### Configuring and observing with a MeshCamera

Source: http://www.raysect.org/api_reference/optical/observers.html

Example demonstrating the setup of a MeshCamera using a mesh primitive, a power pipeline, and an adaptive sampler.

```python
>>> from raysect.primitive import Mesh
>>> from raysect.optical import World
>>> from raysect.optical.material import AbsorbingSurface
>>> from raysect.optical.observer import MeshCamera, PowerPipeline1D, MonoAdaptiveSampler1D
>>>
>>> world = World()
>>>
>>> mesh = Mesh.from_file("my_mesh.rsm", material=AbsorbingSurface(), parent=world)
>>>
>>> power = PowerPipeline1D()
>>> sampler = MonoAdaptiveSampler1D(power, fraction=0.2, ratio=25.0, min_samples=1000, cutoff=0.1)
>>> camera = MeshCamera(mesh,
                        surface_offset=1e-6,  # launch rays 1mm off surface to avoid intersection with absorbing mesh
                        pipelines=[power],
                        frame_sampler=sampler,
                        parent=world,
                        spectral_bins=1,
                        min_wavelength=400,
                        max_wavelength=740,
                        pixel_samples=250)
>>> camera.observe()
```

--------------------------------

### Install Raysect from source

Source: http://www.raysect.org/_sources/installation.rst.txt

Use this method if pip is unavailable or if you are working with a local copy of the source code.

```bash
python setup.py install
```

--------------------------------

### RenderEngine.run

Source: http://www.raysect.org/_modules/raysect/core/workflow.html

Starts the render engine to execute a list of tasks using provided render and update functions.

```APIDOC
## RenderEngine.run

### Description
Starts the render engine executing the requested tasks. The engine distributes tasks to workers, which execute the render function and return results to be processed by the update function.

### Parameters
- **tasks** (list) - Required - List of user defined tuples that describe the task to execute.
- **render** (object) - Required - Callable python object that executes the tasks. Signature: def render(task, *render_args, **render_kwargs)
- **update** (object) - Required - Callable python object that is called following a render task to update internal state. Signature: def update(results, *update_args, **update_kwargs)
- **render_args** (tuple) - Optional - Additional arguments to pass to user defined render function.
- **render_kwargs** (dict) - Optional - Additional keyword arguments to pass to user defined render function.
- **update_args** (tuple) - Optional - Additional arguments to pass to user defined update function.
- **update_kwargs** (dict) - Optional - Additional keyword arguments to pass to user defined update function.
```

