Each time you take a photo, you capture information that is referred to as metadata. This data is extremely useful when creating 3D reconstructions.

Metadata is stored in two types of files:

  • EXIF (Exchangeable Image File): contains information about the specific camera settings used when capturing a specific image. This information includes details such as GPS position, camera make and model, date and time, shutter speed, focal length and more.
  • XMP (Extensible Metadata Platform): the data standard for Adobe’s Extensible Metadata Platform

The information included in metadata files consists of camera intrinsics and camera extrinsics.

  • Camera intrinsics refers to the focal length and optical center of the camera
  • Camera extrinsics refers to the camera’s physical location and the direction it is pointing.

Using the extrinsic parameters, we can create camera coordinates which are mapped into the image plane using the intrinsics parameters.

[accordion heading="Skydio X10 camera information"]

Photo Camera Intrinsics

Below are example values from EXIF/XMP data relevant to camera intrinsics. The values are from our “prototype” calibrations which should be very close for a drone of that type. Image files from a specific drone will have factory-calibrated values that will be even more accurate.

Skydio X10 VT300-Z and VT300-L Narrow Camera

 

Resolution: Full (64MP)

Resolution: 1/4 (16MP)

Calibrated Focal Length X

12668.3474

6334.1737

Calibrated Focal Length Y

12611.0291

6305.51455

Calibrated Optical Center X

4623.5

2311.5
Calibrated Optical Center Y 3471.5 1735.5
Dewarp Data 0.29974, -2.41630, 4.52709 0.29974, -2.41630, 4.52709
Image Width 9248 4624
Image Height 6944 3472
Focal Length 9.88 mm 9.88 mm
Focal Length in 35mm Format 46 mm 46 mm
Pixel Size 0.8 μm 1.6 μm
Minimum Focus Distance 1 m 1 m
Horizontal Field of View 40° 40°
Vertical Field of View 30° 30°
Diagonal Field of View 50° 50°
Resolution 9248 x 6944 (64 MP) 4624 x 3472 (16MP)

Skydio X10 VT300-Z Telephoto Camera

 

Resolution: Full (48MP)

Resolution: 1/4 (12MP)

Calibrated Focal Length X

43741.25

21870.625

Calibrated Focal Length Y 43724.5833 21862.29165
Calibrated Optical Center X 3999.5 1999.5
Calibrated Optical Center Y 2999.5 1499.5
Dewarp Data 0,0,0 0,0,0
Image Width 8000 4000
Image Height 6000 3000
Focal Length 35 mm 35 mm
Focal Length in 35mm Format 190 mm 190 mm
Pixel Size 0.8 μm 1.6 μm
Minimum Focus Distance 5 m 5 m
Horizontal Field of View 10° 10°
Vertical Field of View
Diagonal Field of View 13° 13°
Resolution 8000 x 6000 (48 MP) 4000 x 3000 (12MP)

Skydio X10 VT300-Z and VT300-L Thermal Camera

Calibrated Focal Length X

1135.47

Calibrated Focal Length Y 1141.15
Calibrated Optical Center X 319.5
Calibrated Optical Center Y 255.5
Dewarp Data 0,0,0
Image Width 640
Image Height 512
Focal Length 13.6 mm
Focal Length in 35mm Format 60 mm
Pixel Size 12 μm
Minimum Focus Distance 5 m
Horizontal Field of View 32°
Vertical Field of View 25°
Diagonal Field of View 41°
Resolution 640 x 512 (0.3 MP)
[note] Read How to use Thermal Tools with Skydio X10 for more information. [/note]

Skydio X10 VT300-L Wide Camera

 

Resolution: Full (50MP)

Resolution: 1/4 (12MP)

Calibrated Focal Length X

4938.5577 2469.27885
Calibrated Focal Length Y 4936.49213 2468.24606
Calibrated Optical Center X 4095.5 2047.5
Calibrated Optical Center Y 3071.5 1535.5
Dewarp Data 0.00212, 0.04709, -0.05137 0.00212, 0.04709, -0.05137
Image Width 8192 4096
Image Height 6144 3072
Focal Length 7.74 mm 7.74 mm
Focal Length in 35mm Format 20 mm 20 mm
Pixel Size 1.6 μm 3.2 μm
Minimum Focus Distance 1 m 1 m
Horizontal Field of View 80° 80°
Vertical Field of View 65° 65°
Diagonal Field of View 93° 93°
Resolution 8192 x 6144 (50.3 MP) 4096 x 3072 (12.5 MP)

 

Computing pixel from point

The model we use is a simplification of the standard OpenCV model with the denominator coefficients and tangential coefficients omitted. This is a similar to the model from A Flexible New Technique for Camera Calibration, 1998

Below is an example of how to compute the projection of a point from an example calibration in Python:

Screen

[/accordion]

[accordion heading="EXIF/XMP Tag Descriptions"]

To access EXIF or XMP data, use a metadata reader tool such as https://exif.tools/

Coordinate Conventions

GPS

Latitude and longitude are in WGS84 coordinates

  • Altitude is geoid (or orthometric)
  • Height/altitude (roughly equivalent to height above mean sea level) in EGM96 computed by interpolation from a 10 deg x 10 deg grid
FLU

Front left up coordinates

NED

North East Down local cartesian coordinates relative to an arbitrary GPS linearization point

Yaw north is zero, yaw east is 90 degrees

Reference frames

Visual Frame

From our visual system, relative to where the drone turned on

World Frame

GPS based reference frame, linearized about an arbitrary point near where the drone is turned on

Hybrid Frame

From our visual system, transformed into the world frame

Standard EXIF GPS Field

 

