I need to get the center point of a line or polygon to make `marker` for my app. So that when you click a marker the geometry appears (line or polygon). I used `ST_Centroid` to make it work. 

The result is what I expected unnest some polygons or lines whichs centroids are out of the geometry. What i would like for those lines or polygons is to get the "most center point" but inside the geometry. 

**How can I do this? Is there a solution?**