pleprince/rfsp. This plugin al­lows you to cre­ate shaders in Pain­ter and ex­port them di­rectly to your Ren­der­man Pre­set Browser, mak­ing the process straight-for­ward. how­ever, the shaders usu­ally re­quire some fur­ther tweak­ing for best re­sults.

05 Two lobes are bet­ter than one Ren­der­man ships with the ad­vanced Pixar Sur­face shader. Pixar Sur­face sup­ports mul­ti­ple spec­u­lar lobes, and we’ll use this fea­ture to en­hance some of our shaders we ex­ported from Pain­ter. In our ex­am­ples we have sim­ple sur­faces with dif­fuse, spec­u­lar and bump. now we will add a sec­ond spec­u­lar lobe, Clear Coat and mod­ify its bump in­de­pen­dently to have a value of zero (in the Clear Coat’s Ad­vanced tab). This will make the Clear Coat smooth while the other spec­u­lar lobe with have bump, giv­ing depth to the sur­face. fancy, and it’s eas­i­est to see the re­sults in the images.

06 Easy colour vari­a­tion The real world is full of slight im­per­fec­tions, and adding these vari­a­tions to your CGI scenes can make them more be­liev­able. The down­side of adding vari­a­tion is that it can make scenes more com­plex to cre­ate and man­age. for­tu­nately, we can cre­ate com­plex­ity non-de­struc­tively so you get the best of both worlds… com­plex­ity that’s easy to man­age. In this ex­am­ple we will add colour vari­a­tion to the planks. Sim­ply plug a pxr­vary node into the colour of the shader and be­gin tweak­ing pa­ram­e­ters, and re­mem­ber you can see the up­dates im­me­di­ately in your IPR ses­sion.

To cre­ate a vin­tage ob­ject we’ll need to make the sur­faces look aged and worn. Sub­stance Pain­ter is a fan­tas­tic tool for cre­at­ing these types of looks us­ing a com­bi­na­tion of pro­ce­du­ral­ism, tex­tures and sur­face topol­ogy

07 Dif­fer­ent tex­tures for teapots The paint on each teapot is worn, but we don’t want them all to have the same worn pat­tern. At the same time, it’s eas­ier to man­age with one teapot shader. We can do both. At­tach our shader from Sub­stance Pain­ter to all the teapots – one for the body and one for the lid – and then ran­domly as­sign dif­fer­ent tex­ture sets to each ob­ject by adding the node pxr­mul­ti­tex­ture. The node pxr­mul­ti­tex­ture (con­nected to a pxr­tile­man­i­fold) al­lows up to nine tex­tures to be ran­domly as­signed to dif­fer­ent ob­jects based on name, id or prim­var. now it’s easy to add more tex­ture vari­a­tions, or change them com­pletely.

08 Vary hue with prim­i­tive vari­ables The next goal is to have the teapots tran­si­tion from red to yel­low for a cool ef­fect when an­i­mated. In­stead of at­tach­ing mul­ti­ple shaders, we can do this with the same Pixar Sur­face (one for the body and one for the lid). Add a pxrhsl node (hue, Sat­u­ra­tion and lu­mi­nance) to the teapot’s Dif­fuse Color, and feed the pxr­mul­ti­tex­ture into it. next con­nect a pxr­prim­var node into the value of pxrhsl’s hue. now add a prim­var (prim­i­tive vari­able) to the Shape node of each ob­ject called ‘hue’ and spec­ify an ap­pro­pri­ate hue value, from red to yel­low. now one shader will as­sign a dif­fer­ent hue to each teapot.

09 In­ter­ac­tive light­ing now it’s time to light the scene. If it isn’t al­ready run­ning, start an IPR ses­sion. Be­cause Ren­der­man’s lights and shaders are phys­i­cally based, one use­ful thing to do is to cre­ate a mir­rored sphere, grey sphere and a white sphere in your scene so you can bal­ance the lights and shaders ac­cord­ingly. Re­mem­ber sur­faces ab­sorb en­ergy, so for the white ball set your Color to RGB=0.8, which is the ap­pro­pri­ate set­ting for white acrylic, and set your grey sphere to RGB=0.18. next add an area light and an en­vi­ron­ment light (pick one from the Ren­der­man Pre­set Browser). Tweak un­til the light­ing is blocked in.

