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Pinhole Camera
- The simplest camera model — all rays pass through a single point (the pinhole)
- No depth of field — everything is in focus
- Parameters
position — camera origin in world spaceforward — direction the camera looks (normalized)up — world up vector (used to compute right vector)fov — vertical field of view (degrees or radians)aspect_ratio — width / height
- Building the camera basis
- Viewport dimensions
viewport_height = 2 * tan(fov / 2) (at unit focal distance)viewport_width = viewport_height * aspect_ratio
- Generating a ray for pixel
(i, j) in an (W, H) image
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Thin Lens Camera (Depth of Field)
- Real cameras have a lens with finite aperture
- Objects at the focal distance are sharp; others are blurry (bokeh)
- Parameters (in addition to pinhole)
aperture — lens diameter (larger = more blur)focus_distance — distance to the focal plane
- Algorithm
- Sample a random point on the lens disk:
lens_offset = aperture/2 * random_disk()
- Compute the focus point:
focus_point = position + focus_distance * ray_dir
- New ray origin:
origin = position + lens_offset.x * right + lens_offset.y * up
- New ray direction:
direction = normalize(focus_point - origin)
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Field of View
- Vertical FOV: angle from bottom to top of the image
- Horizontal FOV:
2 * atan(tan(vfov/2) * aspect_ratio)
- Common values: 60° (telephoto feel), 90° (wide), 120° (very wide)
- In Godot:
Camera3D.fov is vertical FOV in degrees
- Relationship to focal length:
fov = 2 * atan(sensor_height / (2 * focal_length))
- 50mm lens on 35mm sensor:
fov ≈ 39.6° (normal lens)
- 24mm lens:
fov ≈ 73.7° (wide angle)
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Camera in Vulkan Ray Tracing
- Pass camera data as a uniform buffer to the ray generation shader
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Motion Blur
- Shutter opens for a time interval
[t0, t1]
- Sample a random time
t = lerp(t0, t1, random())
- Evaluate object transforms at time
t
- Requires per-object velocity data or interpolated transforms
- In path tracing: each ray sample uses a different time → natural motion blur