Pathtracing, Monte Carlo sampling, photon mapping, distance fields. Talk about how pathtracing is implemented and how it solves the main problem of the computer graphics - generating lifelike digital imagery.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
The document discusses various technologies used to create publications. Microsoft Publisher was used to create an early school magazine cover as it was simpler than Photoshop. Adobe Fireworks allowed editing of images by removing backgrounds and cutting out parts for the school magazine. Adobe Photoshop was used for the final music magazine project as it was the most professional program and helped improve skills by recreating an existing magazine. Photoshop tools like the magic wand, eraser, and burn tools were learned. Fonts were found on Dafont.com to make text stand out. A praktica dc 440 camera took photos, a 4GB SanDisk stick saved and transferred work, and Dell and RM laptops were used.
O sonho descreve uma sala cheia de arquivos contendo cada ação e pensamento da vida do sonhador. Ao ver o pequeno arquivo de pessoas com quem falou de Cristo, ele chora de vergonha. Jesus entra e assina Seu nome em todos os cartões, cobrindo as falhas do sonhador com Seu sangue. Jesus o leva para fora, mostrando Seu perdão incondicional.
Tara Fiddler has over 15 years of experience in construction project management, general management, and sales. She is currently a Project Manager at Oelke Construction Company where she manages multiple construction projects from $100k to $2M simultaneously. Previously, she held general manager and assistant project manager roles at Melody Point Builders overseeing all aspects of custom home construction projects from $500k to $2M. She also has experience in sales, recruiting, and benefits coordination. Tara has a Bachelor's degree in Communication from Emporia State University.
The document summarizes feedback received from an audience survey about a music video. Key points:
- The survey asked about likes/dislikes of the video, costume, locations, narrative, and whether an extra location was needed.
- Most respondents felt the locations of a park and stage effectively conveyed the theme of loneliness. However, some disliked background elements in the park footage.
- The costume was seen as fitting for the indie genre. One respondent would have preferred a suit.
- There was consensus that a small narrative about the artist's depression was portrayed, but the ending lacked clarity.
- The majority felt only featuring one artist best represented the theme of loneliness in the song
Victor Hernandez has over 28 years of experience as a general contractor, including founding his own construction company in 2003. He has extensive experience in home construction, remodeling, and repairs. Hernandez is bilingual in English and Spanish, computer literate, and highly skilled in areas ranging from concrete work to roofing. He is known for his conscientious work, trustworthiness, and excellent customer service skills.
Alexander Glova provides his contact information and includes a profile highlighting his excellent communication and leadership skills as well as experience operating heavy equipment. His resume summarizes his achievements including deployments to Qatar and Japan where he maintained inspection standards, as well as medals received. Glova's employment history includes roles in construction, tower technician work, and as a heavy equipment operator supervisor in the Army National Guard. He is currently pursuing additional safety certifications.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
The document discusses various technologies used to create publications. Microsoft Publisher was used to create an early school magazine cover as it was simpler than Photoshop. Adobe Fireworks allowed editing of images by removing backgrounds and cutting out parts for the school magazine. Adobe Photoshop was used for the final music magazine project as it was the most professional program and helped improve skills by recreating an existing magazine. Photoshop tools like the magic wand, eraser, and burn tools were learned. Fonts were found on Dafont.com to make text stand out. A praktica dc 440 camera took photos, a 4GB SanDisk stick saved and transferred work, and Dell and RM laptops were used.
O sonho descreve uma sala cheia de arquivos contendo cada ação e pensamento da vida do sonhador. Ao ver o pequeno arquivo de pessoas com quem falou de Cristo, ele chora de vergonha. Jesus entra e assina Seu nome em todos os cartões, cobrindo as falhas do sonhador com Seu sangue. Jesus o leva para fora, mostrando Seu perdão incondicional.
Tara Fiddler has over 15 years of experience in construction project management, general management, and sales. She is currently a Project Manager at Oelke Construction Company where she manages multiple construction projects from $100k to $2M simultaneously. Previously, she held general manager and assistant project manager roles at Melody Point Builders overseeing all aspects of custom home construction projects from $500k to $2M. She also has experience in sales, recruiting, and benefits coordination. Tara has a Bachelor's degree in Communication from Emporia State University.