--------------------------------

### Cornell Box Scene Setup

Source: http://www.raysect.org/demonstrations/observers/cornell_box.html

This script initializes the scene graph, defines material properties using interpolated spectral functions, and constructs the box geometry.

```python
from matplotlib.pyplot import *

from raysect.primitive import Sphere, Box
from raysect.optical import World, Node, translate, rotate, Point3D
from raysect.optical.material import Lambert, UniformSurfaceEmitter
from raysect.optical.library import *
from raysect.optical.observer import PinholeCamera
from raysect.optical.observer import RGBPipeline2D, BayerPipeline2D, PowerPipeline2D
from raysect.optical.observer import RGBAdaptiveSampler2D


"""
Cornell Box Demo
================

This demo renders a variant of the classic Cornell Box scene.

To the original Cornell Box see:

    http://www.graphics.cornell.edu/online/box/data.html

The wall colours and light spectrum used in this demo are the values measured
for the physical Cornell Box.
"""

# define reflectivity for box surfaces
wavelengths = array(
    [400, 404, 408, 412, 416, 420, 424, 428, 432, 436, 440, 444, 448, 452, 456, 460, 464, 468, 472, 476, 480, 484, 488,
     492, 496, 500, 504, 508, 512, 516, 520, 524, 528, 532, 536, 540, 544, 548, 552, 556, 560, 564, 568, 572, 576, 580,
     584, 588, 592, 596, 600, 604, 608, 612, 616, 620, 624, 628, 632, 636, 640, 644, 648, 652, 656, 660, 664, 668, 672,
     676, 680, 684, 688, 692, 696, 700])

white = array(
    [0.343, 0.445, 0.551, 0.624, 0.665, 0.687, 0.708, 0.723, 0.715, 0.71, 0.745, 0.758, 0.739, 0.767, 0.777, 0.765,
     0.751, 0.745, 0.748, 0.729, 0.745, 0.757, 0.753, 0.75, 0.746, 0.747, 0.735, 0.732, 0.739, 0.734, 0.725, 0.721,
     0.733, 0.725, 0.732, 0.743, 0.744, 0.748, 0.728, 0.716, 0.733, 0.726, 0.713, 0.74, 0.754, 0.764, 0.752, 0.736,
     0.734, 0.741, 0.74, 0.732, 0.745, 0.755, 0.751, 0.744, 0.731, 0.733, 0.744, 0.731, 0.712, 0.708, 0.729, 0.73,
     0.727, 0.707, 0.703, 0.729, 0.75, 0.76, 0.751, 0.739, 0.724, 0.73, 0.74, 0.737])

green = array(
    [0.092, 0.096, 0.098, 0.097, 0.098, 0.095, 0.095, 0.097, 0.095, 0.094, 0.097, 0.098, 0.096, 0.101, 0.103, 0.104,
     0.107, 0.109, 0.112, 0.115, 0.125, 0.14, 0.16, 0.187, 0.229, 0.285, 0.343, 0.39, 0.435, 0.464, 0.472, 0.476, 0.481,
     0.462, 0.447, 0.441, 0.426, 0.406, 0.373, 0.347, 0.337, 0.314, 0.285, 0.277, 0.266, 0.25, 0.23, 0.207, 0.186,
     0.171, 0.16, 0.148, 0.141, 0.136, 0.13, 0.126, 0.123, 0.121, 0.122, 0.119, 0.114, 0.115, 0.117, 0.117, 0.118, 0.12,
     0.122, 0.128, 0.132, 0.139, 0.144, 0.146, 0.15, 0.152, 0.157, 0.159])

red = array(
    [0.04, 0.046, 0.048, 0.053, 0.049, 0.05, 0.053, 0.055, 0.057, 0.056, 0.059, 0.057, 0.061, 0.061, 0.06, 0.062, 0.062,
     0.062, 0.061, 0.062, 0.06, 0.059, 0.057, 0.058, 0.058, 0.058, 0.056, 0.055, 0.056, 0.059, 0.057, 0.055, 0.059,
     0.059, 0.058, 0.059, 0.061, 0.061, 0.063, 0.063, 0.067, 0.068, 0.072, 0.08, 0.09, 0.099, 0.124, 0.154, 0.192,
     0.255, 0.287, 0.349, 0.402, 0.443, 0.487, 0.513, 0.558, 0.584, 0.62, 0.606, 0.609, 0.651, 0.612, 0.61, 0.65, 0.638,
     0.627, 0.62, 0.63, 0.628, 0.642, 0.639, 0.657, 0.639, 0.635, 0.642])

white_reflectivity = InterpolatedSF(wavelengths, white)
red_reflectivity = InterpolatedSF(wavelengths, red)
green_reflectivity = InterpolatedSF(wavelengths, green)

# define light spectrum
light_spectrum = InterpolatedSF(array([400, 500, 600, 700]), array([0.0, 8.0, 15.6, 18.4]))

# set-up scenegraph
world = World()

# enclosing box
enclosure = Node(world)

e_back = Box(Point3D(-1, -1, 0), Point3D(1, 1, 0),
             parent=enclosure,
             transform=translate(0, 0, 1) * rotate(0, 0, 0),
             material=Lambert(white_reflectivity))

e_bottom = Box(Point3D(-1, -1, 0), Point3D(1, 1, 0),
               parent=enclosure,
               transform=translate(0, -1, 0) * rotate(0, -90, 0),
               # material=m)
               material=Lambert(white_reflectivity))

e_top = Box(Point3D(-1, -1, 0), Point3D(1, 1, 0),
            parent=enclosure,
            transform=translate(0, 1, 0) * rotate(0, 90, 0),
            material=Lambert(white_reflectivity))

e_left = Box(Point3D(-1, -1, 0), Point3D(1, 1, 0),
             parent=enclosure,
             transform=translate(1, 0, 0) * rotate(-90, 0, 0),
             material=Lambert(red_reflectivity))

e_right = Box(Point3D(-1, -1, 0), Point3D(1, 1, 0),
              parent=enclosure,
              transform=translate(-1, 0, 0) * rotate(90, 0, 0),
              material=Lambert(green_reflectivity))

# ceiling light
light = Box(Point3D(-0.4, -0.4, -0.01), Point3D(0.4, 0.4, 0.0),
            parent=enclosure,
            transform=translate(0, 1, 0) * rotate(0, 90, 0),
            material=UniformSurfaceEmitter(light_spectrum, 2))
```

--------------------------------

### Install Raysect via pip

Source: http://www.raysect.org/_sources/index.rst.txt

Use this command to install the Raysect package and its dependencies.

```bash
pip install raysect
```

--------------------------------

### Run Raysect tests

Source: http://www.raysect.org/_sources/installation.rst.txt

Execute the test suite using the nose framework within the source directory to verify the installation.

```bash
nosetests
```

--------------------------------

### RenderEngine run method

Source: http://www.raysect.org/_modules/raysect/core/workflow.html

The method used to start the render engine with tasks and processing functions.

```python
def run(self, tasks, render, update, render_args=(), render_kwargs={}, update_args=(), update_kwargs={}):
    """
    Starts the render engine executing the requested tasks.

    :param list tasks: List of user defined tuples that describe the task to execute.
    :param object render: Callable python object that executes the tasks.
    :param object update: Callable python object that is called following a render task and must be
      used to update the internal state of the object requesting work.
    :param tuple render_args: Additional arguments to pass to user defined render function.
    :param tuple render_kwargs: Additional keyword arguments to pass to user defined render function.
    :param tuple update_args: Additional arguments to pass to user defined update function.
    :param tuple update_kwargs: Additional keyword arguments to pass to user defined update function.
    """
    raise NotImplementedError("Virtual method must be implemented in sub-class.")
```