GPSVersionID
GPSProcessingMethod
GPSLatitude
GPSLongitude
GPSAltitude
GPSAltitudeRef
GPSTimeStamp
GPSSatellites
GPSHPositioningError
GPSImgDirection
GPSImgDirectionRef
GPSSpeed
GPSSpeedRef
GPSTrack
GPSTrackRef

Images captured in Skills and 3D Scan

Make

Skydio

Model

Skydio X10 VT300-Z

  • VT300-Z_50 (Narrow)
  • VT300-Z_13 (Telephoto)
  • VT300-Z_40 (Thermal)

Skydio X10 VT300-L

  • VT300-L_93 (Wide)
  • VT300-L_50 (Narrow)
  • VT300-L_40 (Thermal)

VehicleID

Unique vehicle ID

VehicleName

Drone name

  • Skydio X10 VehicleName is displayed as SkydioX10-1234

ReleaseKey

Software release key

FlightId

Unique flight ID

LogHandle

Log name

TakeoffUtime

Drone time since boot (microseconds)

CaptureUtime

Photo capture time (microseconds)

Latitude

Drone latitude (degrees)

Longitude 

Drone longitude (degrees)

AbsoluteAltitude

Absolute altitude above sea level (meters)

VehiclePositionNED

Position of the drone in the hybrid frame (north-east-down; meters)

VehicleSpeedNED

Velocity of the drone in the hybrid frame (north-east-down; meters /second)

VehicleOrientationNED

Orientation of the drone in the hybrid frame (roll, pitch, yaw; degrees)

VehicleOrientationQuatNED

Orientation of the drone in the hybrid frame (quaternion)

CameraPositionNED

Position of the sensor package in the hybrid frame (north-east-down; meters)

CameraOrientationNED

Orientation of the gimbal in the hybrid frame (roll, pitch, yaw; degrees)

CameraOrientationQuatNED

Orientation of the gimbal in the hybrid frame (quaternion)

VehiclePositionFLU

Position of the drone in the visual frame (forward-left-up; meters)

VehicleSpeedFLU

Velocity of the drone in the visual frame (forward-left-up; meters /second)

VehicleOrientationFLU

Orientation of the drone in the visual frame (roll, pitch, yaw; degrees)

VehicleOrientationQuatFLU

Orientation of the drone in the visual frame (quaternion)

CameraPositionFLU

Position of the sensor package in the visual frame (forward-left-up; meters)

CameraOrientationFLU

Orientation of the sensor package in the visual frame (roll, pitch, yaw; degrees)

CameraOrientationQuatFLU

Orientation of the gimbal in the visual frame (quaternion)

CalibratedFocalLength

Focal length of the user camera lens (pixels)

CalibratedOpticalCenter

Optical center of the user camera lens (pixels)

DewarpData

Vector of distortion coefficients specific to the camera model used

We can provide the distortion polynomial these correspond to

Orientation

Orientation of the sensor package 

  • By default, the value is "Horizontal"
  • For images captured after the sensor package rotates 180, the value is "Rotate 180"

Images captured in 3D Scan

ScanSkillStateId

UUID of this scan

The polygon prism is a bounding prism that defines the volume being scanned. It is defined by a list of 2D lat/lon points, and a min and max altitude.
PolygonPrismLatitudes

Comma-separated list of polygon vertex latitudes

Example:

"34.711897674098346, 34.711934502374667, 34.711825992904018"

PolygonPrismLongitudes

Comma-separated list of polygon vertex longitudes

Example:

"-86.654600276271509, -86.654718602075093, -86.654606026734086"

PolygonPrismMinAltitude

Minimum altitude of the polygon prism

PolygonPrismMaxAltitude

Maximum altitude of the polygon prism

The GPS position of the linearization point used as an ENU Euclidean frame for poses:

  • GpsLinearizationPointLatitude
  • GpsLinearizationPointLongitude
  • GpsLinearizationPointAltitude
Position and orientation (RDF) of the sensor package in the linearized GPS frame. These poses are the most accurate photo poses as determined by 3D Scan
  • GpsFrameCameraPosition
  • GpsFrameCameraOrientationQuat

Radiometric JPG (RJPG) Metadata

If you enable capturing Radiometric JPGs, this file embeds a 16-bit RAW Tagged Image File Format (TIFF) which can be extracted and used as a RAW thermal image.

Emissivity

0.95 (default)

  • If you set a different emissivity value, that number will reflect in the metadata
Object Distance 15.00 m
Reflected Apparent Temperature 72°F / 22°C
Atmospheric Temperature 68°F / 20°C
IR Window Temperature 77°F / 25°C
IR Window Transmission 1.00
Relative Humidity 50.0 %
Atmospheric Trans Alpha 1 0.006569
Atmospheric Trans Alpha 2 0.012620
Atmospheric Trans Beta 1 -0.002276
Atmospheric Trans Beta 2 -0.006677
Atmospheric Trans X 1.900000
Camera Temperature Range Max 248°F / 120°C
Camera Temperature Range Min -40°F / -40°C
Camera Temperature Max Clip 356°F / 180°C
Camera Temperature Min Clip -58°F / -50°C
Camera Temperature Max Warn 302°F / 150°C
Camera Temperature Min Warn -49°F / -45°C
Camera Temperature Max Saturated 392°F / 200°C
Camera Temperature Min Saturated -67°F / -55°C
Raw Thermal Image Width 640
Raw Thermal Image Height 512
Raw Thermal Image Type TIFF
Raw Thermal Image 655564 bytes

[/accordion]

Explore More

How to create 3D reconstructions

Getting Started Skydio X10

Flying Skydio X10 

 

Skydio, Inc. A0466

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