producing an uniform velocity vector plot
 

Dear OpenFOAMers,

I am wondering how I can produce uniform velocity vector of the flow field using Glyph. When I unchecked the "mask points", paraview plots vector at ALL points. This is way too much for my case. I would like to reduce the number of vectors. However, if I selected the "Mask Points", then, some area has lots of vector, while some other areas have almost NO vector plotted. I am looking for plotting the vectors in a "uniform" fashion across the whole flow domain. I am wondering how I can achieve this. Suggestions will be highly appreciated.

Pei-Ying