The document summarizes feedback received from an audience survey about a music video. Key points:
- The survey asked about likes/dislikes of the video, costume, locations, narrative, and whether an extra location was needed.
- Most respondents felt the locations of a park and stage effectively conveyed the theme of loneliness. However, some disliked background elements in the park footage.
- The costume was seen as fitting for the indie genre. One respondent would have preferred a suit.
- There was consensus that a small narrative about the artist's depression was portrayed, but the ending lacked clarity.
- The majority felt only featuring one artist best represented the theme of loneliness in the song
Victor Hernandez has over 28 years of experience as a general contractor, including founding his own construction company in 2003. He has extensive experience in home construction, remodeling, and repairs. Hernandez is bilingual in English and Spanish, computer literate, and highly skilled in areas ranging from concrete work to roofing. He is known for his conscientious work, trustworthiness, and excellent customer service skills.
Alexander Glova provides his contact information and includes a profile highlighting his excellent communication and leadership skills as well as experience operating heavy equipment. His resume summarizes his achievements including deployments to Qatar and Japan where he maintained inspection standards, as well as medals received. Glova's employment history includes roles in construction, tower technician work, and as a heavy equipment operator supervisor in the Army National Guard. He is currently pursuing additional safety certifications.
William G McBride has over 15 years of experience in construction supervision, equipment operation, and carpentry. He has led teams of up to 60 laborers on projects around the world for companies like Whitewater West Industries and Best Constructors Co. McBride has extensive safety certifications and experience operating heavy machinery including excavators, backhoes, forklifts, and aerial lifts. He is skilled in areas like steel structure erection, electrical and plumbing installation, and following punch lists to complete attractions and buildings according to specifications.
O manual apresenta as diretrizes para uso da identidade visual da Passeduc - Turismo Pedagógico, incluindo versões do logotipo, espaçamento, aplicações corretas e incorretas, e orientações finais sobre fidelidade à marca.
La Unión Europea ha acordado un paquete de sanciones contra Rusia por su invasión de Ucrania. Las sanciones incluyen restricciones a las importaciones de productos rusos de alta tecnología y a las exportaciones de bienes de lujo a Rusia. Además, se congelarán los activos de varios oligarcas rusos y se prohibirá el acceso de los bancos rusos a los mercados financieros de la UE.
The main slideshow for the Economic and Social Council: Humanitarian Affairs Segment. The HAS provides a unique opportunity for Member States to address challenges, operational and normative progress on the humanitarian policy agenda. This year’s HAS took place on 17–19 June in Geneva and focussed on "the future of humanitarian affairs: towards greater inclusiveness, coordination, interoperability and effectiveness".
Ciro Alegría Bazán fue un escritor peruano nacido en 1909 en la provincia de Sánchez Carrión. Estudió en Cajamarca y Trujillo, donde fue alumno de César Vallejo. Se destacó como defensor de los indígenas y clases explotadas. Escribió obras representativas de la literatura indigenista americana, falleciendo en 1967 en Lima.
Este documento proporciona información sobre un cuento de Ciro Alegría titulado "Calixto Garmendia". Resume los elementos intrínsecos del cuento, incluyendo el tema principal sobre el despojo de tierras que sufre el personaje Calixto Garmendia, la idea principal sobre el abuso de la burocracia autoritaria contra los pobres, y los personajes principales como Calixto y su hijo Remigio, así como los personajes secundarios como el alcalde y el juez. También resume brevemente la trama del cuento.
Este documento presenta varios poemas cortos que parafraséan la estructura de un poema épico sobre el Cid Campeador. Cada poema de 3 líneas o menos celebra a un equipo deportivo, artista u otra figura pública siguiendo la forma del poema original, nombrando personajes y detalles clave de forma concisa.
Los textos presentan variaciones de un mismo tema: lo que realmente se regala cuando se da un regalo a alguien. En cada caso, se argumenta que no solo se da el objeto en sí, sino también una responsabilidad, una obsesión y miedos asociados a cuidar y mantener ese objeto. Se resalta que el verdadero regalado es la persona a quien se le da el obsequio, ya que este trae consigo nuevas preocupaciones y obligaciones más allá del objeto en sí mismo.
Spain is a democratic parliamentary monarchy that holds free elections with many political parties and respects equality, freedom of speech, and the rule of law. It is composed of 17 autonomous communities and two autonomous cities, and has a congress, senate, and independent judicial system.
