knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "images/"
)

contour2bathy

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

Installation

You can install contour2bathy from github with:

# install.packages("devtools")
devtools::install_github("jsta/contour2bathy")

Potential Tools and Workflow

Usage

 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")

Sensitivity to smallest_length threshold

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))

References

https://grass.osgeo.org/grass73/manuals/

https://grasswiki.osgeo.org/wiki/R_statistics/rgrass7



jsta/contour2bathy documentation built on June 26, 2020, 11 a.m.