Support Functions

This module contains functions independent of any overarching class or specific workflow, which serve to assist the user in utilizing the core functions. supportfunctions.py contains supporting functions to format intrinsic files, convert extrinsic coordinates to and from geographical and local coordinate systems, calculate extrinsic values, and other steps necessary to utilize the core functions of the CoastalImageLib library. Additionally, supportfunctions.py contains functions that interface with Argus technology, including functions to create Argus compatible filenames from UTC timestamps, and convert raw Argus files into delivery files collected from the Argus tower Argus or other mini- Argus systems. Converting raw Argus data utilizes functions contained in argusIO.py.

Function definitions and examples

Functions are grouped by usage--transform functions, intrinsic function for loading and formatting, misc. functions--and listed in alphabetical order.

Transform functions

localTransformPoints

localTransformPoints(origin, x_in, y_in, flag) source

Transforms points either in geographical coordinates to local,
or in local to geographical.
This requires the local origin in geographical coordinates, as well as the
angle between coordinate systems in CIRN angle convention.
See the WAMFlow user manual for more information on CIRN angle convention.

Args:
    origin (list or array) (xo, yo, angle): local origin (0,0) in Geographical coordinates.
            Typically xo is E and yo is N coordinate.
            The angle should be the relative angle
            between the new (local) X axis  and old (Geo)
            X axis, positive counter-clockwise from the old (Geo) X.
    flag (bool) = 1 or 0 to indicate transform direction
          Geo-->local (1) or
          local-->Geo (0)
    x_in (array) - Local (X) or Geo (E) coord depending on transform direction
    y_in (array) = Local (Y) or Geo (N) coord depending on direction

Returns:
    x_out (array) - Local (X) or Geo (E) coord depending on direction
    y_out (array) - Local (Y) or Geo (N) coord depending on direction

Example:

#World to local
origin = [0, 0, 120]
Easting = 322825
Northing = 3076150

xLocal, yLocal = localTransformPoints(
   origin,
   1,
   Easting,
   Northing
   )

Intrinsic functions: loading and formatting

initFullFileName

initFullFileName(infile, label, type="avi", return_all=False) source

Function for conveniently creating an outfile name consistent with any
naming convention, given an infile name that contains the naming style

Args:
    infile (string): name of input file
    label (string): label associated naming convention
    avi (string): file type
    return_all (bool): if true, return outstr, name, and folder.
        If false, just return outstr.

Returns: outstr (string): full formatted filepath name (string): filename folder (string): folder file lives in

Example:

infile = 'C:/Documents/examplepath/filename'
outfilepath,outfilename,folder  = initFullFileName(infile, 'CIRN', return_all=True)

loadJson

loadJson(jsonfile) source

Reads a .json file into a python dictionary.

Requires json package.

Args:
    jsonfile (string): filepath to json file

Returns:
    dictname (dict): Python dictionary created from json file

Example:

jsonfile = 'C:/Documents/example.json'
jsonDict = loadJson(jsonfile)

loadMatCIRN

loadMatCIRN(files, tag="CIRN") source

Requires scipy.io package

This function reads and formats instrinsics from .mat files, in either
CIRN camera calibration format or CIRN intrinsics format

Args:
    files: (string) file paths to .mat intrinsics file
    tag: (string) 'CIRN' or 'CalTech', indicates format of .mat file

    Note: if CIRN, extrinsics are likely included in .mat file

Returns:
    m: array of lists, length is number of cameras, each list contains
        intrinsics for the corresponding camera
    ex: array of lists, length is number of cameras, each list contains
        the extrinsics for the corresponding camera

Example:

matFile = 'C:/Documents/intrinsics.mat'
intrinsics,extrinsics = loadMatCIRN(matFile)

loadYamlDLT

loadYamlDLT(file, cams) source

Requires yaml package

This function reads and formats extrinsics and instrinsics in DLT format
from .yaml files containing camera data from one or more pre-calibrated
cameras that are labeled with a camera ID

Args:
    file: (string) .yaml file path that contains camera data
    cams: (list of strings) camera labels used in .yaml file

Returns:
    m: array of lists, length is number of cameras, each list contains
        the DLT vector for the corresponding camera
    ex: array of lists, length is number of cameras, each list contains
        the extrinsics for the corresponding camera

Example:

#Location of our calibration data, stored in a .yaml file inside this repository
calibration_loc = ('ExampleData/cameraData.yml')

#Call a support function to format .yaml files into CIRN convention
m, ex = loadYamlDLT(calibration_loc,cams)

Misc. functions

avgColor

avgColor(img) source

Calculate the average pixel intensity of an image

Input:
    img (ndarray) - np.ndarray representing image
          img read as skimage.io.imread( 'imagefilename.jpg' )
Returns:
    av (ndarray) - av (np.array of average r, g, b values), 
    avall (float) - average of r,g,b

Example:

avgRGBArr, overallAvg = avgColor(img)

estSharpness

estSharpness(img) source

Estimate image sharpness and contrast

Input:
    img (ndarray) - np.ndarray representing image
          img read as skimage.io.imread( 'imagefilename.jpg' )
Returns:
    s,c (float) - sharpness and contrast estimates

https://stackoverflow.com/questions/6646371/detect-which-image-is-sharper

Example:

sharpness, contract = estSharpness(img)