Location: PHPKode > projects > Keepright > keepright/checks/0050_almost-junctions.php

-- almost-junctions

ways that end somewhere, where just some meters are missing for a junction with the next way
(these almost-junctions will almost always occur not with another node, but with a way-segment just passing by)

find not-connected endpoints of highways.
find ways whose bouding box contains the end node
note ways that come closer than min_distance to the endpoint 

	query("DROP TABLE IF EXISTS _tmp_ways", $db1);

	// tmp_ways will contain all highways with their first and last node id
	// as well as a linestring of all nodes and the bounding box
		CREATE TABLE _tmp_ways (
		way_id bigint NOT NULL,
		first_node_id bigint,
		last_node_id bigint,
		PRIMARY KEY (way_id)
	", $db1);
	query("SELECT AddGeometryColumn('_tmp_ways', 'geom', 4326, 'LINESTRING', 2)", $db1, false);
	query("SELECT AddGeometryColumn('_tmp_ways', 'bbox', 4326, 'POLYGON', 2)", $db1, false);

	// find any highway-tagged way
		INSERT INTO _tmp_ways (way_id, first_node_id, last_node_id, geom, bbox)
		SELECT w.id, w.first_node_id, w.last_node_id, w.geom, w.bbox
		FROM ways AS w
			SELECT way_id
			FROM way_tags AS t
			WHERE t.way_id=w.id AND t.k='highway'
	", $db1);

	query("CREATE INDEX idx_tmp_ways_first_node_id ON _tmp_ways (first_node_id)", $db1, false);
	query("CREATE INDEX idx_tmp_ways_last_node_id ON _tmp_ways (last_node_id)", $db1, false);
	query("CREATE INDEX idx_tmp_ways_bbox ON _tmp_ways USING gist (bbox);", $db1);

	// find the first and last node of given ways

	// _tmp_end_nodes will store first- or last-nodes of given ways that are not connected to any other way
	query("DROP TABLE IF EXISTS _tmp_end_nodes", $db1);
		CREATE TABLE _tmp_end_nodes (
		way_id bigint NOT NULL,
		node_id bigint NOT NULL,
		x double precision,
		y double precision,
		PRIMARY KEY (node_id))
	", $db1);
	query("SELECT AddGeometryColumn('_tmp_end_nodes', 'geom', 4326, 'POINT', 2)", $db1);
	add_insert_ignore_rule('_tmp_end_nodes', 'node_id', $db1);

	// find first nodes that are end-nodes (that are found in way_nodes just once)
		INSERT INTO _tmp_end_nodes (way_id, node_id)
		SELECT w.way_id, w.first_node_id
		FROM _tmp_ways w INNER JOIN way_nodes wn ON w.first_node_id=wn.node_id
		GROUP BY w.way_id, w.first_node_id
		HAVING COUNT(wn.way_id)=1
	", $db1);
	// find last nodes that are end-nodes (that are found in way_nodes just once)
	// lacking the INSERT IGNORE syntax in postgres we need to exclude nodes
	// that already exist in _tmp_end_nodes (subquery)
		INSERT INTO _tmp_end_nodes (way_id, node_id)
		SELECT w.way_id, w.last_node_id
		FROM _tmp_ways w INNER JOIN way_nodes wn ON w.last_node_id=wn.node_id
			SELECT * FROM _tmp_end_nodes AS tmp
			WHERE tmp.node_id=w.last_node_id
		GROUP BY w.way_id, w.last_node_id
		HAVING COUNT(wn.way_id)=1
	", $db1);

	// now remove nodes that have noexit=yes tags
	// as they are marked as dead ends of roads intentionally
		DELETE FROM _tmp_end_nodes en
			SELECT node_id
			FROM node_tags AS t
			WHERE t.node_id=en.node_id AND t.k='noexit' and t.v='yes'
	", $db1);

	// retrieve the x/y values
		UPDATE _tmp_end_nodes en
		SET geom=n.geom, x=n.x, y=n.y
 		FROM nodes n
		WHERE en.node_id=n.id
	", $db1);
	query("CREATE INDEX idx_tmp_end_nodes_geom ON _tmp_end_nodes USING gist (geom);", $db1);

	$bi=new BufferedInserter('_tmp_errors', $db4);

	// join end_nodes and ways on "node inside bounding box of way"
		SELECT en.way_id, en.node_id, en.x AS node_x, en.y AS node_y, w.way_id AS nearby_way_id, ST_distance(w.geom, en.geom) AS distance
		FROM _tmp_end_nodes en, _tmp_ways w
		WHERE w.bbox && en.geom AND
		ST_DWithin(w.geom, en.geom, {$check0050_min_distance}) AND
		ORDER BY en.node_id, distance
	", $db1);

	// examine nodes that are close to ways in more detail:
	// there are short final segments on dead ended roads that would end
	// up as false-positives.
	while ($row=pg_fetch_array($result)) {

		if ($row['node_id'] == $last_node_id) continue;
		if (connected_directly($row['nearby_way_id'], $row['way_id'], $row['node_x'], $row['node_y'], $db3)) {

			//echo "way #{$row['nearby_way_id']} gets skipped\n";

		} else {
			//echo "way #{$row['nearby_way_id']} is too close\n";
			$bi->insert("$error_type\tnode\t{$row['node_id']}\tThis node is very close but not connected to way #{$row['nearby_way_id']}\tNOW()\t\\N\t\\N");


	query("DROP TABLE IF EXISTS _tmp_ways", $db1);
	query("DROP TABLE IF EXISTS _tmp_end_nodes", $db1);

// this function does a very simplified lookup to find out if two ways
// are connected __directly__ (they share a common node)
// and if the connection is not more than 3*$check0050_min_distance away from
// the node under test
// this is used to avoid false-positives on last-segments of ways
// that are shorter than our threshold. They shall not be checked
// against ways to which they ARE connected.
function connected_directly($way_id1, $way_id2, $NuT_x, $NuT_y, $db) {
	global $check0050_min_distance;

		FROM way_nodes wn1 INNER JOIN way_nodes wn2 USING (node_id)
		WHERE wn1.way_id=$way_id1 AND wn2.way_id=$way_id2 AND 
		(wn1.x-($NuT_x)) ^ 2 + (wn1.y-($NuT_y)) ^ 2 <= (3*$check0050_min_distance) ^ 2
	", $db, false);

	while ($row=pg_fetch_array($result, NULL, PGSQL_ASSOC)) {
	return $conn;

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