--------------------------------

### Execute Multicore and Serial Engines

Source: http://www.raysect.org/_modules/raysect/core/workflow.html

Example usage of the Job class to compare performance between SerialEngine and MulticoreEngine.

```python
if __name__ == '__main__':

    class Job:

        def __init__(self, engine=None):
            self.total = 0
            self.engine = engine if engine else MulticoreEngine()

        def run(self, v):
            self.total = 0
            self.engine.run(list(range(v)), self.render, self.update, render_args=(10000,))
            return self.total

        def render(self, task, count):
            sum = 0
            for i in range(count):
                sum += 1 / count
            return sum

        def update(self, result):
            self.total += result

    n = 20000

    t = time.time()
    j = Job(SerialEngine())
    print(j.run(n), time.time() - t)

    t = time.time()
    j = Job(MulticoreEngine())
    print(j.run(n), time.time() - t)
```

--------------------------------

### Initialize and observe with a FibreOptic

Source: http://www.raysect.org/api_reference/optical/observers.html

Demonstrates configuring a FibreOptic observer with multiple pipelines and specific physical parameters.

```python
>>> from raysect.optical.observer import FibreOptic, RadiancePipeline0D, PowerPipeline0D
>>>
>>> power = PowerPipeline0D()
>>> radiance = RadiancePipeline0D()
>>> fibre = FibreOptic([power, radiance], acceptance_angle=10, radius=0.0005,
                        spectral_bins=500, pixel_samples=1000,
                        transform=translate(0, 0, -5), parent=world)
>>> fibre.observe()
```

--------------------------------

### Initialize and observe with a Pixel observer

Source: http://www.raysect.org/api_reference/optical/observers.html

Demonstrates setting up a Pixel observer with a PowerPipeline0D and performing an observation.

```python
>>> from raysect.optical import World
>>> from raysect.optical.observer import Pixel, PowerPipeline0D
>>>
>>> world = World()
>>> power = PowerPipeline0D(accumulate=False)
>>> observing_plane = Pixel([power], x_width=2.0, y_width=2.0,
                            min_wavelength=400, max_wavelength=720,
                            spectral_bins=1, pixel_samples=250,
                            parent=world, transform=rotate(0, 0, 0)*translate(0, 0, -1))
>>> observing_plane.observe()
```

--------------------------------

### Get Vector3D Length

Source: http://www.raysect.org/api_reference/core/points_and_vectors.html

Retrieves the length of the vector.

```python
>>> a = Vector3D(1, 1, 1)
>>> a.length
1.7320508075688772
```

--------------------------------

### Initialize camera and film settings

Source: http://www.raysect.org/demonstrations/observers/cornell_box_with_camera.html

Sets up the camera node, pinhole, and CCD array with specific ray-tracing parameters.

```python
camera = Node(parent=world, transform=translate(0, 0, -3.3))
pinhole = Sphere(0.0005, camera, transform=translate(0, 0, 0), material=NullMaterial())
film = TargetedCCDArray(targeted_path_prob=1.0, targets=[pinhole], width=0.1, pixels=(512, 512), parent=camera,
                         transform=translate(0, 0, -0.1207), pipelines=pipelines)
film.frame_sampler = sampler
film.pixel_samples = 250
film.spectral_bins = 15
film.spectral_rays = 1
film.ray_importance_sampling = True
film.ray_important_path_weight = 0.25
film.ray_max_depth = 500
film.ray_extinction_min_depth = 3
film.ray_extinction_prob = 0.01
```

--------------------------------

### Get Vector2D Length

Source: http://www.raysect.org/api_reference/core/points_and_vectors.html

Retrieve the magnitude of the vector.

```python
>>> a = Vector2D(1, 1)
>>> a.length
1.4142135623730951
```

--------------------------------

### important_direction_sample(origin)

Source: http://www.raysect.org/api_reference/optical/main_optical_classes.html

Gets a sample direction of an important primitive.

```APIDOC
## important_direction_sample(origin)

### Description
Get a sample direction of an important primitive.

### Parameters
- **origin** (Point3D) - Required - The point from which to sample.

### Returns
- **Vector3D** - The vector along which to sample.
```

--------------------------------

### Access Point3D Coordinates

Source: http://www.raysect.org/api_reference/core/points_and_vectors.html

Get or set coordinates using index notation.

```python
>>> a = Point3D(1, 0, 0)
>>> a[0]
1
```

```python
>>> a = Point3D(1, 0, 0)
>>> a[1] = 2
>>> a
Point3D(1.0, 2.0, 0.0)
```

