Cameras and lenses

Generated from the schema registry by ernie schema --markdown.

Camera

A view looking down -z, y up, with a lens and film.

Prim type · Inherits Xformable

Attribute	Type	Description	Fallback	Values	Source
`projection`	token	How it projects the scene.	`"perspective"`	`perspective`, `orthographic`	UsdGeom
`horizontalAperture`	double	Film width, metres.	`0.020955`	≥ 0	UsdGeom
`verticalAperture`	double	Film height, metres.	`0.0152908`	≥ 0	UsdGeom
`horizontalApertureOffset`	double	The film's offset from the lens axis along x, metres.	`0.0`		UsdGeom
`verticalApertureOffset`	double	The film's offset from the lens axis along y, metres.	`0.0`		UsdGeom
`focalLength`	double	The lens's focal length, metres.	`0.05`	≥ 0	UsdGeom
`clippingRange`	double2	Near and far distances in metres.	`[1.0,1000000.0]`	> 0	UsdGeom
`clippingPlanes`	float[n, 4]	(n, 4) planes (a, b, c, d) keeping points where a x + b y + c z + d >= 0.			UsdGeom
`fStop`	double	The lens's f-number; 0 for a pinhole, all in focus.	`0.0`	≥ 0	UsdGeom
`focusDistance`	double	Metres to the plane in focus.	`0.0`	≥ 0	UsdGeom
`stereoRole`	token	Which eye it is.	`"mono"`	`mono`, `left`, `right`	UsdGeom
`shutter:open`	double	Frames from the time code the shutter opens.	`0.0`		UsdGeom
`shutter:close`	double	Frames from the time code it closes.	`0.0`		UsdGeom
`exposure`	double	Stops of exposure added to the image.	`0.0`		UsdGeom
`exposure:iso`	double	The sensor's ISO speed.	`100.0`	> 0	UsdGeom
`exposure:time`	double	Seconds of exposure.	`1.0`	≥ 0	UsdGeom
`exposure:fStop`	double	The f-number exposure is computed with.	`1.0`	> 0	UsdGeom
`exposure:responsivity`	double	The sensor's responsivity.	`1.0`	≥ 0	UsdGeom
`ernie:exposure:mode`	token	auto keys the image to middle grey from the metered scene, after the settings above.	`"manual"`	`manual`, `auto`	Ernie
`ernie:exposure:adaptation`	double	Frames auto exposure takes to cover 63% of a change; 0 at once.	`0.0`	≥ 0	Ernie
`ernie:shutter:samples`	int	Sub-frames rendered across the shutter.	`8`	≥ 1	Ernie
`ernie:shutter:rolling`	double	Frames between the top row's exposure and the bottom row's; 0 global.	`0.0`	≥ 0	Ernie
`ernie:camera:scan`	token	pushbroom: a line scanner whose rows run from the last frame's pose to this one's.	`"frame"`	`frame`, `pushbroom`	Ernie
`ernie:pushbroom:lineOffset`	double	Metres from the principal point to the pushbroom's detector line.	`0.0`		Ernie

{
  "$schema": "https://alexmaietta.github.io/ernie/schema/ernie-scene.schema.json",
  "prims": {
    "/World/Camera": {
      "typeName": "Camera",
      "projection": "perspective",
      "horizontalAperture": 0.020955,
      "verticalAperture": 0.0152908,
      "horizontalApertureOffset": 0.0,
      "verticalApertureOffset": 0.0,
      "focalLength": 0.05,
      "clippingRange": [1.0, 1000000.0],
      "fStop": 0.0,
      "focusDistance": 0.0,
      "stereoRole": "mono",
      "shutter:open": 0.0,
      "shutter:close": 0.0,
      "exposure": 0.0,
      "exposure:iso": 100.0,
      "exposure:time": 1.0,
      "exposure:fStop": 1.0,
      "exposure:responsivity": 1.0,
      "ernie:exposure:mode": "manual",
      "ernie:exposure:adaptation": 0.0,
      "ernie:shutter:samples": 8,
      "ernie:shutter:rolling": 0.0,
      "ernie:camera:scan": "frame",
      "ernie:pushbroom:lineOffset": 0.0
    }
  }
}

ErnieLensAPI

A camera's lens beyond USD's: fisheyes, distortion, vignetting and chromatic aberration.

API schema

Attribute	Type	Description	Fallback	Values	Source
`ernie:lens:projection`	token	Rectilinear, or a Kannala-Brandt fisheye.	`"perspective"`	`perspective`, `fisheye`	Ernie
`ernie:lens:distortion`	float[]	Brown-Conrady k1 k2 k3 p1 p2; missing ones are 0.	`[]`		Ernie
`ernie:lens:fisheye`	float[]	Kannala-Brandt k1 k2 k3 k4 of a fisheye; none is equidistant.	`[]`		Ernie
`ernie:lens:vignetting`	bool	Natural falloff off axis.	`false`		Ernie
`ernie:lens:transmission`	double	The fraction of light passed.	`1.0`	≥ 0, ≤ 1	Ernie
`ernie:lens:chromatic:scale`	float[]	(nm, scale) pairs: lateral colour, the image's scale per wavelength.	`[]`		Ernie
`ernie:lens:chromatic:focus`	float[]	(nm, metres) pairs: axial colour, the focal length's shift per wavelength.	`[]`		Ernie
`ernie:lens:rays`	float tensor, rank 3	float32 (rows, columns, 3) unit directions every rays step pixels, in place of the projection and distortion.			Ernie
`ernie:lens:raysStep`	int	Pixels between the lens's rays.	`8`	≥ 1	Ernie

{
  "$schema": "https://alexmaietta.github.io/ernie/schema/ernie-scene.schema.json",
  "prims": {
    "/World/ErnieLensAPI": {
      "typeName": "Xform",
      "apiSchemas": ["ErnieLensAPI"],
      "ernie:lens:projection": "perspective",
      "ernie:lens:distortion": [],
      "ernie:lens:fisheye": [],
      "ernie:lens:vignetting": false,
      "ernie:lens:transmission": 1.0,
      "ernie:lens:chromatic:scale": [],
      "ernie:lens:chromatic:focus": [],
      "ernie:lens:raysStep": 8
    }
  }
}

ErniePolarizerAPI

A polarizer in front of a camera's lens, or a polarization sensor's mosaic.

