A mathematical solution is described to reconstruct 3-D objects in the stereotactic space from angiographic, not necessarily perpendicular 2-D projections. The mathematical calculation requires 6 markers, whose coordinates should be known within the stereotactic frame reference system. This method was developed to improve the planning in stereotactic radiosurgery of AVM. An AVM nidus can be geometrically described as delineated on plane film angiography. This approach provides a more accurate determination of the lesion shape, size, angulation and position when using information from stereotactic planar angiograms. Further more this technique supports a stereotactically accurate projection of the surface volume model of the AVM nidus on to the corresponding CT and MRI scans images.