Ocean Optics Ocean View Install - Manual (Page 95)

5: Schematic View
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Calculates and outputs the location of peaks using user-defined selections and input data.
Location: Bounds -->Peaks
Number of Inputs: 1
Type of Inputs: array
Type of Output: must be output to Metrics node
User Controls: peak finding method, minimum peak width, spatial filtering options
Notes: There are two peak finding methods available:
• Local Maxima – searches for all of the local maxima that fall within the user-defined search
parameters
• Derivative – requires that the user choose a derivative order number. A first derivative search locates
all points where the first derivative of the spectrum is zero (i.e., stationary points). A second
derivative search locates all points where the second derivative of the spectrum is zero (i.e.,
inflection points).
For either method, you must choose a minimum peak width.This parameter, measured in nanometers, will
exclude any peaks that are narrower than the user-defined value. This is useful for eliminating small,
random fluctuations due to noise.
Additionally, you can apply spatial filtering to reduce adjacent pixel discrepancies and the unwanted
effects of noise. When adjusting the Filter Span, be aware that the number of pixels used in the filter is
actually 2n+1, where n is the number displayed in the user-defined box. If 2 is entered in the box, for
example, a total of 5 pixels are used in the filter (2 to the left + 1 center pixel + 2 to the right). If the Filter
Span is set to 2, the Polynomial order number must be set to 4 or less. You can choose:
• simple Boxcar filtering -- A specialized case of Savitzky-Golay filtering where the polynomial order
is 0.
• Savitzky-Golay filtering -- The Polynomial order number must be less than the total number of
pixels used in the filter.
Photometry (Phtmet)
Calculates and outputs photometric quantities for an absolute irradiance-calibrated spectrometer.
Location: Advanced Math -->Array Math --> Photometry
Number of Inputs: 2
Type of Inputs: Unit Converter node (Absolute Irradiance), Constant (Const) (light collection area)
Type of Output: Data must be output to a Table View.
User Controls: Swap Inputs, Observer, Solid Angle (steradian)