(XMP) Camera
(XMP) Radiometric correction
(XMP) Radiometric calibration target
(XMP) Position and orientation
(XMP) Sun irradiance position and orientation
(XMP) Bit-depth reduction
(XMP) Miscellaneous
Projects which require radiometric calculations (e.g. agriculture applications): Refer to the camera XMP section as well as this page which gives the specifications for the different corrections to be applied: Exif/Xmp tags for radiometric correction.
(XMP) Camera
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Xmp.Camera.ModelType | "fisheye" | XmpText | Camera model type: one of "perspective" or "fisheye". |
| Xmp.Camera.PrincipalPoint | 2.42299,1.850154 | XmpText | cx, cy in millimetres separated by comma. |
| Xmp.Camera.PerspectiveFocalLength | 4.569165 | XmpText | For perspective camera: focal length in millimetres. |
| Xmp.Camera.PerspectiveDistortion |
0.201690322,-0.358534038, 0.256185599, 0.004208643,0.000268361 |
XmpText | For perspective camera: R1, R2, R3, T1, T2 separated by comma: How are the Internal and External Camera Parameters defined?. |
| Xmp.Camera.FisheyeAffineMatrix |
1583.319083002,0,0, 1583.319083002 |
Ascii | For fisheye camera: Affine matrix C, D, E, F separated by comma: How are the Internal and External Camera Parameters defined?. |
| Xmp.Camera.FisheyeAffineSymmetric | 1 | Boolean | For fisheye camera: If symmetric affine matrix should be used (default false). |
| Xmp.Camera.FisheyePolynomial |
0,1,-0.025178575, 0.167834214 |
Ascii | For fisheye camera: Polynomial separated by comma: How are the Internal and External Camera Parameters defined?. |
| Xmp.Camera.RigName | Airinov multiSPEC4C 1.1 | XmpText | Name of the rig model this image belongs to. |
| Xmp.Camera.RigCameraIndex | 0 | Short | Corresponding camera index within the rig model. |
| Xmp.Camera.RigRelatives | 0.3836, -1.27665, -0.1156 | XmpText | Rotation angles with respect to the reference camera. For angle convention in Pix4D: Yaw, Pitch, Roll and Omega, Phi, Kappa angles . |
| Xmp..Camera. |
mm | XmpText | The unit of the focal length |
| Xmp.Camera.CaptureUUID | B9A2F3676304A83F92261B5245124F28 | XmpText | Unique identifier for one capture within a flight. This allows to find that capture across different rig cameras. |
| Xmp.Camera.FlightUUID | 7F8DC95FFCADA339805BD53338EC888E | XmpText | Unique identifier for one flight |
(XMP) Radiometric correction
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Xmp.Camera.BandName | {"Red", "NIR"} | XmpSeq |
Name of each band (sequence). The band name must not start with the following characters: 0-9, ',', '(' or ')'. |
| Xmp.Camera.CentralWavelength | {660, 800} | XmpSeq | Central wavelength of each band in nm. Similar to band names. If band names are not defined, default band names are generated. |
| Xmp.Camera.WavelengthFWHM | {10, 10} | XmpSeq | Full-width half maximum of the wavelength distribution in nm. |
| Xmp.Camera.BlackCurrent |
{10, 7} |
XmpSeq | Dark current for each band/page: Camera radiometric correction specifications. |
| Xmp.Camera.BandSensitivity | {0.78, 0.043} | XmpSeq | The sensitivity of each band (pixel intensity value per irradiance). |
| Xmp.Camera.SunSensor | {12.87, 9.72} | XmpSeq | Sun irradiance sensor (upwards looking sensor) raw value for each band. |
| Xmp.Camera.SunSensorExposureTime | {0.1, 0.1} | XmpSeq | Sun irradiance sensor exposure time in seconds. |
| Xmp.Camera.SunSensorSensitivity | {16.45, 14.08} | XmpSeq | Sun irradiance sensor sensitivity. |
| Xmp.Camera.InvalidPixel | {"40,593,981,291"} | XmpSeq | List of bad pixels as comma-separated x,y coordinate list, one sequence for each band. |
| Xmp.Camera.VignettingPolynomial | {"0.00325, 1.983e-6, 5.0983e-9"} | XmpSeq | Vignetting correction by radial polynomial: 1D polynomial coefficients (one string of comma-separated values per page, 1 string for RGB images): Camera radiometric correction specifications. |
| Xmp.Camera.VignettingCenter | {"542,912"} | XmpSeq | Vignetting correction by radial polynomial: Center point cx, cy in pixel (one string of comma-separated values per page): Camera radiometric correction specifications. |
| Xmp.Camera.VignettingPolynomial2DName | {"0,0,1,0, ..., 2,2,3,1"} | XmpSeq | Vignetting correction by 2D polynomial: name of coefficients: n,m for c_{n,m} separated by commas (one string of comma-separated values per page): Camera radiometric correction specifications. |
| Xmp.Camera.VignettingPolynomial2D | {"0.633287676149, 1.47936368033, ..., -1.58329242609, 0.130259802058"} | XmpSeq | Vignetting correction by 2D polynomial: coefficients c_{n,m} for names given by Xmp.Camera.VignettingPolynomial2DName separated by commas (one string of comma-separated values per page): Camera radiometric correction specifications. |
| Xmp.Camera.ColorTransform |
{1, -0.114886,-0.0456918, -0.176716, 1, 0, -0.0715561, 0, 1} |
XmpSeq | Sequence of double, color conversion matrix (for RGB: R2R, G2R, B2R, R2G, G2G, B2G, R2B, G2B, B2B). Considering the information as a 3x3 matrix M, (R,G,B)<sub>new</sub>= M * (R,G,B). |
| Xmp.Camera.IsNormalized | 1 | Boolean | Defines whether the radiometric correction is required (value 0) or the data has already been corrected (value 1) and therefore should not be corrected. |
(XMP) Radiometric calibration target
