Turning line segments in to arcs, pretty transport display

Question

I am trying to turn a line segment display in to arc segment display

My linput data is encoded as a series of MultiLineString geometries,
I have tried things like st_forcecurve(st_linemerge(geom)) which turns my data in to series of very nice straight lines encoded as CompoundCurve geometries. Its there any way to acutal generate a curved line instead off a straight line.

Answer 1

It seems I am not the only one that has run in to issues like this A very similair problem

One of the answers did what I wanted. I just converted that answer in to an psql function that generates a curved arc, using a factor for how curved you want the answer, low values very curvy, high values a stright line.

--
-- Draw an arc geom between two differentlocations
--
--   point1                 must be a point starting location
--   point2                 must be a point ending location
--   arc_fractor            how curved you want the result
--   returns                a curved geometry

create or replace function mk_arg_geom(point1 geometry, point2 geometry, arc_factor integer ) 

returns geometry 
        as $$

DECLARE
        ret                 geometry;
        ret_srid            integer;
        tmp_geom            geometry;
        c_geom              geometry;
BEGIN

        ret := null;
        ret_srid:=st_srid(point1);

        tmp_geom=st_makeline(point1,point2);

        c_geom:= ST_CurveToLine('CIRCULARSTRING(' || 
                st_x(st_startpoint(tmp_geom)) || 
                ' ' || 
                st_y(st_startpoint(tmp_geom)) || 
                ', ' || 
                st_x(st_centroid(ST_OffsetCurve(tmp_geom, st_length(tmp_geom)/arc_factor, 'quad_segs=4 join=bevel'))) || 
                ' ' || 
                st_y(st_centroid(ST_OffsetCurve(tmp_geom, st_length(tmp_geom)/arc_factor, 'quad_segs=4 join=bevel'))) || 
                ', ' || 
                st_x(st_endpoint(tmp_geom)) || 
                ' ' ||  
                st_y(st_endpoint(tmp_geom)) 
                || ')');

        ret=st_setsrid(c_geom,ret_srid);

        return ret;
END;

$$
        LANGUAGE plpgsql;