William G McBride has over 15 years of experience in construction supervision, equipment operation, and carpentry. He has led teams of up to 60 laborers on projects around the world for companies like Whitewater West Industries and Best Constructors Co. McBride has extensive safety certifications and experience operating heavy machinery including excavators, backhoes, forklifts, and aerial lifts. He is skilled in areas like steel structure erection, electrical and plumbing installation, and following punch lists to complete attractions and buildings according to specifications.
O manual apresenta as diretrizes para uso da identidade visual da Passeduc - Turismo Pedagógico, incluindo versões do logotipo, espaçamento, aplicações corretas e incorretas, e orientações finais sobre fidelidade à marca.
La Unión Europea ha acordado un paquete de sanciones contra Rusia por su invasión de Ucrania. Las sanciones incluyen restricciones a las importaciones de productos rusos de alta tecnología y a las exportaciones de bienes de lujo a Rusia. Además, se congelarán los activos de varios oligarcas rusos y se prohibirá el acceso de los bancos rusos a los mercados financieros de la UE.
The main slideshow for the Economic and Social Council: Humanitarian Affairs Segment. The HAS provides a unique opportunity for Member States to address challenges, operational and normative progress on the humanitarian policy agenda. This year’s HAS took place on 17–19 June in Geneva and focussed on "the future of humanitarian affairs: towards greater inclusiveness, coordination, interoperability and effectiveness".
Ciro Alegría Bazán fue un escritor peruano nacido en 1909 en la provincia de Sánchez Carrión. Estudió en Cajamarca y Trujillo, donde fue alumno de César Vallejo. Se destacó como defensor de los indígenas y clases explotadas. Escribió obras representativas de la literatura indigenista americana, falleciendo en 1967 en Lima.
Este documento proporciona información sobre un cuento de Ciro Alegría titulado "Calixto Garmendia". Resume los elementos intrínsecos del cuento, incluyendo el tema principal sobre el despojo de tierras que sufre el personaje Calixto Garmendia, la idea principal sobre el abuso de la burocracia autoritaria contra los pobres, y los personajes principales como Calixto y su hijo Remigio, así como los personajes secundarios como el alcalde y el juez. También resume brevemente la trama del cuento.
Este documento presenta varios poemas cortos que parafraséan la estructura de un poema épico sobre el Cid Campeador. Cada poema de 3 líneas o menos celebra a un equipo deportivo, artista u otra figura pública siguiendo la forma del poema original, nombrando personajes y detalles clave de forma concisa.
Los textos presentan variaciones de un mismo tema: lo que realmente se regala cuando se da un regalo a alguien. En cada caso, se argumenta que no solo se da el objeto en sí, sino también una responsabilidad, una obsesión y miedos asociados a cuidar y mantener ese objeto. Se resalta que el verdadero regalado es la persona a quien se le da el obsequio, ya que este trae consigo nuevas preocupaciones y obligaciones más allá del objeto en sí mismo.
Spain is a democratic parliamentary monarchy that holds free elections with many political parties and respects equality, freedom of speech, and the rule of law. It is composed of 17 autonomous communities and two autonomous cities, and has a congress, senate, and independent judicial system.
2. ŠTA JE SVETLO?
• Elektromagnetna radijacija
• 380nm – 760nm (ultravioletna - infracrvena)
• Oko ima receptore koji reaguju na ove talasne duzine
• U mozgu dolazi do percepcije svetla i boja
• Dualna priroda svetla -> fotoni
• Foton – nosilac energije EM radijacije
• Svetlo nastaje dovodjenjem energije na atom, kada stanje postane nestabilno, emituje energiju i tako se
vraća u stabilnije stanje (stanje manje energije)
• Emitovana energija je u obliku fotona
• Primer: lampe, usijan (topljen) metal
3. PATH TRACING
• Jedan tip algoritama za renderovanje
• Path tracing != ray tracing (nije skroz isto, RT je subset PT)
• Tipično se koristi jedan od dva algoritma: rasterizacija ili path tracing
• Može i neki hibridni metod, koji na neki način kombinuje ova dva (REYES)
• Rasterizacija: za date objekte proceniti osvetljenje na njihovoj površini u zavisnosti od postavljenih svetala
• Ideja PT algoritma je dosta stara i bazična:
• Pratiti put fotona (svetla) kako se kreće kroz scenu i kako interaguje sa materijalima
4. foreach light in scene
{
foreach photon emitted from light
{
while not eyeHit( photon )
{
trace( photon, scene )
}
}
}
• Forward ray trace
• Kreni od svetla, stani kad foton stigne do oka
• Problem sa malim brojem uspešno ispraćenih fotona, malo
fotona stigne do kamere/oka, potreban je drugi pristup
• Backward tracing
• Kreni od oka, stani kada foton stigne do svetla
• Većina raytracing renderera koristi backwards metod (mada
ima I hibridnih rešenja, koja su zapravo najčešća)
5. RASTERIZATION RAY TRACING
foreach object in scene
{
foreach pixel on object
{
shade(pixel, object);
}
}
foreach pixel on screen
{
foreach object in scene
{
shade(pixel, object);
}
}
shade(pixel, object)
{
// get material properties of object (color, roughness, reflection ratio etc.)
