Module: NSWTopo::Spot

Includes:
DEM, Log, Vector
Defined in:
lib/nswtopo/layer/spot.rb

Defined Under Namespace

Modules: Candidate

Constant Summary collapse

CREATE = 
%w[spacing smooth prefer extent]
DEFAULTS = 
YAML.load <<~YAML
  spacing: 15
  smooth: 0.2
  extent: 4
  symbol:
    circle:
      r: 0.2
      stroke: none
      fill: black
  labels:
    font-family: Arial, Helvetica, sans-serif
    font-size: 1.4
    margin: 0.7
    position: [right, above, below, left, aboveright, belowright, aboveleft, belowleft]
YAML

Constants included from Vector

Vector::FONT_SCALED_ATTRIBUTES, Vector::MARGIN, Vector::SVG_ATTRIBUTES

Constants included from Log

Log::FAILURE, Log::NEUTRAL, Log::SUCCESS, Log::UPDATE

Instance Method Summary collapse

Methods included from Vector

#categorise, #create, #drawing_features, #features, #filename, #labeling_features, #params_for, #render, #svg_path_data, #to_s

Methods included from DEM

#blur_dem, #get_dem

Methods included from GDALGlob

#gdal_raster?, #gdal_rasters

Methods included from Log

#log_abort, #log_neutral, #log_success, #log_update, #log_warn

Instance Method Details

#candidates ⇒ Object 



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# File 'lib/nswtopo/layer/spot.rb', line 107

def candidates
  @candidates ||= Dir.mktmppath do |temp_dir|
    raw_path = temp_dir / "raw.tif"
    dem_hr_path = temp_dir / "dem.hr.tif"
    dem_lr_path = temp_dir / "dem.lr.tif"

    if @smooth.zero?
      get_dem temp_dir, dem_hr_path
    else
      get_dem temp_dir, raw_path
      blur_dem raw_path, dem_hr_path
    end

    low_resolution = 0.5 * @extent
    OS.gdalwarp "-r", "med", "-tr", low_resolution, low_resolution, dem_hr_path, dem_lr_path

    mask = pixels_knolls(dem_lr_path).map(&:first).to_set
    pixels, knolls = pixels_knolls(dem_hr_path) do |col, row|
      !mask.include? [(col * @mm_per_px / low_resolution).floor, (row * @mm_per_px / low_resolution).floor]
    end.entries.transpose

    locations = raster_locations dem_hr_path, pixels
    elevations = raster_values dem_hr_path, pixels

    locations.zip(elevations, knolls).map do |coordinates, elevation, knoll|
      GeoJSON::Point.new(coordinates).tap do |feature|
        feature.extend Candidate, ordering
        feature.knoll, feature.elevation = knoll, elevation
        feature["label"] = elevation.round
      end
    end
  end
end

#get_features ⇒ Object 



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# File 'lib/nswtopo/layer/spot.rb', line 141

def get_features
  selected, remaining = [], AVLTree.new
  spatial_index = RTree.load(candidates, &:bounds)

  candidates.each.with_index do |candidate, index|
    log_update "%s: examining candidates: %.1f%%" % [@name, 100.0 * index  / candidates.length]
    spatial_index.search(candidate.bounds(buffer: @spacing)).each do |other|
      next if other == candidate
      next if [candidate, other].map(&:coordinates).distance > @spacing
      candidate.conflicts << other
    end
  end.each do |candidate|
    remaining << candidate
  end

  while chosen = remaining.first
    log_update "%s: choosing candidates: %i remaining" % [@name, remaining.count]
    selected << chosen
    removals = Set[chosen] | chosen.conflicts
    removals.each do |candidate|
      remaining.delete candidate
    end.map(&:conflicts).inject(&:|).subtract(removals).each do |other|
      remaining.delete other
      other.conflicts.subtract removals
      remaining.insert other
    end
  end

  GeoJSON::Collection.new projection: @map.projection, features: selected
end

#margin ⇒ Object 



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# File 'lib/nswtopo/layer/spot.rb', line 21

def margin
  { mm: 3 * @smooth }
end

#ordering ⇒ Object 



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# File 'lib/nswtopo/layer/spot.rb', line 69

def ordering
  @ordering ||= case @prefer
  when "knolls" then Candidate::PreferKnolls
  when "saddles" then Candidate::PreferSaddles
  else Candidate::PreferNeither
  end
end

#pixels_knolls(dem_path, &block) ⇒ Object 



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# File 'lib/nswtopo/layer/spot.rb', line 77

def pixels_knolls(dem_path, &block)
  Enumerator.new do |yielder|
    log_update "%s: calculating aspect map" % @name
    aspect_path = dem_path.sub_ext ".bil"
    OS.gdaldem "aspect", dem_path, aspect_path, "-trigonometric"
    aspect = ESRIHdr.new aspect_path, -9999

    offsets = [-1..1, -1..1].map(&:entries).inject(&:product).map do |row, col|
      row * aspect.ncols + col - 1
    end.values_at(0,3,6,7,8,5,2,1,0)

    aspect.nrows.times do |row|
      log_update "%s: finding flat areas: %.1f%%" % [@name, 100.0 * (row + 1) / aspect.nrows]
      aspect.ncols.times do |col|
        offsets.map!(&:next)
        next if row < 1 || col < 1 || row >= aspect.nrows - 1 || col >= aspect.ncols - 1
        next if block&.call col, row
        ccw, cw = offsets.each_cons(2).inject([true, true]) do |(ccw, cw), (o1, o2)|
          break unless ccw || cw
          a1, a2 = aspect.values.values_at o1, o2
          break unless a1 && a2
          (a2 - a1) % 360 < 180 ? [ccw, false] : [false, cw]
        end
        yielder << [[col, row], true] if ccw
        yielder << [[col, row], false] if cw
      end
    end
  end
end

#raster_locations(path, pixels) ⇒ Object 



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# File 'lib/nswtopo/layer/spot.rb', line 33

def raster_locations(path, pixels)
  OS.gdaltransform "-output_xy", path do |stdin|
    pixels.each { |pixel| stdin.puts "%i %i" % pixel }
  end.each_line.map do |line|
    line.chomp.split(?\s).map(&:to_f)
  end
end

#raster_values(path, pixels) ⇒ Object 



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# File 'lib/nswtopo/layer/spot.rb', line 25

def raster_values(path, pixels)
  OS.gdallocationinfo "-valonly", path do |stdin|
    pixels.each { |pixel| stdin.puts "%i %i" % pixel }
  end.each_line.map do |line|
    Float(line) rescue nil
  end
end