Estimation of the twist in a barrel follows roughly the process described by Chu et al (2010). At the moment, twist is estimated from a single land - but the twist should be the same for the whole barrel. Therefore all lands of the same barrel should have the same twist. A note on timing: at the moment calculating the twist rate for a bullet land takes several minutes. XXX TODO XXX make the different methods a parameter. Also, accept other input than the path - if we start with the flattened bulletland we get results much faster.
getTwist(path, bullet = NULL, twistlimit = NULL, cutoff = 0.75)
| path | to a file in x3p format |
|---|---|
| bullet | data in x3p format as returned by function read_x3p |
| twistlimit | Constraint the possible twist value |
| cutoff | Use this for the quantile cutoff |
numeric value estimating the twist
# NOT RUN { # execution takes several minutes load("data/b1.rda") twist <- getTwist(path="barrel 1 bullet 1", bullet = b1, twistlimit=c(-2,0)*1.5625) # }