Geometric Calibration

Module Outputs

Current Documentation
View legacy documentation


Deprecated in Current Release

Requirements Software operation Defining Calibration Tasks Definitions and Theory

Supported Systems

Supported Targets

Required Evidence

Test Setup

Calibration Procedure

Use in Imatest Master

Use in Imatest IT

Module settings

Module outputs

Defining a Device

Defining Distortion

Defining the System of Devices

Defining the Target

Defining a Test Capture

Defining a Test Image

Homogenous Coordinates

Projective Camera Model

Multi-Camera Systems

Distortion Models

Coordinate Systems

Rotations and Translations


 

Standard output from the Geometric Calibrator, either from Imatest Master or Imatest IT, comes in the form of a JSON-encoded structure.

This structure has the general structure, with objects in bold and arrays indicated by square brackets:

Top-level object
        <info about module run>
        devices [
               <info about device>
               intrinsics
               cam_to_cam
               ]

        captures [
               relative_to_target_origin
               images [
                      <info about image file, image points>
                       ]

               ]

 

JSON Output Description

 

Top level Object
Field Data Type Description 
Timestamp String Date time string of when the calibration was run
Version String Imatest version number
Build String Imatest build
Runtime Number  
reference_device String UUID of the reference device
distanceUnits String Distance units
devices Object or Array of Objects Description of each device
captures Object or Array of Object Description of the test capture positions
coordinate_settings Object A description of the camera settings

 

devices sub-Objects (array)
Field Data Type Description 
uuid String Unique identifier of device
name String User-provided name of device
serialNumber String User-provided serial number of device
sensorSize Array Number of pixels in the array [xSize, ySize]
pixelPitch Number The pixel pitch of the sensor
pixelPitchUnits String The units of the pixel pitch
intrinsics Object The intrinsic properties of the device
cam_to_cam Object The position of the device relative to the reference device
distortion_fit Object The distortion optimization results

 

intrinsics sub-Object
Field Data Type Description 
f Number The focal length of the device
f_units String The units of the focal length
pp Array of Numbers The principle point of the device [PPx, PPy]
skew Number  The skew of the device
alpha Number The focal length ratio of the device
distortion Object The distortion of the device

 

distortion sub-Object
Field Data Type Description 
type String The distortion model type: rad_div_poly_packed
form String The polynomial form: All, Even, Odd
coeffs Array of Numbers The distortion coefficients [K1, K2, …]
center Array of Numbers The center of distortion [CODx, CODy]

 

cam_to_cam sub-Object
Field Data Type Description 
direction String  
R Array of Array of Numbers The rotation matrix [[r11, r12, r13], [r21, r22, r23], [r31, r32, r33]]
coeffs Array of Numbers The translation to the reference device [tx, ty, tz]
center String  The units of the translation

 

distortion_fit sub-Object
Field Data Type Description 
opt_converged Boolean Indication if the optimization converged
nIters Array of Array of Numbers Number of iterations for the optimization
num_points Array of Numbers Number of image points used in the optimization
max_radius_used Number  Maximum (distorted) radius used in the optimization
fit_mean_err Number  

 

Captures sub-Object (array)
Field Data Type Description 
uuid String Unique identifier for the test capture
relative_to_target_origin Object Rotation and translation to the origin of the target
images Object or Array of Objects Description of the images used for calibration at this test position

 

relative_to_target_origin sub-Object
Field Data Type Description 
R Array of Array of Numbers The rotation matrix [[r11, r12, r13], [r21, r22, r23], [r31, r32, r33]]
coeffs Array of Numbers The translation to the reference device [tx, ty, tz]
center String  The units of the translation

 

images sub-Object
Field Data Type Description 
filename String The filename of the image
uuid String The unique identifier of the image
device_uuid String The unique identifier of the device that captured the image
reprojection_err_norm_stats Object The reprojection stats for the image
detectedPoints Array of Array of Numbers The detected saddle points in the image [[x1, x2, …], [y1, y2, …]]
reprojectedPoints Array of Array of Numbers The reprojected points that correspond to the detected points [[x1, x2, …], [y1, y2, …]]
worldPoints Array of Array of Numbers The corresponding world (target) points [[X1, X2, …], [Y1, Y2, …], [Z1, Z2, …]]

 

reprojection_err_norm_stats sub-Object
Field Data Type Description 
min Number The minimum reprojection error
mean Number The mean reprojection error
max Number The maximum reprojection error
percentile_95 Number The 95th percentile of the reprojection error

 

coordinate_settings sub-Object
Field Data Type Description 
count_from_one Number 0 if array indexing begins at 0, 1 if array indexing begins at 1
origin_loc String Origin of the array: ul (upper left), ur (upper right), ll (lower left), lr (lower right)
flip_world_axis Array of Numbers Array signifying flipped (from right-handed) world coordinate system in each axis [X, Y, Z]. 0 is not flipped, 1 is flipped.
flip_image_axis Array of Numbers Array signifying the flipped image coordinates [x, y] from positive downward and rightward. 0 is not flipped, 1 is flipped.