material = object.material;
// get shading information @ pixel (surface normal, distance from lights etc.)
geometry = calc(pixel, object);
return shade(material, geometry);
}
6. • Odakle krenuti?
• Virtuelna kamera
• Ekran
• 2D polje piksela
• Scena (sfera)
• Konstruisati zrake iz kamere kroz centre piksela
• Pratiti zrak dok ne stigne do svetla
• Proračunati boju
• Proračunati novi pravac
• Apsorbovanje
• Refleksija
• Refrakcija
• Akumulirati rezultate
7. • Imamo zrak (putanju fotona), ali kako znamo gde i sa čime se foton sudara?
• Problem nalaženja preseka linije i proizvoljnog oblika objekta iz scene
• Matematički opisati inicijalnu putanju fotona i objekte u sceni
• Putanja -> vektor pravca + tačka iz koje je potekao
• Objekat -> razložiti ga na neke primitivne elemente (sfere, kvadri, trouglovi...)
• Najčešće se koriste trouglovi
• Nalaženje preseka odredjene primitive u prostoru i datog vektora se može lako računati
8.
9. WHITTED RAYTRACER
• Turner Whitted (1979) predložio nove ideje
• Kada zrak udari površ, može da stvori tri zraka:
refleksije, refrakcije, zrak senke
• Tri tipa površi: difuzne (mat), spekularne
(reflektujuće) i refraktivne (dielektrici)
• Mane:
• aliasing
• hard shadows
• nema GI
• malo tipova materijala
10. Šta želimo:
• GI (color bleed)
• glossy surfaces
• caustics (indirect caustics)
• soft shadows (“AO”)
• AA
• lens effects (DOF, bokeh)
• motion blur
11. RENDERING EQUATION [KAJIYA 1986]
Svetlo iz tačke na površi u odredjenom smeru u zavisnosti od
emitujućeg svetla i
upadnog svetla akumuliranog preko cele hemisfere nad tačkom
Lo – light out
Le – light emitted
fr – BRDF
Li – light incoming
12. BRDF
• Bidirectional reflectance distribution function
• Vraća odnos izmedju količine svetla iz upadnog pravca i količine svetla na izlaznom pravcu
• Opisuje materijal (njegovo ponašanje pod različitim uslovima)
13. TIPOVI MATERIJALA
• Difuzni (mat)
• Odbijanje svetla podjednako verovatno u svim
pravcima
• Glossy (mutne, do umereno sjajne)
• Odbijanje svetla uglavnom oko spekularnog
pravca
• Spekularne (veoma sjajne, reflektujuće)
• Savršeno odbijeno svetlo
Nismo računali:
• Refrakciju
• Apsorpciju
• Transmisiju
14. MONTE CARLO INTEGRACIJA
• U opštem slučaju treba da integralimo (akumuliramo) dolazeće svetlo iz svih pravaca nad hemisferom
• Tehnički to ne možemo izvesti
• Integral treba aproksimirati
• Monte Carlo aproksimacija (stohazička)
• MC je metod numeričke integracija korišćenjem
slučajnih brojeva
• Bazira se na pravilu velikih brojeva
15. MCI & GI
• Mi pokušavamo da integralimo celu hemisferu
• Tehnički ne možemo to uraditi, te radimo aproksimaciju dovoljnim brojem sample-ova
• Posmatramo svaku tačku kao da je izvor svetla i ima uticaj na svaku drugu tačku
• Globalna iluminacija
• Svaka tačka se zbog svetla koje izlazi/se odbija sa nje se može posmatrati kao izvor svetla
• Sve osvetljava sve ostalo, pa čak i samo sebe osvetljava indirektno
17. TIPOVI MATERIJALA
• Kako modelovati različite tipove materijala kod PT?
