1 INTRODUCTION  
2 DATA  
2.1 The XSTPS-GAC Data  
2.2 The SDSS Data  
3 THE METHOD  
3.1 The Galactic model  
3.2 Halo fit  
3.3 Disk fit  
4 THE RESULTS AND DISCUSSION  
4.1 Fitting results  
4.2 Systematics  
4.3 Comparisons with other work  
5 SUBSTRUCTURES  
6 SUMMARY