Collect diurnal hyperspectral images for calibration

terraref / extractors-hyperspectral

Scripts and code relevant to the SWIR and VNIR cameras.

BSD 3-Clause "New" or "Revised" License

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Collect diurnal hyperspectral images for calibration #17

Closed dlebauer closed 7 years ago

dlebauer commented 7 years ago

@dlebauer commented on Wed Feb 22 2017

As discussed with @remotesensinglab, @czender, @smarshall-bmr

We need to image the spectralon targets every 15 min throughout the day,

The first priority is a clear day The second priority is to collect images on cloudy days

These datasets will be used in the hyperspectral calibration.

Details

Scan spectralon target of varying reflectances every 15 min over the course of a clear day
Ideally we will have 30 or 40% reflectance targets
Files should be identified, clipped to the target area, averaged within each band
Next step is to create an algorithm to use these for calibration as a function of zenith angle and downwelling radiance from the Environmental logger as described in #88

Completion Criteria

[ ] set of files for use in calibration

smarshall-bmr commented 7 years ago

We are still having difficulties getting the VNIR to run in triggered mode. Would anyone object to freerunning the VNIR for this calibration? We won't have any positional data from the gantry in this mode.

smarshall-bmr commented 7 years ago

@czender @remotesensinglab I could use some quick input here.

czender commented 7 years ago

@FlyingWithJerome and I are unsure exactly what freerunning vs. triggered means. The most important thing for the calibration is that the spectralon images are directly comparable to the HS images taken everyday with the same exposure duration.

remotesensinglab commented 7 years ago

@smarshall-bmr would please update us the difference between freerunning vs. triggered for image processing? That helps us to provide some feedback.

remotesensinglab commented 7 years ago

I think 75% or 50% reflectance targets would be ideal. The main reason for having reflectances over 1 in current calibration protocol is the overexposure. We are getting reflectance values over 1 on top canopy leaves as well, which is an indication of overexposure rather than the reflectance target issues. Higher reflectance targets may be helpful to show the dynamics of reflected light as pure vegetation/leaf reflectance can by up to 0.6.

dlebauer commented 7 years ago

@smarshall-bmr could you please define triggered vs in triggered mode? Is it in our documentation, or could you put it there?

dlebauer commented 7 years ago

@smarshall-bmr how would you propose to identify calibration files? @solmazhajmohammadi suggested naming the mission 'hyperspectral-calibration' or similar (or 'calibration' is implied by file type'.

ghost commented 7 years ago

These files have been supplied.