• Iznenadjujuće jednostavno!
• Poslati više zraka tako da aproksimiramo celu hemisferu i
onda proceniti rezultate
• Dfiuzne – poslati zraka
• Glossy – poslati nekoliko zraka i uzeti srednju vrednost
• Spekularne – poslati samo jedan, reflektovan zrak
• Refrakcija – poslati samo jedan, refraktovan zrak
18. Monte Carlo problemi:
• Rešava problem, ali je rezultat veoma zavisan od broja sample-ova i distribucije istih
• Često se ne dodje do svetla pa rezultat bude jako loš jer kontribucija GI bez nalaženja svetla na kraju
path-a je jako mala ili nepostojeća
• Delimična rešenja: importance sampling, stratified sampling, BDPT, MLT, photon mapping
19. MLT I BDPT
• Metropolis Light Transport (MLT):
iskoristiti putanje koje dovode do svetla,
sto cesce mozemo
• Bidirectional Path Tracing (BDPT):
raditi PT od oka; raditi PT od svetla; spojiti
ta dva
20. PHOTON MAPPING
• Poslati fotone od svetla
• Ispratiti gde završe i kakve su ima
krajnje osobine (noja)
• Rasporediti ih u spatijalnu strukturu
radi bržeg pristupa tokom čitanja
• Tokom računanja GI, uzeti lokalne
fotone i izračunati njihov doprinos
• Veoma spora tehnika, zahteva veliki
broj fotona i velike strukture
• Veoma, veoma retko u online impl.
21. • Računa na to da je GI sporopromenljiva funkcija
• PM je odličan za kaustiku
22. ACCELERATION STRUCTURES
• Računanje preseka zraka i primitive je skupo
• 90% vremena odlazi na računanje preseka
• Ogromna verovatnoća da će zrak promašiti primitivu i onda je svo računanje uzaludno
• Treba minimizovati broj testiranja preseka -> acc structures
• BVH, K-d tree, Octree
23. BOUNDING VOLUME HIERARCHY (BVH)
• Struktura stable
• Svaki roditelj predstavlja BV za svu njegovu decu
• Jedan čvor u stablu može minimalno obuhvatati jednu primitivu
26. PT - PREDNOSTI
• Laka, jednostavna, brza implementacija (smallpt)
• PBR (physically based rendering) – fizički tačne kalkulacije
• Svi mogući tipovi materijala: difuzni, refraktivni, reflektivni, mutni (glossy), providni/apsorbujući (SSS)
• Globalna iluminacija (indirektna iluminacija)
• Visoko parelelan problem – moguće GPGPU/distributed implementacije
• Moze da bude veoma robustan kod
27. PT - MANE
• Jako, jako skupo računanje, te se uglavnom koristi za offline renderovanje
• Avatar: jedan mesec, 8GB/s, na 40k jezgara, 104 PB RAM (jedan frame na svakih nekoliko sati)
• Problem sa noise-om, potrebno je puno sample-ova za lep i noise-free rezultat
• Za lepu GI je potrebno puno sample-ova
• Trenutni GPU hw nije konstruisan za PT već za rasterizaciju, što otežava prelazak rendering engina na PT
algoritme
28. KEY TAKEAWAYS
• PT je PBR algoritam, veoma lak za implementaciju, veoma spor
• Napredniji od rasterizacije
• Funkcioniše po principu nalaženja preseka zraka iz kamere i scene, i računanja osvetljenja (boje)
• GI se aproksimira Monte Carlo metodom
• BRDF opisuje materijal i koristi se pri računanju iluminacije
30. IMPLICITNE POVRSI
• Implicitne površi/figure su definisane jednačinom oblika f(x,y,z) = 0
• Za zadati zrak se ne može odrediti tačan presek, eksplicitno
• Ali, za zadatu tačku u prostoru se može odrediti da li pripada objektu ili ne
• Umesto eksplicitnog računanja preseka zraka i objekta, mi dakle imamo potrebu da ispitamo da li se
neka tačka nalazi ili ne unutar objekta
• Dva načina:
• Ići uvek konstantu udaljenost od početka zraka i ispitivati tačke
• Ići nekonstantnim koracima po zraku i ispitivati tačke (binarna pretraga ili sferično)
33. DISTANCE FIELDS
• Omogućavaju path tracing
• Veoma, veoma jeftin AO
• Veoma jeftine senke
• Prilično lake transformacije objekata (translacija, rotacija, torzija)
• Koriste se dosta u demosceni, ShaderToy primerima
http://www.iquilezles.org/www/articles/raymarchingdf/raymarchingdf.htm
34.