API schema

Attribute	Type	Description	Fallback	Values	Source
`ernie:polarizer:type`	token	linear in front of the lens, or a mosaic of 90, 45 / 135, 0 degree polarizers over 2 x 2 pixels, as a polarization sensor's.	`"linear"`	`linear`, `mosaic`	Ernie
`ernie:polarizer:angle`	double	Degrees from the image's +x towards +y to a linear polarizer's axis.	`0.0`		Ernie
`ernie:polarizer:extinction`	double	Light passed along the axis over light passed across it.	`1000.0`	≥ 1	Ernie
`ernie:polarizer:transmission`	double	The fraction of light polarized along the axis passed.	`0.85`	≥ 0, ≤ 1	Ernie

{
  "$schema": "https://alexmaietta.github.io/ernie/schema/ernie-scene.schema.json",
  "prims": {
    "/World/ErniePolarizerAPI": {
      "typeName": "Xform",
      "apiSchemas": ["ErniePolarizerAPI"],
      "ernie:polarizer:type": "linear",
      "ernie:polarizer:angle": 0.0,
      "ernie:polarizer:extinction": 1000.0,
      "ernie:polarizer:transmission": 0.85
    }
  }
}

ErnieSensorAPI

A camera's sensor: its spectral range, noise, ADC and quantum efficiency; its products set how finely the range is sampled.

API schema

Attribute	Type	Description	Fallback	Values	Source
`ernie:spectral:range`	double2	Wavelengths in nm the sensor responds to; its products sample them in bands.	`[380.0,780.0]`	> 0	Ernie
`ernie:sensor:type`	token	A colour or a mono sensor.	`"rgb"`	`rgb`, `mono`	Ernie
`ernie:sensor:noise`	bool	Whether it adds the noise below.	`true`		Ernie
`ernie:sensor:fullWell`	double	Electrons a pixel holds.	`20000.0`	> 0	Ernie
`ernie:sensor:readNoise`	double	Electrons, standard deviation.	`3.0`	≥ 0	Ernie
`ernie:sensor:darkCurrent`	double	Electrons per second.	`0.1`	≥ 0	Ernie
`ernie:sensor:prnu`	double	Standard deviation of each pixel's relative gain.	`0.005`	≥ 0	Ernie
`ernie:sensor:dsnu`	double	Electrons, standard deviation of each pixel's offset.	`0.5`	≥ 0	Ernie
`ernie:sensor:electronsPerDn`	double	At ISO 100; 0 for the full well over the bit depth's range.	`0.0`	≥ 0	Ernie
`ernie:sensor:bitDepth`	int	Bits of each digital number the sensor's ADC makes, such as 8, 12 or 16.	`12`	≥ 1, ≤ 32	Ernie
`ernie:sensor:blackLevel`	double	DN added to every pixel.	`0.0`	≥ 0	Ernie
`ernie:sensor:pixelPitch`	double	Micrometres, of orthographic cameras.	`5.0`	> 0	Ernie
`ernie:sensor:seed`	int	The seed of the sensor's noise.	`0`		Ernie
`ernie:sensor:qe:r`	float[]	(nm, electrons per photon) pairs of the red channel; unset keeps the generic curve.	`[]`		Ernie
`ernie:sensor:qe:g`	float[]	(nm, electrons per photon) pairs of the green channel; unset keeps the generic curve.	`[]`		Ernie
`ernie:sensor:qe:b`	float[]	(nm, electrons per photon) pairs of the blue channel; unset keeps the generic curve.	`[]`		Ernie
`ernie:sensor:qe:mono`	float[]	(nm, electrons per photon) pairs of the mono channel; unset keeps the generic curve.	`[]`		Ernie

{
  "$schema": "https://alexmaietta.github.io/ernie/schema/ernie-scene.schema.json",
  "prims": {
    "/World/ErnieSensorAPI": {
      "typeName": "Xform",
      "apiSchemas": ["ErnieSensorAPI"],
      "ernie:spectral:range": [380.0, 780.0],
      "ernie:sensor:type": "rgb",
      "ernie:sensor:noise": true,
      "ernie:sensor:fullWell": 20000.0,
      "ernie:sensor:readNoise": 3.0,
      "ernie:sensor:darkCurrent": 0.1,
      "ernie:sensor:prnu": 0.005,
      "ernie:sensor:dsnu": 0.5,
      "ernie:sensor:electronsPerDn": 0.0,
      "ernie:sensor:bitDepth": 12,
      "ernie:sensor:blackLevel": 0.0,
      "ernie:sensor:pixelPitch": 5.0,
      "ernie:sensor:seed": 0,
      "ernie:sensor:qe:r": [],
      "ernie:sensor:qe:g": [],
      "ernie:sensor:qe:b": [],
      "ernie:sensor:qe:mono": []
    }
  }
}