Tus txheej txheem ntawm txoj kev ua haujlwm yog lub luag haujlwm tseem ceeb hauv lub computer graphics kev voj voog. Peb yuav tsis mus rau ntau qhov tob ntawm no, tab sis tsis muaj kev sib tham ntawm CG pipeline yuav tiav tsis tas yuav piav txog cov cuab yeej thiab cov hau kev rau rendering 3D dluab.
Zoo li Kev Lom Zem
Rendering yog txoj haujlwm tshaj plaws ntawm 3D ntau tshaj plaws, tab sis nws yeej yuav to taub yooj yim heev hauv lub ntsiab lus ntawm ib qho analogy: Npaum li ib tus kws yees duab yuav tsum tsim thiab sau nws cov duab ua ntej lawv tuaj yeem pom tshwm ntsej muag, computer graphics cov tub txawg muaj lub luag haujlwm zoo ib yam yuav tsum muaj.
Thaum ib tus artist ua haujlwm ntawm 3D scene , cov qauv nws ua tau yog ib qho piv txwv ntawm cov ntsiab lus thiab cov chaw (ntau ntxiv, cov hauv paus thiab cov kabmob) hauv qhov chaw uas muaj peb sab.
Lo lus rendering yog hais txog cov lus teb uas siv los ntawm 3D software pob lub cav xa mus rau qhov chaw ntawm ib qho kev ua zauv los mus rau qhov xaus 2D duab. Thaum txoj kev, tag nrho cov scene tus spatial, textural, thiab cov teeb pom kev ua ke yog txiav txim siab qhov xim tus nqi ntawm txhua tus pixel hauv cov duab uas tsis txaus siab.
Ob Hom Kev Rendering
Muaj ob hom kev ua haujlwm loj, lawv cov thawj sib txawv ua qhov ceev thaum twg cov duab raug suav ua tiav thiab xaus.
- Real-Time Rendering: Siv sijhawm tiag tiag yog siv cov kev ua si hauv gaming thiab kev sib tham sib duab, qhov twg cov dluab yuav tsum tau ua los ntawm cov ntaub ntawv 3D ntawm ib qho kev pauv sai heev.
- Interactivity: Vim hais tias nws tsis muaj peev xwm to taub raws nraim li cas ib tug neeg uas ua ntawv yuav nkag mus rau ntawm qhov chaw ua si, cov duab yuav tsum tau muab tso rau hauv "real-time" raws li qhov kev txiav txim nthuav tawm.
- Them Ntaus: Yuav kom txoj kev tawm suab tshwm sim, muaj qis tshaj 18 - 20 nti ib ntus ob zaug yuav tsum tau muab rau lub vijtsam. Txhua yam tsawg tshaj li qhov no thiab qhov kev txiav txim yuav tshwm sim choppy.
- Cov hau kev: Kev ua tiag-sij hawm yog tsim kho los ntawm kev sib tw graphics (GPUs), thiab los ntawm pre-compiling kom ntau li ntau tau. Ib qho zoo ntawm kev ua si ib cheeb tsam cov teeb pom kev zoo yog pre-computed thiab "ci" ncaj qha mus rau hauv ib cheeb tsam kev ntxhib los tsim cov ntaub ntawv txhim kho ceev ceev.
- Offline los yog Pre-Rendering: Kev rho tawm offline siv nyob rau lub sijhawm qhov kev ceev ceev tsawg dua ntawm qhov teeb meem, nrog cov laij zauv feem ntau tau siv cov tub ntxhais siv CPUs ntau dua li cov cuab yeej graphics.
- Predictability: Kev nrhiav offline feem ntau pom muaj nyob hauv cov animation thiab cov teebmeem ua haujlwm uas tsis pom kev nyuaj thiab photorealism tuav kom muaj txheej txheem ntau dua. Txij li thaum tsis muaj kev tsis pom zoo raws li qhov yuav tshwm sim hauv txhua kab, ntau lub tsev kawm ntawv tau paub tias yuav muab faus mus txog 90 xuab moos muab lub sijhawm rau tus neeg thav ntawv.
