matchExposure {phenopix}

Match exposures retrieved from the header of (stardot) digital images

Description

This function allows to match exposure values extracted from RGB and IR images based on image timestamp

Usage

matchExposure(exposure.df=NULL, 
  exposure.RGB=NULL, exposure.IR=NULL, pattern.RGB="RGB", 
  pattern.IR="IR", tol=1, 
  matching.column='timestamp')
  

Arguments

exposure.df

A dataframe where exposures from RGB and IR images are in the same data.frame. It is however suggested to provide separate data.frames for RGB and IR images. The format of the data.frame must be as in output from the getExposure() function.

exposure.RGB

When exposure.df is NULL, this data.frame, as in output from the function getExposure(), will be used to retrieve RGB exposures

exposure.IR

When exposure.df is NULL, this data.frame, as in output from the function getExposure(), will be used to retrieve IR exposures

pattern.RGB

When exposure.df is non NULL the pattern to be matched in order to subset RGB image rows. The pattern is matched by a call to grepl()

pattern.IR

When exposure.df is non NULL the pattern to be matched in order to subset IR image rows. The pattern is matched by a call to grepl()

tol

A tolerance value to be used to match timestamps of RGB and IR images. Available values include 1 (the default; perfect matching, i.e. the RGB image and the associated IR image has the same timestamp in the filename, rounded to minutes), 10, which means that images recorded within 10 minutes between each other are considered as matched. Higher values are allowed but it is suggested to avoid them

matching.column

A character giving the name of the column that must be used for the matching.

Details

This function is designed to receive in input two data.frames as in output from getExposure(), one with RGB exposures and one with IR exposures. Alternatively, one can provide a single data.frame with both RGB and IR exposures, and specify patterns of the image name (column 'images' as output from getExposure()) to match the two image types. Duplicates in image names are removed prior to the matching.

Value

A data.frame with exposure values for both RGB and IR images, the original timestamps and the rounded time.stamp. The format is suited to enter NDVI() function.

Author(s)

Jeroen Staab <[e-mail]>, Gianluca Filippa <[e-mail]>

See Also

getExposure NDVI