Module: NSWTopo::DEM

Includes:
GDALGlob, Log
Included in:
Contour, Relief, Spot
Defined in:
lib/nswtopo/gis/dem.rb

Constant Summary

Constants included from Log

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

Instance Method Summary collapse

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

#blur_dem(dem_path, blur_path) ⇒ Object 



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# File 'lib/nswtopo/gis/dem.rb', line 41

def blur_dem(dem_path, blur_path)
  sigma = @smooth * @map.scale / 1000.0
  half = (3 * sigma / @resolution).ceil

  coeffs = (-half..half).map do |n|
    n * @resolution / sigma
  end.map do |x|
    Math::exp(-x**2)
  end

  vrt = OS.gdalbuildvrt "/vsistdout/", dem_path
  xml = REXML::Document.new vrt
  xml.elements.each("//ComplexSource") do |complex_source|
    kernel_filtered_source = complex_source.parent.add_element("KernelFilteredSource")
    complex_source.elements.each("SourceFilename|OpenOptions|SourceBand|SourceProperties|SrcRect|DstRect") do |element|
      kernel_filtered_source.add_element element
    end
    kernel = kernel_filtered_source.add_element("Kernel", "normalized" => 1)
    kernel.add_element("Size").text = coeffs.size
    kernel.add_element("Coefs").text = coeffs.join ?\s
    complex_source.parent.delete complex_source
  end

  log_update "%s: smoothing DEM raster" % @name
  OS.gdal_translate "/vsistdin/", blur_path do |stdin|
    stdin.write xml
  end
end

#get_dem(temp_dir, dem_path) ⇒ Object 



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# File 'lib/nswtopo/gis/dem.rb', line 5

def get_dem(temp_dir, dem_path)
  txt_path = temp_dir / "dem.txt"
  vrt_path = temp_dir / "dem.vrt"
  te = @map.bounds(margin: margin).transpose.flatten

  Dir.chdir(@source ? @source.parent : Pathname.pwd) do
    log_update "%s: examining DEM" % @name
    gdal_rasters @path do |index, total|
      log_update "%s: examining DEM file %i of %i" % [@name, index, total]
    end
  end.tap do |rasters|
    raise "no elevation data found at specified path" if rasters.none?
    log_update "%s: extracting DEM raster" % @name
  end.group_by do |path, info|
    Projection.new info.dig("coordinateSystem", "wkt")
  end.map.with_index do |(projection, rasters), index|
    raise "DEM data not in planar projection with metre units" unless projection.proj4.split(?\s).any?("+units=m")

    paths, resolutions = rasters.map do |path, info|
      [path, info["geoTransform"].values_at(1, 2).norm]
    end.sort_by(&:last).transpose

    txt_path.write paths.reverse.join(?\n)
    @resolution ||= resolutions.first

    indexed_dem_path = temp_dir / "dem.#{index}.tif"
    OS.gdalbuildvrt "-overwrite", "-input_file_list", txt_path, vrt_path
    OS.gdalwarp "-t_srs", @map.projection, "-te", *te, "-tr", @resolution, @resolution, "-r", "bilinear", vrt_path, indexed_dem_path
    indexed_dem_path
  end.tap do |dem_paths|
    txt_path.write dem_paths.join(?\n)
    OS.gdalbuildvrt "-overwrite", "-input_file_list", txt_path, vrt_path
    OS.gdal_translate vrt_path, dem_path
  end
end