Convert a pdf with contour lines to a bathymetric (raster) map loosely following https://gis.stackexchange.com/questions/93103/connecting-grass-with-r?rq=1
You can install contour2bathy from github with:
# install.packages("devtools")
devtools::install_github("jsta/contour2bathy")-
GRASS
-
R
library(contour2bathy)
pdf <- system.file("extdata/1835300a.pdf", package = "contour2bathy")
res <- contour_read(pdf_path = pdf)
par(mfrow = c(1,2))
par(mar = c(0,0,3,0))
sp::plot(res$raster,
col = "black", axes = FALSE, box = FALSE,
legend = FALSE, main = "Original PDF")
sp::plot(res$lines, main = "SpatialLinesDataFrame Object")
class(res$lines)
longest_line <- res$lines[which.max(sp::SpatialLinesLengths(res$lines)),]
sp::plot(longest_line, add = TRUE, col = "green")
par(mfrow = c(2,2))
par(mar = c(0,0,3,0))
sapply(c(0.007, 0.01, 0.015, 0.02),
function(x) sp::plot(contour_read(pdf_path = pdf,
smallest_length = x)$lines))