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SE 313 – Computer Graphics. Lecture 12: Lighting and Materials Lecturer: Gazihan Alankuş. Projects. Weekly reports Video Sources Final demo. Projects. Weekly reports Help me understand your own contribution Video Sources Final demo. Projects. Weekly reports Video

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Se 313 computer graphics

SE 313 – Computer Graphics

Lecture 12: Lighting and Materials

Lecturer: GazihanAlankuş


Projects
Projects

  • Weekly reports

  • Video

  • Sources

  • Final demo


Projects1
Projects

  • Weekly reports

    • Help me understand your own contribution

  • Video

  • Sources

  • Final demo


Projects2
Projects

  • Weekly reports

  • Video

    • Prepare a video that demonstrates your project

    • Example: https://www.youtube.com/watch?v=auurLcPFGrs&list=PL0E431E2DD85623D5&index=6

    • Should include:

      • A title scene with your names, IEU, SE 313, my name

      • Project description and demonstration

      • Between 2-5 minutes

    • Upload to YouTube with this text(text in [brackets] are optional):

      • Term project for SE 313 Computer Graphics in İzmir University of economics. [your names (optional)] İzmir EkonomiÜniversitesi SE 313 BilgisayarGrafiğidönemprojesi. [your names (optional)]

  • Sources

  • Final demo


Projects3
Projects

  • Weekly reports

  • Video

  • Sources

    • Give me all your source files

    • Include a README file on how to use them

      • Step-by-step instructions

      • Versions of software that you used

      • External factors

        • If you had external help (downloaded models and textures, help you received from someone else, etc.), clearly write them.

        • Was this a project that was a joint project with some other class? If so, write it down.

        • If you don’t do these, you claim that it was all your work and was for this class only. If I prove that it wasn’t, you have cheated and will be punished according to university rules.

  • Final demo


Projects4
Projects

  • Weekly reports

  • Video

  • Sources

  • Final demo

    • Set up a half-hour meeting with me

    • The last day for the meeting is 18th of January

      • My available times may be filled before that. Be quick and try to find a time.

    • Send everything (video, sources, etc.) me 24 hours before that


Lighting and materials
Lighting and Materials

  • Lighting

    • Real-time (local illumination)

    • Better (global illumination)

  • Materials and surface detail

    • Normals

    • Materials


Lighting and materials1
Lighting and Materials

  • Lighting

    • Real-time (local illumination)

    • Better (global illumination)

  • Materials and surface detail

    • Normals

    • Materials


Lighting
Lighting

  • Projecting 3D geometry into 2D is not enough.

Projecting the edges only

Projecting the faces

Copying the object’s colors in the 2D projection does not look good


Lighting1
Lighting

  • We see objects through light bouncing from them

  • We see different tones according to the way light bounces

  • Computers need to simulate this to create realistic pictures


Lighting2
Lighting

  • Simulating light is very difficult. There can be infinite number of rays coming from a light source. We need something fast!


Lighting3
Lighting

  • Observation: if the light can bounce directly from the light source to the eye, the surface looks lighter


Lighting4
Lighting

  • Observation: if the light cannot bounce directly, then the face looks darker

  • We use these observations to simulate lighting

  • We use the normal vector to determine the orientation of the face


Two types of lighting
Two types of lighting

  • Diffuse reflection

    • We see darker color even if light does not bounce directly to the eye

  • Specular reflection

    • We only see color when light bounces directly to the eye


Ambient lighting
Ambient lighting

  • There is so much light that comes from the sun, light bounces from everything in the environment

  • Even if you are in a closed room in daytime, there is light in the environment



Emission
Emission

  • Emission is the fourth type of lighting

  • Simulates objects that emit light by themselves (if it’s a lamp, for example)



Simulating lighting in real time
Simulating lighting in real time

  • These four types of light calculations (ambient, diffuse, specular, emission) help us simulate lighting in computers in real-time.

