Pix4D Desktop reads information from the image EXIF data. It reads both standard EXIF tags and Pix4D defined camera XMP tags.
IN THIS ARTICLE
(EXIF) Standard tags
(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
Some tags are required in order to be compatible with Pix4D Desktop:
- All projects
- Exif.Image.Make
- Exif.Image.Model
- Exif.Photo.FocalLength
- Exif.Photo.DateTimeOriginal
- 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: 115001846106.
(EXIF) Standard tags
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Exif.Image.Make | Canon | String | The camera manufacturer name |
| Exif.Image.Model | Canon EOS REBEL SL1 | String | The model name of the camera |
| Exif.Image.BlackLevelRepeatDim | 2 2 | Short | Dimension of dark current matrix |
| Exif.Image.BlackLevel | 320 198 275 201 | Short | Dark current, matrix of dimension given in Exif.Image.BlackLevelRepeatDim in row major |
| Exif.Photo.BodySerialNumber | 092172012311 | String | The serial number of the camera |
| Exif.Photo.FocalLength | 20/1 | Rational | Focal length [mm] Note: If Exif.Photo.FocalLength is not found, Exif.Photo.FocalLengthIn35mmFilm is used to calculate the focal length |
| Exif.Photo.DateTimeOriginal | 2011:02:10 14:11:27 | String | Date and time of image acquisition in the format yyyy:mm:dd HH:MM:SS |
| Exif.Photo.SubSecTimeOriginal | 27 | Short | Time of image acquisition: sub-second part |
| Exif.Photo.FocalPlaneXResolution | 5184000/894 | Rational | Pixels per unit, used for sensor and pixel size |
| Exif.Photo.FocalPlaneYResolution | 3456000/597 | Rational | Pixels per unit, used for sensor and pixel size Note: if FocalPlaneXResolution / FocalPlaneYResolution are not found, FocalLength and FocalLengthIn35mmFilm are used to calculate the sensor/pixel size |
| Exif.Photo.FocalPlaneResolutionUnit | 4 | Short | Unit for Exif.Photo.FocalPlane[XY]Resolution: 2 = inch 3 = cm 4 = mm |
| Exif.Photo.ExposureTime | 1/1000 | Rational | Exposure time [seconds] |
| Exif.Photo.FNumber | 28/10 | Rational | Aperture F number |
| Exif.CanonSi.ApertureValue | binary | For Canon cameras, this non-standard tag takes precedence over Exif.Photo.FNumber since it contains some effective value for the f number. Note that the number has a special binary format. | |
| Exif.Photo.ISOSpeedRatings | 400 | Short | ISO film speed of the camera Note: If Exif.Photo.ISOSpeedRatings is not found, Exif.Photo.ISOSpeed is used |
| Exif.Photo.LensModel | EF40mm f/2.8 STM | String | Describes the lens (can be empty) |
| Exif.Photo.LensSerialNumber | 1055005868 | String | The serial number of the lens |
| Exif.GPSInfo.GPSLatitude | 46/1 22059917/1000000 | List of Rational | GPS degree and/or minute and/or second. In some formats the list of rationals is shorter and the seconds and/or minutes part are ignored. |
| Exif.GPSInfo.GPSLatitudeRef | N or S | String | GPS reference north or south |
| Exif.GPSInfo.GPSLongitude | 46/1 25642511/1000000 | List of Rational | GPS degree and/or minute and/or second. In some formats the list of rationals is shorter and the seconds and/or minutes part are ignored. |
| Exif.GPSInfo.GPSLongitudeRef | E or W | String | GPS reference east or west |
| Exif.GPSInfo.GPSAltitude | 1205/100 | Rational | Mean Sea Level altitude (GPS altitude) |
| Exif.GPSInfo.GPSAltitudeRef | 0 | Short | GPS altitude reference: 0 > sea level |
| Exif.GPSInfo.GPSMapDatum | WGS-84 | String | GPS coordinate system |
| Exif.GPSInfo.GPSDateStamp | 2016:03:01 | Ascii | GPS date (UTC) |
| Exif.GPSInfo.GPSTimeStamp | 12/1 8/1 54785/1000 | List of Rational |
GPS time as hour, minute, second (UTC), with sub-second accuracy
|
| Exif.Image.SubjectDistance | 12.87 | Double | Distance from camera to subject [meters] (e.g. ultrasound-based measure) |
(XMP) Camera
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Xmp.Camera.ModelType | "fisheye" | Ascii | Camera model type: one of "perspective" or "fisheye". |
| Xmp.Camera.PrincipalPoint | 2.42299,1.850154 | Ascii | cx, cy in millimetres separated by comma. |
| Xmp.Camera.PerspectiveFocalLength | 4.569165 | double | For perspective camera: focal length in millimetres. |
| Xmp.Camera.PerspectiveDistortion |
0.201690322,-0.358534038, 0.256185599, 0.004208643,0.000268361 |
Ascii | For perspective camera: R1, R2, R3, T1, T2 separated by comma: 202559089. |
| Xmp.Camera.FisheyeAffineMatrix |
1583.319083002,0,0, 1583.319083002 |
Ascii | For fisheye camera: Affine matrix C, D, E, F separated by comma: 202559089. |
| 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: 202559089. |
| 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: 202558969. |
(XMP) Radiometric correction
| Key | Value example | Type | Meaning |
|---|---|---|---|
| Xmp.Camera.BandName | {"Red", "NIR"} | XmpSeq | Name of each band (sequence). Single page image: one name for each band of the image. Multipage image: one band name per image page. (Note: this allows only one band per page, since sequence of sequence is not possible). |
| 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: 115001846106. |
| 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): 115001846106. |
| 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): 115001846106. |
| 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): 115001846106. |
| 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): 115001846106. |
| 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 | Bool | Defines whether 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: 205675256. |
| Xmp.Camera.Pitch | 1.7943 | Rational or Double | Orientation data in degrees. For more information on the definition of yaw, pitch, roll: 205675256. |
| Xmp.Camera.Roll | 2.8909 | Rational or Double | Orientation data in degrees. For more information on the definition of yaw, pitch, roll: 205675256. |
| 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.IMUAngularVelocity | XmpString | Base64 encoded array of floats (gyrX gyrY gyrZ) for each sample in radian/s. The x, y and z axes are the standard image axes: centered on the upper left corner, x is horizontal (going right), y is vertical (going down), z is going towards the scene (inside the image). Angles are in counter-clockwise direction. The order of the rotations is: rotX, rotY, rotZ. | |
| Xmp.Camera.IMUFrequency | Double | The sample frequency of Xmp.Camera.IMUAngularVelocity in Hz. | |
| Xmp.Camera.IMUTimeOffset | Double | The time offset between the first IMU sample and the beginning of the image readout in nanoseconds. | |
| Xmp.Camera.IMULinearVelocity | XmpString | 3-vector separated by comma (v_x, v_y, v_z) representing the linear velocity in m/s. The x, y and z axes are the standard image axes: centered on the upper left corner, x is horizontal (going right), y is vertical (going down), z is going towards the scene (inside the image). | |
| 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 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: 205675256. |
|
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: 205675256. |
| 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: 205675256. |
| 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 Celsius]. |
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