iFDO capture section

The iFDO capture is one section of the complete iFDO file. See its description to learn about its file formats, parts and sections. All fields in this section are optional!

Motivation

Information on how image data was captured can be crucial to understand information extracted from the images. It is thus highly recommended to enrich all iFDOs with capture information. The potential metadata in the iFDO capture fields is expected to grow with time, as additional (marine) imaging domains make use of this concept. Anyhow, below you find a pool of iFDO capture fields which are highly recommended to be added to your iFDO. Only with these fields populated will your dataset shine in a marine data portal! By limiting some of these fields to restricted values only, it is possible to classify and filter image data sets in data portals and to visualize data characteristics. See the iFDO capture icon overview for more details.

File format

All iFDO capture fields shall be stored alongside the core metadata in your iFDO file! It does not take up a specific section of the file, rather the values are intermixed into the image-set-header and image-set-items section!

iFDO capture fields

Field	Comment
image-acquisition	photo: still images, video: moving images, slide: microscopy images / slide scans
image-quality	raw: straight from the sensor, processed: QA/QC’d, product: image data ready for interpretation
image-deployment	mapping: planned path execution along 2-3 spatial axes, stationary: fixed spatial position, survey: planned path execution along free path, exploration: unplanned path execution, experiment: observation of manipulated environment, sampling: ex-situ imaging of samples taken by other method
image-navigation	satellite: GPS/Galileo etc., beacon: USBL etc., transponder: LBL etc., reconstructed: position estimated from other measures like cable length and course over ground
image-scale-reference	3D camera: the imaging system provides scale directly, calibrated camera: image data and additional external data like object distance provide scale together, laser marker: scale information is embedded in the visual data, optical flow: scale is computed from the relative movement of the images and the camera navigation data
image-illumination	sunlight: the scene is only illuminated by the sun, artificial light: the scene is only illuminated by artificial light, mixed light: both sunlight and artificial light illuminate the scene
image-pixel-magnitude	average size of one pixel of an image
image-marine-zone	seafloor: images taken in/on/right above the seafloor, water column: images taken in the free water without the seafloor or the sea surface in sight, sea surface: images taken right below the sea surface, atmosphere: images taken outside of the water, laboratory: images taken ex-situ
image-spectral-resolution	grayscale: single channel imagery, rgb: three channel imagery, multi-spectral: 4-10 channel imagery, hyper-spectral: 10+ channel imagery
image-capture-mode	whether the time points of image capture were systematic, human-truggered or both
image-fauna-attraction	Allowed values: none, baited, light
image-area-square-meter	The footprint of the entire image in square meters
image-meters-above-ground	Distance of the camera to the seafloor in meters
image-acquisition-settings	All the information that is recorded by the camera in the EXIF, IPTC etc. As a dict. Includes ISO, aperture, etc.
image-camera-yaw-degrees	Camera view yaw angle. Rotation of camera coordinates (x,y,z = top, right, line of sight) with respect to NED coordinates (x,y,z = north,east,down) in accordance with the yaw,pitch,roll rotation order convention: 1. yaw around z, 2. pitch around rotated y, 3. roll around rotated x. Rotation directions according to 'right-hand rule'. I.e. for yaw,pitch,roll = 0,0,0 camera is facing downward with top side towards north.
image-camera-pitch-degrees	Camera view pitch angle. Rotation of camera coordinates (x,y,z = top, right, line of sight) with respect to NED coordinates (x,y,z = north,east,down) in accordance with the yaw,pitch,roll rotation order convention: 1. yaw around z, 2. pitch around rotated y, 3. roll around rotated x. Rotation directions according to 'right-hand rule'. I.e. for yaw,pitch,roll = 0,0,0 camera is facing downward with top side towards north.
image-camera-roll-degrees	Camera view roll angle. Rotation of camera coordinates (x,y,z = top, right, line of sight) with respect to NED coordinates (x,y,z = north,east,down) in accordance with the yaw,pitch,roll rotation order convention: 1. yaw around z, 2. pitch around rotated y, 3. roll around rotated x. Rotation directions according to 'right-hand rule'. I.e. for yaw,pitch,roll = 0,0,0 camera is facing downward with top side towards north.
image-overlap-fraction	The average overlap of two consecutive images i and j as the area images in both of the images (A_i * A_j) divided by the total area images by the two images (A_i + A_j - A_i * A_j): f = A_i * A_j / (A_i + A_j - A_i * A_j) -> 0 if no overlap. 1 if complete overlap
image-datetime-format	A date time format string in Python notation (e.g. %Y-%m-%d %H:%M:%S.%f) to specify a different date format used throughout the iFDO file. The assumed default is the one in brackets. Make sure to reach second-accuracy with your date times!