--------------------------------

### Initialize UnityVolumeEmitter

Source: http://www.raysect.org/api_reference/optical/optical_volumes.html

Demonstrates setting up a scene with a sphere using the UnityVolumeEmitter material.

```python
>>> from raysect.primitive import Sphere
>>> from raysect.optical import World
>>> from raysect.optical.material import UnityVolumeEmitter
>>>
>>> # set-up scenegraph
>>> world = World()
>>> emitter = Sphere(radius=0.01, parent=world, material=UnityVolumeEmitter())
```

--------------------------------

### Configure and Run a PinholeCamera

Source: http://www.raysect.org/api_reference/optical/observers.html

Demonstrates initializing a PinholeCamera with a PowerPipeline2D, setting camera transforms, and triggering the observation process.

```python
>>> from raysect.core import translate
>>> from raysect.optical import World
>>> from raysect.optical.observer import PinholeCamera, PowerPipeline2D
>>>
>>> power = PowerPipeline2D(display_unsaturated_fraction=0.96, name="Unfiltered")
>>>
>>> camera = PinholeCamera((512, 512), parent=world, pipelines=[power])
>>> camera.transform = translate(0, 0, -3.3)
>>> camera.pixel_samples = 250
>>> camera.spectral_bins = 15
>>>
>>> camera.observe()
```

--------------------------------

### Get Orthogonal Vector3D

Source: http://www.raysect.org/api_reference/core/points_and_vectors.html

Returns a unit vector guaranteed to be orthogonal to the current vector.

```python
>>> a = Vector3D(1, 0, 0)
>>> a.orthogonal()
Vector3D(0.0, 1.0, 0.0)
```

--------------------------------

### Configure camera pipelines and sampler

Source: http://www.raysect.org/demonstrations/observers/cornell_box_with_camera.html

Initializes various imaging pipelines and an adaptive sampler for the camera.

```python
# create and setup the camera
power_unfiltered = PowerPipeline2D(display_unsaturated_fraction=0.96, name="Unfiltered")
power_unfiltered.display_update_time = 15

power_green = PowerPipeline2D(filter=filter_green, display_unsaturated_fraction=0.96, name="Green Filter")
power_green.display_update_time = 15

power_red = PowerPipeline2D(filter=filter_red, display_unsaturated_fraction=0.96, name="Red Filter")
power_red.display_update_time = 15

rgb = RGBPipeline2D(display_unsaturated_fraction=0.96, name="sRGB")

bayer = BayerPipeline2D(filter_red, filter_green, filter_blue, display_unsaturated_fraction=0.96, name="Bayer Filter")
bayer.display_update_time = 15

pipelines = [rgb, power_unfiltered, power_green, power_red, bayer]

sampler = RGBAdaptiveSampler2D(rgb, ratio=10, fraction=0.2, min_samples=500, cutoff=0.05)
```

--------------------------------

### Initialize a UnitySurfaceEmitter

Source: http://www.raysect.org/api_reference/optical/optical_surfaces.html

Demonstrates setting up a sphere with a uniform and isotropic UnitySurfaceEmitter.

```python
>>> from raysect.primitive import Sphere
>>> from raysect.optical import World
>>> from raysect.optical.material import UnitySurfaceEmitter
>>>
>>> # set-up scenegraph
>>> world = World()
>>> emitter = Sphere(radius=0.01, parent=world, material=UnitySurfaceEmitter())
```

--------------------------------

### Initialize and observe with a SightLine

Source: http://www.raysect.org/api_reference/optical/observers.html

Demonstrates setting up a SightLine observer within a world and triggering an observation.

```python
>>> from raysect.optical import World
>>> from raysect.optical.observer import SightLine, PowerPipeline0D
>>>
>>> world = World()
>>> power = PowerPipeline0D(accumulate=False)
>>> los = SightLine([power], min_wavelength=400, max_wavelength=720,
                    parent=world, transform=rotate(0, 0, 0)*translate(0, 0, -1))
>>> los.observe()
```

--------------------------------

### Configure and run a FibreOptic observer

Source: http://www.raysect.org/demonstrations/observers/optical_fibre.html

Sets up a scene with a ground plane, emitter, and sphere, then initializes a FibreOptic observer with multiple data pipelines to perform an observation.

```python
# External imports
import matplotlib.pyplot as plt

# Raysect imports
from raysect.primitive import Sphere, Box
from raysect.optical import World, translate, rotate, Point3D, d65_white
from raysect.optical.material import Lambert, Checkerboard
from raysect.optical.library import schott
from raysect.optical.observer import FibreOptic, PowerPipeline0D, RadiancePipeline0D, SpectralPowerPipeline0D, SpectralRadiancePipeline0D


# Box defining the ground plane
ground = Box(lower=Point3D(-50, -1.51, -50), upper=Point3D(50, -1.5, 50), material=Lambert())

# checker board wall that acts as emitter
emitter = Box(lower=Point3D(-10, -10, 10), upper=Point3D(10, 10, 10.1),
              material=Checkerboard(4, d65_white, d65_white, 0.1, 2.0), transform=rotate(45, 0, 0))

# Sphere
sphere = Sphere(radius=1.5, transform=translate(0, 0.0001, 0), material=schott("N-BK7"))


# 3. Build Scenegraph
# -------------------

world = World()
sphere.parent = world
ground.parent = world
emitter.parent = world


# 4. Observe()
# ------------

plt.ion()
spectral_power = SpectralPowerPipeline0D()
spectral_radiance = SpectralRadiancePipeline0D()
power = PowerPipeline0D()
radiance = RadiancePipeline0D()
fibre = FibreOptic([spectral_power, spectral_radiance, power, radiance], acceptance_angle=10, radius=0.0005,
                   spectral_bins=500, spectral_rays=1, pixel_samples=1000, transform=translate(0, 0, -5), parent=world)
fibre.observe()

plt.ioff()
plt.show()
```

