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tf_raster_graph_shortest_slope_weighted_path

Aggregate point data into x/y bins of a given size in meters to form a dense spatial grid, computing the specified aggregate (using agg_type) across all points in each bin as the output value for the bin. A Gaussian average is then taken over the neighboring bins, with the number of bins specified by neighborhood_fill_radius, optionally only filling in null-valued bins if fill_only_nulls is set to true.

The graph shortest path is then computed between an origin point on the grid specified by origin_x and origin_y and a destination point on the grid specified by destination_x and destination_y, where the shortest path is weighted by the nth exponent of the computed slope between a bin and its neighbors, with the nth exponent being specified by slope_weighted_exponent. A max allowed traversable slope can be specified by slope_pct_max, such that no traversal is considered or allowed between bins with absolute computed slopes greater than the percentage specified by slope_pct_max.

SELECT * FROM TABLE(
    tf_raster_graph_shortest_slope_weighted_path(
        raster => CURSOR(
            SELECT x, y, z FROM table
        ),
        agg_type => <'AVG'|'COUNT'|'SUM'|'MIN'|'MAX'>,
        bin_dim => <meters>,
        geographic_coords => <true/false>,
        neighborhood_fill_radius => <num bins>,
        fill_only_nulls => <true/false>,
        origin_x => <origin x coordinate>,
        origin_y => <origin y coordinate>,
        destination_x => <destination x coordinate>,
        destination_y => <destination y coordinate>,
        slope_weighted_exponent => <exponent>,
        slope_pct_max => <max pct slope>
    )

Input Arguments

Output Columns

/* Compute the shortest slope weighted path over a 30m Copernicus 
Digital Elevation Model (DEM) input raster comprising the area around Mt. Everest,
to compute the shorest slope-weighted path from the plains of Nepal to the peak */

create table mt_everest_climb as
select
  path_step,
  st_setsrid(st_point(x, y), 4326) as path_pt
from
  table(
    tf_raster_graph_shortest_slope_weighted_path(
      raster => cursor(
        select
          st_x(raster_point),
          st_y(raster_point),
          z
        from
          copernicus_30m_mt_everest
      ),
      agg_type => 'AVG',
      bin_dim => 30,
      geographic_coords => TRUE,
      neighborhood_fill_radius => 1,
      fill_only_nulls => FALSE,
      origin_x => 86.01,
      origin_y => 27.01,
      destination_x => 86.9250,
      destination_y => 27.9881,
      slope_weight_exponent => 4,
      slope_pct_max => 50
    )
  );

tf_raster_graph_shortest_slope_weighted_path

SELECT * FROM TABLE(
    tf_raster_graph_shortest_slope_weighted_path(
        raster => CURSOR(
            SELECT x, y, z FROM table
        ),
        agg_type => <'AVG'|'COUNT'|'SUM'|'MIN'|'MAX'>,
        bin_dim => <meters>,
        geographic_coords => <true/false>,
        neighborhood_fill_radius => <num bins>,
        fill_only_nulls => <true/false>,
        origin_x => <origin x coordinate>,
        origin_y => <origin y coordinate>,
        destination_x => <destination x coordinate>,
        destination_y => <destination y coordinate>,
        slope_weighted_exponent => <exponent>,
        slope_pct_max => <max pct slope>
    )

Input Arguments

Parameter

Description

Data Types

Output Columns

/* Compute the shortest slope weighted path over a 30m Copernicus 
Digital Elevation Model (DEM) input raster comprising the area around Mt. Everest,
to compute the shorest slope-weighted path from the plains of Nepal to the peak */

create table mt_everest_climb as
select
  path_step,
  st_setsrid(st_point(x, y), 4326) as path_pt
from
  table(
    tf_raster_graph_shortest_slope_weighted_path(
      raster => cursor(
        select
          st_x(raster_point),
          st_y(raster_point),
          z
        from
          copernicus_30m_mt_everest
      ),
      agg_type => 'AVG',
      bin_dim => 30,
      geographic_coords => TRUE,
      neighborhood_fill_radius => 1,
      fill_only_nulls => FALSE,
      origin_x => 86.01,
      origin_y => 27.01,
      destination_x => 86.9250,
      destination_y => 27.9881,
      slope_weight_exponent => 4,
      slope_pct_max => 50
    )
  );