- Photorealism: Vim hais tias offline rendering tshwm sim nyob rau hauv ib lub sij hawm qhib-thav duab, ntau theem ntawm photorealism yuav ua tau tiav tshaj nrog rendering real-time. Cov cwj pwm, cov cheeb tsam, thiab lawv cov duab sib txuas thiab cov teeb ci feem ntau tau tso cai rau ntau tus polygon suav, thiab 4k (los siab tshaj) cov qauv ntaub ntawv.
Rendering Techniques
Nws muaj peb hom kev ua lej loj siv rau feem ntau txoj kev ua haujlwm. Nyias nyias muaj nyias qhov zoo thiab qhov tsis zoo, ua txhua yam peb siv tau rau hauv qee lub sijhawm.
- Scanline (los yog rasterization): Scanline rendering yog siv thaum kev ceev yog ib qho tseem ceeb, uas ua rau nws xaiv cov txheej txheem rau kev ua ub no thiab cov duab sib tham. Siv cov duab ua duab pixel-by-pixel, ua haujlwm scanline xam rau ntawm lub polygon los ntawm polygon. Scanline cov tswv yim siv los ua ke nrog cov huab cua (preceded) ci tuaj yeem ua kom ncav tau 60 thav ob ntawm ib qho thib ob los yog zoo dua hauv daim npav siab.
- Raytracing: Hauv kev sib tw, rau txhua pixel hauv qhov chaw, ib (los sis ntau tshaj) duab (sib) ntawm lub teeb muaj taug los ntawm lub koob yees duab rau qhov khoom kwv ze 3D. Lub teeb ci tom qab ntawd dhau los ntawm ib pawg "bounces", uas muaj xws li kev xav lossis nrheev nyob ntawm cov ntaub ntawv nyob rau hauv 3D scene. Cov xim ntawm txhua tus pixel yog ua raws li algorithmically raws li txoj sab ci txoj kev sib txuas nrog cov khoom hauv nws txoj kev taug. Raytracing muaj peev xwm ntau dua photorealism dua scanline, tiam sis nws yog qeeb qeeb qeeb qeeb.
- Radiosity: Tsis zoo li cov kab khiav tawm, radiosity yog suav ywj siab rau ntawm lub koob yees duab, thiab yog qhov chaw taw qhia tsis yog pixel-los-pixel. Qhov tseem ceeb tshaj plaws ntawm lub xov tooj cua yog kom muaj ntau yam simulate nto xim los ntawm kev siv nyiaj rau cov duab tsis ncaj (kab tawm hauv lub teeb). Radiosity feem ntau yog cov duab ntxoov ntxoo thiab xim daj, uas yog lub teeb ci ntsa iab "bleeds" rau ntawm cov chaw nyob ze.
- Hauv kev xyaum, xov tooj cua thiab kab lig kev cai feem ntau siv tau ua ke nrog ib leeg, siv qhov zoo ntawm txhua qhov kev lag luam kom ua tau ntau theem ntawm photorealism.
Rendering Software
Txawm hais tias kev ua hauj lwm los ntawm kev ua haujlwm zoo dua, hnub no tus software muab kev yooj yim to taub tsis yog qhov uas ua rau ib tug kws kos duab yeej tsis xav nrog kev ua lej. Render cav yog muaj nrog txhua qhov 3D software suite, thiab feem ntau ntawm lawv muaj cov khoom thiab teeb pom kev zoo tej pob khoom ua rau nws ua tau kom muaj kev sib txuam theem ntawm photorealism.
Qhov ob feem xyuam tawm cav:
- Mental Ray - Packaged nrog Autodesk Maya. Mental Ray yog incredibly ntau yam, kuj yoojyim, thiab tej zaum cov tswv yim tshaj plaws rau cov ua cim uas xav tau kev qis qis. Kev tawm tsam txoj hauv kev siv yog kev sib txeeb thiab "thoob ntiaj teb illumination" (radiosity).
- V-Ray - Koj feem ntau pom V-Ray siv tau nrog 3DS Max-ua ke lub khub yog ua tsis ncaj rau architectural visualization thiab ib cheeb tsam rendering. Tus thawj coj ntawm VRay hla nws cov neeg sib tw yog nws cov cuab yeej siv teeb pom kev zoo thiab cov ntaub ntawv uas nws kim heev rau arch-visiz.
Rendering yog ib txoj kev kawm, tab sis tuaj yeem nthuav heev thaum koj yeej pib ua ntxaum saib ntawm qee hom kev kawm.