Feature extraction: percentage of missing values by column

A good quality of 3d scans is crucial for an assessment of similarity of striation marks between different bullets. Here, we measure the percentage of missing values in the scan. Generally, a higher percentage of missing values is associated with a lower scan quality.

extract_na_column(x3p)

Arguments

x3p

scan in x3p format

Value

percentage of missing values in each column of the scan's surface matrix

Examples

data(fau277_bb_l2)
nas_bad <- extract_na_column(fau277_bb_l2)
plot(nas_bad) # the 'feathering' becomes obvious in the spikes of the missing values


nas_good <- extract_na_column(fau001_ba_l1) # good scan
plot((1:length(nas_good))*3, nas_good, col =2)
points(nas_bad, col=4)