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Camera Calibration / How does Agisoft calculate the reflectance values for the calibration panel
« on: April 15, 2021, 09:29:09 PM »
Hi all,
Didn't find this mentioned earlier so made a new topic.
I am curious on how the reflectance values are calculated in agisoft based on the .csv file for the calibration detection module.
So for the following bands with these specific wavelengths, how does Agisoft reach the reflectance value per band?
Blue (B): 475 nm ± 32 nm;
Green (G): 560 nm ± 27 nm;
Red (R): 668 nm ± 14 nm;
Red edge (RE): 717 nm ± 12 nm;
Near-infrared (NIR): 842 nm ± 57 nm
when I am manually trying to calculate this with a script like below, I get these values
dtype: float64, reflectance 0.691253
dtype: float64, reflectance 0.702969
dtype: float64, reflectance 0.69715
dtype: float64, reflectance 0.688833
dtype: float64, reflectance 0.43085
import pandas as pd
reflectance_factors_excel_path = r"RP02-1603082-SC.xlsx"
df = pd.read_excel(reflectance_factors_excel_path)
df.info()
df2 = refl_df.set_index('wavelength')
middle_nm = 842
nm = 57
nm = int(nm/2)
first = int(middle_nm - (nm))
last = int(middle_nm + (nm))
row_list = list(range(first,last))
df2.loc[row_list].mean()
But agisoft gives different values, so I would like to know the details on how we get from csv to the panel calibration reflectance value if possible!
Kind regards,
Christina
Didn't find this mentioned earlier so made a new topic.
I am curious on how the reflectance values are calculated in agisoft based on the .csv file for the calibration detection module.
So for the following bands with these specific wavelengths, how does Agisoft reach the reflectance value per band?
Blue (B): 475 nm ± 32 nm;
Green (G): 560 nm ± 27 nm;
Red (R): 668 nm ± 14 nm;
Red edge (RE): 717 nm ± 12 nm;
Near-infrared (NIR): 842 nm ± 57 nm
when I am manually trying to calculate this with a script like below, I get these values
dtype: float64, reflectance 0.691253
dtype: float64, reflectance 0.702969
dtype: float64, reflectance 0.69715
dtype: float64, reflectance 0.688833
dtype: float64, reflectance 0.43085
import pandas as pd
reflectance_factors_excel_path = r"RP02-1603082-SC.xlsx"
df = pd.read_excel(reflectance_factors_excel_path)
df.info()
df2 = refl_df.set_index('wavelength')
middle_nm = 842
nm = 57
nm = int(nm/2)
first = int(middle_nm - (nm))
last = int(middle_nm + (nm))
row_list = list(range(first,last))
df2.loc[row_list].mean()
But agisoft gives different values, so I would like to know the details on how we get from csv to the panel calibration reflectance value if possible!
Kind regards,
Christina
. Thanks for the clarity. It is a bit of a shame that the orthomosaic image in the exported processing report when using calibrated imagery (reflectace) is mostly black. As we are processing the data fully automatic I cannot determine the contrast and brightness values myself. Although maybe a default values will work in most cases. I will do some testing. 
