how to make a uniform spacing grid for non-uniform spacing grid in 3-d

i made a field of transmitter and receiver array in 3d which has non-uniform spacing in grid. i want to make a uniform spacing grid for nonuniform spacing grid. i tried but non-uniform spacing grid is not fully covered. my code is :

theta=-pi/6:pi/180:pi/6; 
phi=-pi/6:pi/180:pi/6;
[theta,phi]=meshgrid(theta,phi);
for rho=5:.025:50
    [x,y,z]=sph2cart(theta,phi,rho);  
    mesh(x,y,z,'edgecolor','r');    %field which has non-uniform spacing grid
    hold on
   % uniform spacing grid
   x1=linspace(min(x(:)),max(x(:)));
   y1=linspace(min(y(:)),max(y(:)));
    z1=linspace(min(z(:)),max(z(:)));
    [xs,ys]=meshgrid(x1,y1);
    zs=meshgrid(z1);
    mesh(xs,ys,zs,'edgecolor','g');
    hold on
end

i want that uniform grid covers the non-uniform grid. i have doubt that either i could not make the exact uniform grid or i have made the exact grid in above program and it just the visualization problem because i included the all over range of coordinates of non-uniform grid..

Please help me to solve my problem