image-camera-pose	Information required to specify camera pose. For details on subfields see rows below.
image-camera-pose:pose-utm-zone	The UTM zone number
image-camera-pose:pose-utm-epsg	The EPSG code of the UTM zone
image-camera-pose:pose-utm-east-north-up-meters	The position of the camera center in UTM coordinates.
image-camera-pose:pose-absolute-orientation-utm-matrix	3x3 row-major float rotation matrix that transforms a direction in camera coordinates (x,y,z = right,down,line of sight) into a direction in UTM coordinates (x,y,z = easting,northing,up)}
image-camera-housing-viewport	Information on the camera pressure housing viewport (the glass). For details on subfields see rows below.
image-camera-housing-viewport:viewport-type	e.g.: flatport, domeport, other
image-camera-housing-viewport:viewport-optical-density	Unit-less optical density number (1.0=vacuum)
image-camera-housing-viewport:viewport-thickness-millimeter	Thickness of viewport in millimeters
image-camera-housing-viewport:viewport-extra-description	A textual description of the viewport used
image-flatport-parameters	Information required to specify the characteristics of a flatport camera housing. For details on subfields see rows below.
image-flatport-parameters:flatport-lens-port-distance-millimeter	The distance between the front of the camera lens and the inner side of the housing viewport in millimeters.
image-flatport-parameters:flatport-interface-normal-direction	3D direction vector to specify how the view direction of the lens intersects with the viewport (unit-less, (0,0,1) is “aligned”)
image-flatport-parameters:flatport-extra-description	A textual description of the flatport used
image-domeport-parameters	Information required to specify the characteristics of a domeport camera housing. For details on subfields see rows below.
image-domeport-parameters:domeport-outer-radius-millimeter	Outer radius of the domeport - the part that has contact with the water.
image-domeport-parameters:domeport-decentering-offset-xyz-millimeter	3D offset vector of the camera center from the domeport center in millimeters
image-domeport-parameters:domeport-extra-description	A textual description of the domeport used
image-camera-calibration-model	Information required to specify the camera calibration model. For details on the subfields see rows below.
image-camera-calibration-model:calibration-model-type	e.g.: rectilinear air, rectilinear water, fisheye air, fisheye water, other
image-camera-calibration-model:calibration-focal-length-xy-pixel	2D focal length in pixels
image-camera-calibration-model:calibration-principal-point-xy-pixel	2D principal point of the calibration in pixels (top left pixel center is 0,0, x right, y down)
image-camera-calibration-model:calibration-distortion-coefficients	rectilinear: k1, k2, p1, p2, k3, k4, k5, k6, fisheye: k1, k2, k3, k4
image-camera-calibration-model:calibration-approximate-field-of-view-water-xy-degree	Proxy for pixel to meter conversion, and as backup
image-camera-calibration-model:calibration-model-extra-description	Explain model, or if lens parameters are in mm rather than in pixel
image-photometric-calibration	Information required to specify the photometric calibration. For details on the subfields see rows below.
image-photometric-calibration:photometric-sequence-white-balancing	A text on how white-balancing was done.
image-photometric-calibration:photometric-exposure-factor-RGB	RGB factors applied to this image, product of ISO, exposure time, relative white balance
image-photometric-calibration:photometric-sequence-illumination-type	e.g. “constant artificial”, “globally adapted artificial”, “individually varying light sources”, “sunlight”, “mixed”)
image-photometric-calibration:photometric-sequence-illumination-description	A text on how the image sequence was illuminated
image-photometric-calibration:photometric-illumination-factor-RGB	RGB factors applied to artificial lights for this image
image-photometric-calibration:photometric-water-properties-description	A text describing the photometric properties of the water within which the images were capture
image-objective	A general translation of the aims and objectives of the study, as they pertain to biology and method scope. This should define the primary and secondary data to be measured and to what precision.
image-target-environment	A description, delineation, and definition of the habitat or environment of study, including boundaries of such
image-target-timescale	A description, delineation, and definition of the period, interval or temporal environment of the study.
image-spatial-constraints	A description / definition of the spatial extent of the study area (inside which the photographs were captured), including boundaries and reasons for constraints (e.g. scientific, practical)
image-temporal-constraints	A description / definition of the temporal extent, including boundaries and reasons for constraints (e.g. scientific, practical)
image-time-synchronisation	Synchronisation procedure and determined time offsets between camera recording values and UTC
image-item-identification-scheme	How the images file names are constructed. Should be like this <project>_<event>_<sensor>_<date>_<time>.<ext>
image-curation-protocol	A description of the image and metadata curation steps and results