Lighting Workshops Week2

 Post Process Volume

Bloom

    There's already a little bloom by default, turn it off for now so that we get the most contrast

Exposure

    Exposure Compensation is how much exposure Unreal is pushing for you. You can have it either on 1 or 0. 

Chromatic Aberration

    When you take a picture with a not great lens, you can see on the edges of objects the red, yellow, and blue values are being split. Use it minimaly. 

Color Grading 

Temperature: Changing the temp can push it blue or orange. Changing the tint will push it either more purple or more green. Temperature Type is either you focus on changing the color temperature, or white balence (color temperature and intensity). 

Adding an HDRI

    Download an exr and hdri from Polyhaven. Import them into Unreal, you will have to make sure the exr and hdri have different names or else one of them will fail to import. Create a Sky Light. Underneath Light> Real Time Capture turn off. and change the source type to SLS specified cubemap, and you can set the cubemap to the hdri you just imported. 

    

Creating Spheres to test the light

    Make a material with parameters to change the color, roughness, and metalness. 

Black Sphere

• Color: 0.04 (albedo for charcoal, nothing darker than that
• Metal: 0.0
• Roughness: 0.3

White Sphere

• Color: 0.85 (albedo for snow)
• Metal: 0.0
• Roughness: 0.3

Middle Grey

• Color: 0.18 
• Metal: 0.0
• Roughness: 0.3

Chrome

• Color: 0.9 (your base color is deciding how bright your reflection is, if doesn't ever reflect a color it reflects the environment around it)
• Metal: 1.0
• Roughness: 0.05

Sky Light Lower Color

    By default, the lower color of the sky light is totally black. you can change this to include the rest of your hdri by looking for lower and unchecking 'Lower Hemisphere is solid color'

    You can see it best in the chrome ball.

HDRI Backdrop

    This projects the hue map of the hdri. It's a projection, so the more you move away from its center the more stretched out it will be.

Camera settings

Filmback

    The film back is talking about the sensor. The presets are based off of real cameras. You can change however wide or tall your render is. 

Focal Length

    

Lower Focal Length means more depth. A higher focal length means everything gets flatter, but you can also get a lot of blur in out of focus areas. 

 Extra Notes taken from the video Intro to Physically Based Lighting and Cinematics - Lighting for Videogames by Visual Tech Artist

    

    You can see a histogram of your values by going into show>Visualize>HDR (Eye Adaption). A steeper curve means more contrast.

    A camera's aperture is the opening through which light passes through the camera, the wider the opening the more light that is exposed. It also affects how big the depth of field is.