LTDataFrame(study.area, lines, lines.psp, int.formula, det.formula,
covariates, Q.lt)covariates
or in lines. Then it extracts the values of covariates for
each observation and for dummy points. These are merged with the needed covariates
from lines and then a single dataframe is returned with the observations followed
by the dummy points. In addition, the covariate images in a list are returned to keep
with the dspat object for use in integrate.intensity.quadscheme.lt,create.covariate.images