--------------------------------

### Initialize a Point3D

Source: http://www.raysect.org/api_reference/core/points_and_vectors.html

Create a new 3D point instance.

```python
>>> from raysect.core import Point3D
>>> a = Point3D(0, 1, 2)
```

--------------------------------

### Configure Camera and Sampler

Source: http://www.raysect.org/demonstrations/observers/cornell_box.html

Initializes the PinholeCamera with specific sampling and ray tracing parameters.

```python
sampler = RGBAdaptiveSampler2D(rgb, ratio=10, fraction=0.2, min_samples=500, cutoff=0.01)

camera = PinholeCamera((1024, 1024), parent=world, transform=translate(0, 0, -3.3) * rotate(0, 0, 0), pipelines=pipelines)
camera.frame_sampler = sampler
camera.spectral_rays = 1
camera.spectral_bins = 15
camera.pixel_samples = 250
camera.ray_importance_sampling = True
camera.ray_important_path_weight = 0.25
camera.ray_max_depth = 500
camera.ray_extinction_min_depth = 3
camera.ray_extinction_prob = 0.01
```

--------------------------------

### Initialize UniformVolumeEmitter

Source: http://www.raysect.org/api_reference/optical/optical_volumes.html

Demonstrates configuring a sphere with a UniformVolumeEmitter using a constant spectral function.

```python
>>> from raysect.primitive import Sphere
>>> from raysect.optical import World, ConstantSF
>>> from raysect.optical.material import UniformVolumeEmitter
>>>
>>> # set-up scenegraph
>>> world = World()
>>> emitter = Sphere(radius=0.01, parent=world)
>>> emitter.material=UniformVolumeEmitter(ConstantSF(1.0))
```

--------------------------------

### Initialize Point2D

Source: http://www.raysect.org/api_reference/core/points_and_vectors.html

Create a new 2D point instance.

```python
>>> from raysect.core import Point2D
>>>
>>> a = Point2D(1, 1)
```

--------------------------------

### Initialize an AbsorbingSurface

Source: http://www.raysect.org/api_reference/optical/optical_surfaces.html

Demonstrates how to instantiate an AbsorbingSurface and assign it to a primitive within a Raysect world.

```python
>>> from raysect.primitive import Sphere
>>> from raysect.optical import World
>>> from raysect.optical.material import AbsorbingSurface
>>>
>>> # set-up scenegraph
>>> world = World()
>>> absorber = Sphere(radius=0.01, parent=world, material=AbsorbingSurface())
```

--------------------------------

### Initialize a Vector3D

Source: http://www.raysect.org/api_reference/core/points_and_vectors.html

Create a new 3D vector instance.

```python
>>> from raysect.core import Vector3D
>>> a = Vector3D(1, 0, 0)
```

--------------------------------

### Initialize a Checkerboard Emitter

Source: http://www.raysect.org/api_reference/optical/optical_surfaces.html

Demonstrates creating a box with a Checkerboard material emitter.

```python
>>> from raysect.primitive import Box
>>> from raysect.optical import World, rotate, Point3D, d65_white
>>> from raysect.optical.material import Checkerboard
>>>
>>> world = World()
>>>
>>> # checker board wall that acts as emitter
>>> emitter = Box(lower=Point3D(-10, -10, 10), upper=Point3D(10, 10, 10.1), parent=world,
                  transform=rotate(45, 0, 0))
>>> emitter.material=Checkerboard(4, d65_white, d65_white, 0.1, 2.0)
```

--------------------------------

### Initialize and observe with a MeshPixel observer

Source: http://www.raysect.org/api_reference/optical/observers.html

Demonstrates using a triangular mesh as a pixel observer, including setting a surface offset to avoid collision.

```python
>>> from raysect.primitive import Mesh
>>> from raysect.optical import World
>>> from raysect.optical.material import AbsorbingSurface
>>> from raysect.optical.observer import MeshPixel, PowerPipeline0D
>>>
>>> world = World()
>>>
>>> mesh = Mesh.from_file("my_mesh.rsm", material=AbsorbingSurface(), parent=world)
>>>
>>> power = PowerPipeline0D(accumulate=False)
>>> observer = MeshPixel(mesh, pipelines=[power], parent=world,
>>>                      min_wavelength=400, max_wavelength=750,
>>>                      spectral_bins=1, pixel_samples=10000, surface_offset=1E-6)
>>> observer.observe()
```