35. LENS EFFECTS: DOF (+BOKEH)
• DOF (depth-of-field) je efekat koji se javlja zbog
nefokusiranosti sočiva
• Ispoljava se kao zamućenje
• Jako se lako simulira u PT rendererima, tako što se zrak
kroz piksel ne formira samo tačno kroz centar piksela
već se razbaca po prostoru koji je veličine DOF efekta
za taj piksel
36. BOKEH
• Oblik DOF zavisi od oblika kroz koji ulazi svetlost
• Oblici su uglavnom kružni, heksagonalni ili oktagonalni
37. MOTION BLUR
• Kada uslikamo sliku, aparat prikuplja neko vreme
osvetljenje, za to vreme je moguće da se neki od
objekata u sceni pomere
• Ti objekti će efektivno slati fotone sa različite pozicije u
sceni, time praktično mutiti sliku -> zamućenje zbog
pomeranja (motion blur)
• Ovaj efekat uglavnom nepoželjan u fotografiji ipak
predstavlja veoma bitan deo naše percepcije prostora i
objekata u njemu
38. MOTION BLUR
• U PT rendererima se lako realizuje tako što
se zraci kroz piksel razbacaju duž vektora
kretanja objekta
Editor's Notes
O cemu cu pricati, odakle ideja, cemu je zamena, prednosti i mane.
Zasto sam izabrao temu -> diplomski
Cilj je da izadjete sa predavanja i imate konceptualno razumevanje PT i da mozete da se upustite u diskusiju ako vam neko spomene tu temu.
U grafici se bavimo sintezom slika, ali st aje svetlo uopste?EM -> interaguje sa cepicima na retini.
Dualna priroda -> fotoni.
Foton mozemo logicki modelovati kroz kroz kod.
Primeri stvaranja svetla u npr lampama.
Whitted raytracer: prati se zrak kroz pikselZrak se moe apsorbovati, reflektovati ili prelomiti.
Uvek se testira zaklonjenje.
GI – sve osvetljava sveGlossy – nisu povrsi samo savrseno reflektujuce, refraktivne ili difuzne, I u stvari, vecina je nesto izmedju
Soft shadows – senke u prirodi su ovek soft
AA – zelimo aa iz logicnih razloga
Lens effects – simulacija efekata sa kamerom je bitna za dozivljaj I percepciju realizma I pozicija objekata (dof, bokeh, motion blur)
Najvise nas interesuje GI !!!!
Sta je boja objekta, kako se racuna, sta predstavlja? -> rendering equation
Zavisno od talasne duzine, materijala objekta, upadnog svetla I uglova ulaza I izlaza
Objasniti naziv: - bidirectional – ili je distribucija na izlazu za zadati ulaz ili izlaz za zadate ulaze
- reflectance – odnos ulaznog I izlaznog svetla
- distribution – funkcija odnosa koeficijanata odnosaPre sve odnos refleksije apsorpcije/refleksije.
Difuzno – apsorbuje
Reflektivno – refleksijaBRDF zavisi od talasne duzine, ali mi uglavnom modelujemo BRDF za RGB komponente boje.
Uzimanje odbiraka I racunanje integrala aproksimacijom odnosa odbiraka unutar f-je I van nje.
Sto vise odbiraka -> preciznije.
BRDF – bidirectional deo -> na osnovu njega se modeluju ovakvi materijali
Ako znamo da nam vise svetla dolazi iz nekog pravca, vise cemo zraka slati u tom pravcu.Ako znamo da nam je veci uticaj svetla iz nekog pravca, onda cemo vise vrednovati taj pravac od ostalih.