Adding vari­a­tion to these ob­jects is de­sir­able for our fi­nal look, but it’s in­ef­fi­cient to add a sep­a­rate shader to each in­di­vid­ual ob­ject

10 IES pro­files for re­al­ism Pre­vi­ously we added sub­tle vari­a­tion to our Pixar Sur­face shaders to make things look more re­al­is­tic. now we’ll add some re­al­ism to our light­ing with IES Pro­files. You can down­load your own IES pro­files from Philips here: usa.light­ing.philips.com. The pro­file will shape the light in a nat­u­ral way, giv­ing the light­ing sub­tle char­ac­ter­is­tics based on the pro­file. In the area light, load an IES Pro­file in the light Pro­file sec­tion.

You will see the re­sult im­me­di­ately in the IPR ses­sion. You’ll find ad­vanced con­trols for IES Pro­files in the Ren­der­man Ad­vanced tab of the Ren­der Set­tings.

11 Cre­ate a light fil­ter The light fil­ters in Ren­der­man are the same used in Pixar pro­duc­tions and al­low light­ing to be cre­atively di­rected with­out hav­ing to ad­just the lights them­selves. It’s another non-de­struc­tive work­flow. There are sev­eral types of fil­ters: Barn Door, Cookie, Gobo, Multi-light, Ramp-light and Rod-light. In this case we’ll add a Rod-light fil­ter to our Area light, so right-click in the light fil­ters field to se­lect a Rod-light. In the other en­vi­ron­ment light, right-click in the light fil­ters field as well. You’ll see and can pick the fil­ter that was just made. now this Rod-light will af­fect both lights.

12 Po­si­tion the fil­ter We’ll take our new Rod-light and move it around in our scene, scal­ing and ad­just­ing un­til it sur­rounds the prax in scope. In the IPR ses­sion you’ll see that ev­ery­thing in­side the Rod-light is black. To cre­ate the ef­fect of a spot­light, tog­gle In­vert so ev­ery­thing out­side of the Rod-light is in shadow. Try mov­ing the Rod-light around and chang­ing dif­fer­ent pa­ram­e­ters to try out dif­fer­ent looks; you’ll be able to see the re­sults im­me­di­ately in the IPR ses­sion. Mul­ti­ple fil­ters can be added to the same light as well. fil­ters of­fer many ways to sculpt light in­tu­itively and non-de­struc­tively.

13 Com­po­si­tion now we have the prax­inoscope in all of its glory, fully shaded and lit. for our fi­nal ren­der­ing we need to com­pose a shot. To make things more in­ter­est­ing, frame the shot through the mag­ni­fy­ing lens. With the IPR ses­sion run­ning, move the cam­era and the mag­ni­fy­ing glass and cre­ate an in­ter­est­ing com­po­si­tion. If the re­frac­tion doesn’t look right, try scal­ing the lens to in­crease or re­duce the amount of dis­tor­tion. With im­me­di­ate feed­back in IPR it’s easy to frame this some­what tricky shot.

14 Pixar Cam­era To fin­ish up our prax­inoscope we’ll add some im­per­fec­tions to our cam­era us­ing a cus­tom pxr­cam­era. Se­lect the Maya Cam­era and en­able Depth of field. Ad­just un­til the Dof is to your lik­ing. next, go to the Ren­der­man tab of the cam­era. once in the Ren­der­man tab we can tog­gle en­able Cam­era Pro­jec­tion and right-click on the new field to se­lect pxr­cam­era. here we can add a vi­gnette to the cam­era, as well as more com­plex ef­fects like Tilt Shift Dof, which we can also view in our IPR ses­sion. The phys­i­cal cam­era con­trols are ca­pa­ble of cre­at­ing some unique looks.

15 Ren­der with the Denoiser fi­nally, be­fore ren­der­ing an an­i­mated se­quence en­able the Denoiser, which al­lows images to be ren­dered with fewer sam­ples for faster ren­ders. The Denoiser runs as a post-process, re­mov­ing any ar­ti­facts. In the new Ren­der­man for Maya, it’s straight­for­ward to denoise spe­cific passes, Aovs and lpes as the Denoiser is now found in the Aovs tab in the Ren­der Set­tings (just se­lect the Beauty Pass). And that’s how we made our prax­inoscope!

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