--------------------------------

### Configure Spectral Filters and Pipelines

Source: http://www.raysect.org/demonstrations/observers/cornell_box.html

Sets up color filters and various imaging pipelines for the camera.

```python
filter_red = InterpolatedSF([100, 650, 660, 670, 680, 800], [0, 0, 1, 1, 0, 0])
filter_green = InterpolatedSF([100, 530, 540, 550, 560, 800], [0, 0, 1, 1, 0, 0])
filter_blue = InterpolatedSF([100, 480, 490, 500, 510, 800], [0, 0, 1, 1, 0, 0])

# create and setup the camera
power_unfiltered = PowerPipeline2D(display_unsaturated_fraction=0.96, name="Unfiltered")
power_unfiltered.display_update_time = 15

power_green = PowerPipeline2D(filter=filter_green, display_unsaturated_fraction=0.96, name="Green Filter")
power_green.display_update_time = 15

power_red = PowerPipeline2D(filter=filter_red, display_unsaturated_fraction=0.96, name="Red Filter")
power_red.display_update_time = 15

rgb = RGBPipeline2D(display_unsaturated_fraction=0.96, name="sRGB")

bayer = BayerPipeline2D(filter_red, filter_green, filter_blue, display_unsaturated_fraction=0.96, name="Bayer Filter")
bayer.display_update_time = 15

pipelines = [rgb, power_unfiltered, power_green, power_red, bayer]
```

--------------------------------

### Using 1D Interpolator

Source: http://www.raysect.org/api_reference/core/functions.html

Demonstrates initializing a 1D interpolator with cubic interpolation and nearest-neighbor extrapolation.

```python
>>> from raysect.core.math.function.float.function1d.interpolate import Interpolator1DArray
>>>
>>> x = np.linspace(-1., 1., 20)
>>> f = np.exp(-x**2)
>>> interpolator1D = Interpolate1DArray(x, f, 'cubic', 'nearest', 1.0)
>>> # Interpolation
>>> interpolator1D(0.2)
0.9607850606581484
>>> # Extrapolation
>>> interpolator1D(1.1)
0.36787944117144233
>>> # Extrapolation out of bounds
>>> interpolator1D(2.1)
ValueError: The specified value (x=2.1) is outside of extrapolation range.
```

--------------------------------

### Initializing scene constants and sphere

Source: http://www.raysect.org/_sources/demonstrations/core/energy_conservation.rst.txt

Define simulation parameters and place the emitting sphere into the world.

```python
samples = 100000

sphere_radius = 0.5
cube_size = 2

min_wl = 400
max_wl = 401

# set-up scenegraph
world = World()
emitter = Sphere(radius=sphere_radius, parent=world)
```

--------------------------------

### Initialize Vector2D

Source: http://www.raysect.org/api_reference/core/points_and_vectors.html

Create a new 2D vector instance.

```python
>>> from raysect.core import Vector2D
>>> a = Vector2D(1, 0)
```

--------------------------------

### Add Observer

Source: http://www.raysect.org/_sources/quickstart_guide.rst.txt

Configure a camera and its sampling parameters for the rendering pipeline.

```python
# processing pipeline (human vision like camera response)
rgb = RGBPipeline2D()

# camera
camera = PinholeCamera(pixels=(512, 512), fov=45, pipeline=[rgb], transform=translate(0, 10, -10) * rotate(0, -45, 0))

# camera - pixel sampling settings
camera.pixel_samples = 250
camera.min_wavelength = 375.0
camera.max_wavelength = 740.0
camera.spectral_bins = 15
camera.spectral_rays = 1
```

--------------------------------

### Load a Mesh from an RSM file

Source: http://www.raysect.org/api_reference/primitives/meshes.html

Demonstrates instantiating a Mesh from an RSM file using the from_file class method, including setting parent, material, and transform properties.

```python
>>> from raysect.optical import World, translate, rotate, ConstantSF, Sellmeier, Dielectric
>>> from raysect.primitive import Mesh
>>>
>>> world = World()
>>>
>>> diamond = Dielectric(Sellmeier(0.3306, 4.3356, 0.0, 0.1750**2, 0.1060**2, 0.0), ConstantSF(1.0))
>>>
>>> mesh = Mesh.from_file("my_mesh.rsm", parent=world, material=diamond,
>>>                       transform=translate(0, 0, 0)*rotate(165, 0, 0))
```

--------------------------------

### Using Arg2D for Coordinate Selection and Arithmetic

Source: http://www.raysect.org/api_reference/core/functions.html

Demonstrates how to use Arg2D to select function arguments and perform basic arithmetic operations on the resulting function objects.

```python
>>> argx = Arg2D("x")
>>> argx(2, 3)
2.0
>>> argy = Arg2D("y")
>>> argy(2, 3)
3.0
>>> squarerx = argx**2
>>> squarerx(2, 3)
4.0
>>> squarery = argy**2
>>> squarery(2, 3)
9.0
```

