Minimum distance from point to linestring on earth's surface

General Usage
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Sorry, it’s not option G it’s option L, which in GMT.jl is aliased to dist2line. (read the linked description of that option)

I know what you are after (I needed that operation several times before) and I’m sure GMT does it with ellipsoidal accuracy if needed. See this small example that is computing the closest point along the great circle line between [0 0] and [1 1] from point at [0.5 0.5]

julia> mapproject([0.5 0.5], dist2line=[0.0 0; 1 1])

1×5 GMTdataset{Float64, 2}
 Row │ col.1  col.2    col.3     col.4     col.5
─────┼───────────────────────────────────────────
   1 │   0.5    0.5  4.46581  0.499972  0.500029

The results are in meters and col3=dist, col4=lon_along_line; col5=lat_along_line

In your real case the command should be

mapproject([lon lat], dist2line=D)

and since you have 542 segments, you’ll have 542 rows. You can test it with a single segment (the first) with

mapproject([lon lat], dist2line=D[1])
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