Is there a way to make the hair strands become totally straight ( just like the lines ) and hence get a sharp hair edge with no patches? Thanks
Child-interpolation doesn’t work well on quads… use a triangulate modifier before the hair-system if your hair geometry has any quads (that will eliminate a lot of patches and make grooming more accurate, and you can generally get away with fewer parent hair particles).
Are you currently using weight painting for the distribution? Distribution on a relatively low-poly model using weight paint is not precise… if you want it precise make extra loop-cuts by the hair-line or add a new hair geometry that you shrink-wrap to the main model and untick “show emitter”- I think you did that for eyebrows?.. so just more of that.