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Xmp.Camera.Albedo | {0.22, 0.19 , 0.37} | XmpSeq | For radiometric calibration target images: Albedo of the disk for each band/page. |
| Xmp.Camera.ReflectArea | {"X1,Y1,X2,Y2,X3,Y3,X4,Y4", "X1,Y1,...", ...} | XmpSeq | For radiometric calibration target images: polygon defining the target area for each page. |
| Xmp.Camera.CalibrationPicture | 2 | Short |
Specifies if this image is a radiometric calibration target: 0 = no, 1 = yes but invalid, 2 = yes and valid. For Sequoia cameras: 0 = no, 1 and 2 = yes. |
(XMP) Position and orientation
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Xmp.Camera.Yaw | 72.7942 | Rational or Double | Orientation data in degrees. For more information on the definition of yaw, pitch, roll: Yaw, Pitch, Roll and Omega, Phi, Kappa angles. |
| Xmp.Camera.Pitch | 1.7943 | Rational or Double | Orientation data in degrees. For more information on the definition of yaw, pitch, roll: Yaw, Pitch, Roll and Omega, Phi, Kappa angles. |
| Xmp.Camera.Roll | 2.8909 | Rational or Double | Orientation data in degrees. For more information on the definition of yaw, pitch, roll: Yaw, Pitch, Roll and Omega, Phi, Kappa angles. |
| Xmp.Camera.GPSXYAccuracy | 5 | Rational | Horizontal GPS Accuracy in meters. |
| Xmp.Camera.GPSZAccuracy | 10 | Rational | Vertical GPS Accuracy in meters. |
| Xmp.Camera.GyroRate | 0.0487 | Rational | Gyro rate during image acquisition, lower = better quality. |
| Xmp.Camera.IMUPitchAccuracy | 0.113 | Rational | The value in degrees of 1-sigma of the Gaussian noise of the IMU Pitch measurement. |
| Xmp.Camera.IMURollAccuracy | 0.087 | Rational | The value in degrees of 1-sigma of the Gaussian noise of the IMU Roll measurement. |
| Xmp.Camera.IMUYawAccuracy | 1.250 | Rational | The value in degrees of 1-sigma of the Gaussian noise of the IMU Yaw measurement. |
| Xmp.Camera.NominalCameraDistance | 25.87 | Rational | Nominal GPS distance between calibrated cameras in meters in order to have a decent overlap. Use to dynamically remove the cameras with worst quality as determined by the GyroRate such the target distance is as specified. |
| Xmp.Camera.AboveGroundAltitude | 25.3 | Rational or Double | Altitude above ground/take-off location in meters (from the altimeter of the drone). |
(XMP) Sun irradiance position and orientation
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Xmp.Camera.SunSensorYaw | 72.7942 | Rational or Double | Sun irradiance sensor orientation data in degrees. For more information on the definition of yaw, pitch, roll: Yaw, Pitch, Roll and Omega, Phi, Kappa angles. |
|
Xmp.Camera.SunSensorPitch |
1.7943 | Rational or Double | Sun irradiance sensor orientation data in degrees. For more information on the definition of yaw, pitch, roll: Yaw, Pitch, Roll and Omega, Phi, Kappa angles. |
| Xmp.Camera.SunSensorRoll | 2.8909 | Rational or Double | Sun irradiance sensor orientation data in degrees. For more information on the definition of yaw, pitch, roll: Yaw, Pitch, Roll and Omega, Phi, Kappa angles. |
| Xmp.Camera.SunSensorRelativeRotation | 175, 0, 0 | XmpSeq | Relative angle between camera and sunshine sensor in the omega, phi, kappa system (same as rig relatives). |
(XMP) Bit-depth reduction
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Xmp.Camera.TransformAlpha | {55684.1, 58672.8, 58889.1} | XmpSeq |
Sequence of double, alpha parameter for each band. where pixel_normalized is the pixel value stored in the JPG image scaled to the [0,1] interval. |
| Xmp.Camera.TransformBeta | {9850.9, 6862.2, 6645.91} | XmpSeq | Sequence of double, beta parameter for each band. |
| Xmp.Camera.TransformGamma | {2.12109, 2.6243, 2.33549} | XmpSeq | Sequence of double, gamma parameter for each band. |
(XMP) Miscellaneous
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Xmp.Camera.SensorBitDepth | 14 | Short | Bit depth of the original sensor |
| Xmp.Camera.SensorTemperature | 43.4 | Double | Temperature of the sensor (degree Celcius) |
Technical details about the format are lacking somewhat. Where are the definitions for the data types that you mention? ie. By "Rational", do you mean a text string with a rational value expressed as the ratio of two integers (like "345/100" for example)? -- this is the way XMP Exif Rational values are stored. And what is a "Double" -- do you allow exponential notation, and if so what is the format, and is the range limited to that of an IEEE 8-byte double? Also, how is "ASCII" different from "XMPText"? How is Short different from a regular integer (is it limited to < 65536)? And for XmpSeq, you should say "Seq of Double" or something similar -- sometimes the type isn't specified. In general, it would be much clearer if you used the same terminology as the XMP specification, and referred to that specification for the details. And an XMP Boolean is typically a string which is either "True" or "False", but you seem to be using an integer for this (with values of "0" and "1"?). And one more thing: What is the namespace URI and preferred namespace prefix? -- these must be defined somewhere but I can't find them.
Hi Phil, Pix4D uses exiv2 to read the EXIF/XMP tags. You can have a look at their website for the data types (https://www.exiv2.org/sample.html)