Matlab scatter hotmap
You basically need to plot the scatter map with varying colors for each point

scatter(x, y, [], c);


The main difficulty is to calculatec so that it’s proportional to the density. 

To do so you can divide the map into a grid of a certain resolution, say [res_x, res_y]. Then count for each grid cell how many points are there. This count is an approximation of the density at that grid cell. Finally you can assign to all points within this grid cell the c value equal this count. 

Probably you also need to normalize c to [0, 1]