The Surrogate Tools allow you to manage the creation of large sets of spatial surrogates and also supports merging and gapfilling of surrogates. (only Java components)
Line surrogates for both gridded and polygon output surrogates do not work when there is a county with a hole in the middle, i.e. donut hole. The surrogate fractions in these cases calculate to be > 1.0 because the intersection with the outer part of the county is not being resolved correctly. The work around is to use the normalization tool to get the surrogates to add to 1.0. Note this issue in the release notes
Line surrogates for both gridded and polygon output surrogates do not work when there is a county with a hole in the middle, i.e. donut hole. The surrogate fractions in these cases calculate to be > 1.0 because the intersection with the outer part of the county is not being resolved correctly. The work around is to use the normalization tool to get the surrogates to add to 1.0. Note this issue in the release notes