geo_line_interpolate_point()

Calculates a point at fraction value on a line on Earth.

Syntax

geo_line_interpolate_point(lineString,fraction)

Parameters

Returns

The point coordinate value in GeoJSON Format and of a dynamic data type on line string at the specific fraction value. If the line or fraction value is invalid, the query produces a null result.

LineString definition and constraints

dynamic({“type”: “LineString”,“coordinates”: [[lng_1,lat_1], [lng_2,lat_2], …, [lng_N,lat_N]]})

• LineString coordinates array must contain at least two entries.
• Coordinates [longitude, latitude] must be valid where longitude is a real number in the range [-180, +180] and latitude is a real number in the range [-90, +90].
• Edge length must be less than 180 degrees. The shortest edge between the two vertices is chosen.

Examples

The following example calculates a point at 25% location since line start.

let line = dynamic({"type":"LineString","coordinates":[[-73.95796, 40.80042], [-73.97317, 40.764486]]});
print point = geo_line_interpolate_point(line, 0.25);

Output

The following example calculates point longitude at 90% since line start.

let line = dynamic({"type":"LineString","coordinates":[[-73.95807266235352,40.800426144169315],[-73.94966125488281,40.79691751000055],[-73.97317886352539,40.764486356930334],[-73.98210525512695,40.76786669510221],[-73.96004676818848,40.7980870753293]]});
print point = geo_line_interpolate_point(line, 0.9)
| project lng = point.coordinates[0]

Output

The following example visualizes point on a map.

let line = dynamic({"type":"LineString","coordinates":[[-73.95807266235352,40.800426144169315],[-73.94966125488281,40.79691751000055],[-73.97317886352539,40.764486356930334],[-73.98210525512695,40.76786669510221],[-73.96004676818848,40.7980870753293]]});
print point = geo_line_interpolate_point(line, 0.9)
| render scatterchart with (kind = map)

The following example returns true because of the invalid line.

print is_bad_line = isnull(geo_line_interpolate_point(dynamic({"type":"LineString","coordinates":[[1, 1]]}), 0.5))

Output