Constraining galactic structure parameters from a new extinction model andfour star count samples

We propose a new 3-dimensional extinction model based on the COBE/IRAS all sky reddening map. Its application to globular and open cluster data eviden ces that the COBE/IRAS reddening map has an accuracy of 18 %, but overestim ates visual absorption by a factor of 1.16. This systematic error does not change with galactic latitude and opacity significantly. The implementation of the new extinction model has optimized our galactic s tructure and kinematic model to low-galactic latitudes. Four star count sam ples distributed in different galactic directions have been compared with g alactic model simulations. Numerical experiments allow us to constrain the radial distribution of the galactic disk. The disk scale length is found to be 2250 +/- 50 pc and the displacement of the Sun from the galactic plane Z(Sun) = 27.5 +/- 6.0 pc.