  • This way we can have video games that look real and react instantly


Lighting and materials2
Lighting and Materials

  • Lighting

    • Real-time (local illumination)

    • Better (global illumination)

  • Materials and surface detail

    • Normals

    • Materials


Global illumination
Global Illumination

  • Simulating light locally is an approximation. Light bouncing from nearby objects is ignored.

  • There are algorithms to simulate light better.


Radiosity
Radiosity

  • Relationships between faces of polygons are computed to see whether they would illuminate or shade each other

  • Slower than local illumination, better results


Ray tracing
Ray tracing

  • Light is reversible

  • Rather than simulating the actual lights, trace light rays that would come to the eye

  • Start from the eye and see whether you reach a light source after bouncing on objects

  • Slower than radiosity. Very real-looking results.


How they are used in practice
How they are used in practice

Local Illumination

Global Illumination

Batch applications

Movies

The image has to look very real

Renders slowly

Render farms with many supercomputers are used for long movies

What you see in Blender Render view

  • Real-time applications

  • Video Games

  • The image does not have to be very realistic

  • Renders very quickly

  • What you see in Blender 3D view


Lighting and materials3
Lighting and Materials

  • Lighting

    • Real-time (local illumination)

    • Better (global illumination)

  • Materials and surface detail

    • Normals

    • Materials


Normals
Normals

  • Surface normals determine the color tones that the surface will have because of lights


Normal mapping
Normal Mapping

  • Surface normals determine the color tones that the surface will have because of lights

  • Surfaces with such detail requires too much geometric detail and renders slowly.

  • We fake it by using normals from a detailed model on a non-detailed model


Normal mapping1
Normal Mapping

  • With normal mapping, you can have a mesh with less detail that looks like another mesh with more detail


Lighting and materials4
Lighting and Materials

  • Lighting

    • Real-time (local illumination)

    • Better (global illumination)

  • Materials and surface detail

    • Normals

    • Materials


Materials
Materials

  • Things that determine the color of a surface

    • Properties of lights

    • Properties of surfaces


Materials1
Materials

  • Things that determine the color of a surface

    • Properties of lights

      • Position

      • Colors and intensities for ambient, diffuse, specular components

    • Properties of surfaces

      • Normals

      • Colors for how ambient, diffuse and specular components will be reflected

      • Emission


Materials2
Materials

  • Matching properties of the light and the surface are multiplied together

Diffuse color of the light

Diffuse color of the material

Visible diffuse color on the surface

LRLGLB

MRMGMB

SRSGSB

Red light

(1, 0, 0)

White material

(1, 1, 1)

Red surface

(1, 0, 0)


Next week
Next week

  • We will practice these in Blender next week

  • Now we will have a lab that you will be graded in


Lab

  • Modeling

  • Texturing


Lab modeling
Lab: Modeling

  • Starting from a cube, model this table.


Lab modeling1
Lab: Modeling

  • Model the legs by subdividing the bottom face, extrude individually, scale, translate, extrude

  • Model the book on the table by creating the rectangle by cutting the edges one by one using the knife tool. Then, extrude it up.


Lab modeling2
Lab: Modeling

  • Model the drawer using extrude.

  • After taking the drawer out, extrude inwards to create the inside of the drawer.


Lab texturing
Lab: Texturing

  • Open the redwood texture in the main uv mapping so that the whole model has the redwood texture.


Lab texturing1
Lab: Texturing

  • Map the book cover on the book cover on top of the table.

  • Create a separate UV map for the book and name it “book”

  • Map the book image in that UVMap

  • Using the clone brush, copy that to the main texture


Lab texturing2
Lab: Texturing

  • Create a separate UV map for the inside of the drawer and name it “drawer”.

  • Map the junk in it


Lab texturing3
Lab: Texturing

  • Use the clone brush to paint into the main UV map from the drawer UV map

  • Leave some empty places to give a dirty look.


Lab bonus
Lab: Bonus

  • Bonus1: Use other wood textures to give a more detailed view to the table

  • Bonus2: create other geometry on top of the table and texture them with images you find on the internet


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