--------------------------------

### Observe Scene

Source: http://www.raysect.org/_sources/quickstart_guide.rst.txt

Execute the rendering process and display or save the output.

```python
plt.ion()
camera.observe()

plt.ioff()
rgb.save("render.png")
rgb.display()
```

--------------------------------

### Using Arg1D for Identity and Squaring

Source: http://www.raysect.org/api_reference/core/functions.html

Demonstrates using Arg1D to return the input argument and applying mathematical operations to create new function objects.

```python
>>> arg = Arg1D()
>>> arg(2)
2.0
>>> arg(-3.14)
-3.14
>>> squarer = Arg1D()**2
>>> squarer(2)
4.0
>>> squarer(-3.14)
9.8596
```

--------------------------------

### Initialize Spectrum Object

Source: http://www.raysect.org/api_reference/optical/main_optical_classes.html

Creates a new Spectrum instance with specified wavelength bounds and bin count.

```python
>>> from raysect.optical import Spectrum
>>>
>>> spectrum = Spectrum(400, 720, 250)
```

--------------------------------

### Initialize a UniformSurfaceEmitter

Source: http://www.raysect.org/api_reference/optical/optical_surfaces.html

Demonstrates assigning a UniformSurfaceEmitter with a constant spectral function to a sphere.

```python
>>> from raysect.primitive import Sphere
>>> from raysect.optical import World, ConstantSF
>>> from raysect.optical.material import UniformSurfaceEmitter
>>>
>>> # set-up scenegraph
>>> world = World()
>>> emitter = Sphere(radius=0.01, parent=world)
>>> emitter.material=UniformSurfaceEmitter(ConstantSF(1.0))
```

--------------------------------

### Import a Mesh from an OBJ file

Source: http://www.raysect.org/api_reference/primitives/meshes.html

Demonstrates importing a Wavefront OBJ file into a Raysect Mesh, including applying a scaling factor to convert units.

```python
>>> from raysect.optical import World, translate, rotate, ConstantSF, Sellmeier, Dielectric
>>> from raysect.primitive import import_obj
>>>
>>> world = World()
>>>
>>> diamond = Dielectric(Sellmeier(0.3306, 4.3356, 0.0, 0.1750**2, 0.1060**2, 0.0),
>>>                      ConstantSF(1.0))
>>>
>>> bunny_mesh = import_obj("resources/stanford_bunny.obj", scaling=1, parent=world,
>>>                         transform=translate(0, 0, 0)*rotate(165, 0, 0), material=diamond)
```

--------------------------------

### Constructing a custom camera with lens and aperture

Source: http://www.raysect.org/demonstrations/observers/metal_balls_with_lens.html

Sets up a scene with metallic spheres and a camera assembly using a BiConvex lens, aperture, and CCD array.

```python
from matplotlib.pyplot import *

from raysect.optical import World, translate, rotate, Point3D, d65_white, ConstantSF, Node
from raysect.primitive import Sphere, Box, Cylinder, Subtract
from raysect.primitive.lens.spherical import BiConvex
from raysect.optical.library.metal import Gold, Silver, Copper, Titanium, Aluminium, Beryllium
from raysect.optical.material import Lambert, UniformSurfaceEmitter, AbsorbingSurface, NullMaterial
from raysect.optical.library import schott
from raysect.optical.observer import RGBPipeline2D, BayerPipeline2D, TargetedCCDArray, CCDArray, RGBAdaptiveSampler2D
from raysect.optical.colour import ciexyz_x, ciexyz_y, ciexyz_z


world = World()

Sphere(0.5, world, transform=translate(1.2, 0.5001, 0.6), material=Gold())
Sphere(0.5, world, transform=translate(0.6, 0.5001, -0.6), material=Silver())
Sphere(0.5, world, transform=translate(0, 0.5001, 0.6), material=Copper())
Sphere(0.5, world, transform=translate(-0.6, 0.5001, -0.6), material=Titanium())
Sphere(0.5, world, transform=translate(-1.2, 0.5001, 0.6), material=Aluminium())
Sphere(0.5, world, transform=translate(0, 0.5001, -1.8), material=Beryllium())

Box(Point3D(-100, -0.1, -100), Point3D(100, 0, 100), world, material=Lambert(ConstantSF(1.0)))
Cylinder(3.0, 8.0, world, transform=translate(4, 8, 0) * rotate(90, 0, 0), material=UniformSurfaceEmitter(d65_white, 1.0))

camera = Node(parent=world, transform=translate(0, 4, -3.5) * rotate(0, -48, 180))

# b = BiConvex(0.0508, 0.0036, 1.0295, 1.0295, parent=camera, transform=translate(0, 0, 0.1), material=schott("N-BK7"))
# b = BiConvex(0.0508, 0.0062, 0.205, 0.205, parent=camera, transform=translate(0, 0, 0.05), material=schott("N-BK7"))
lens = BiConvex(0.0508, 0.0144, 0.0593, 0.0593, parent=camera, transform=translate(0, 0, 0.0536), material=schott("N-BK7"))

body = Subtract(
        Subtract(
            Cylinder(0.0260, 0.07, transform=translate(0, 0, 0)),
            Cylinder(0.0255, 0.06, transform=translate(0, 0, 0.005))
        ),
    Cylinder(0.015, 0.007, transform=translate(0, 0, 0.064)),
    parent=camera,
    transform=translate(0, 0, -0.01),
    material=AbsorbingSurface()
)

aperture = Cylinder(0.016, 0.0009, parent=camera, transform=translate(0, 0, 0.064), material=NullMaterial())

rgb = RGBPipeline2D(display_unsaturated_fraction=0.98, name="sRGB")
bayer = BayerPipeline2D(ciexyz_x, ciexyz_y, ciexyz_z, display_unsaturated_fraction=0.98, name="Bayer Filter")

sampler = RGBAdaptiveSampler2D(rgb, ratio=10, fraction=0.2, min_samples=500, cutoff=0.05)
pipelines = [rgb, bayer]

# ccd = CCDArray(parent=camera, pipelines=pipelines)
ccd = TargetedCCDArray(targets=[aperture], parent=camera, pipelines=pipelines)
ccd.frame_sampler = sampler
ccd.pixels = (180*2, 120*2)  # (360, 240)
ccd.pixel_samples = 250
ccd.spectral_rays = 1
ccd.spectral_bins = 15

# start ray tracing
ion()
p = 1
while not ccd.render_complete:
    print("Rendering pass {}...".format(p))
    ccd.observe()
    # ccd.pipelines[0].save("demo_metal_lens_{}.png".format(p))
    print()
    p += 1

ioff()
show()
```

--------------------------------

### MulticoreEngine Constructor

Source: http://www.raysect.org/api_reference/core/render_engines.html

Initializes a new MulticoreEngine instance to manage parallel rendering processes.

```APIDOC
## MulticoreEngine(processes=None, tasks_per_job=None, start_method='fork')

### Description
A render engine for distributing work across multiple CPU cores. It manages worker processes and task grouping to optimize rendering performance.

### Parameters
- **processes** (int/None) - Optional - The number of worker processes. Defaults to None, which uses all available CPU cores.
- **tasks_per_job** (int/None) - Optional - The number of tasks to group into a single job to reduce IPC overhead. Defaults to None for automatic adjustment.
- **start_method** (str) - Optional - The method used to start child processes: 'fork', 'spawn', or 'forkserver'. Defaults to 'fork'.

### Usage Example
```python
from raysect.core import MulticoreEngine
from raysect.optical.observer import PinholeCamera

camera = PinholeCamera((512, 512))

# Use all available CPU cores
camera.render_engine = MulticoreEngine()

# Force use of 8 CPU processes
camera.render_engine = MulticoreEngine(processes=8)
```
```

--------------------------------

### instance(parent=None, transform=None, material=None, name=None)

Source: http://www.raysect.org/api_reference/core/raysect_core_scenegraph.html

Creates a new instance of the primitive with the same geometry.

```APIDOC
## instance(parent=None, transform=None, material=None, name=None)

### Description
Returns a new instance of the primitive with the same geometry.

### Parameters
- **parent** (Node) - Optional - Assigns the Node’s parent to the specified scene-graph object.
- **transform** (AffineMatrix3D) - Optional - Sets the affine transform associated with the Node.
- **material** (Material) - Optional - An object representing the material properties of the primitive.
- **name** (str) - Optional - A string defining the node name.
```

--------------------------------

### Execute ray tracing render loop

Source: http://www.raysect.org/demonstrations/observers/cornell_box_with_camera.html

Runs the rendering process and saves output images periodically.

```python
# start ray tracing
ion()
p = 1
while not film.render_complete:

    print("Rendering pass {}...".format(p))

    film.observe()

    rgb.save('cornell_box_real_rgb_pass_{:04d}.png'.format(p))
    power_unfiltered.save('cornell_box_real_unfiltered_pass_{:04d}.png'.format(p))

    print()
    p += 1

ioff()
rgb.display()
```

--------------------------------

### Execute Rendering Loop

Source: http://www.raysect.org/demonstrations/observers/cornell_box.html

Runs the iterative rendering process and saves output images.

```python
# start ray tracing
ion()
name = 'cornell_box'
timestamp = time.strftime("%Y-%m-%d_%H-%M-%S")
render_pass = 1
while not camera.render_complete:

    print("Rendering pass {}...".format(render_pass))
    camera.observe()
    rgb.save("{}_{}_pass_{}.png".format(name, timestamp, render_pass))
    # power_unfiltered.save('cornell_box_unfiltered_pass_{:04d}.png'.format(p))
    # power_red.save('cornell_box_red_filter_pass_{:04d}.png'.format(p))
    # power_green.save('cornell_box_green_filter_pass_{:04d}.png'.format(p))
    # bayer.save('cornell_box_bayer_pass_{:04d}.png'.format(p))
    print()

    render_pass += 1

ioff()
rgb.display()
```