A computer-implemented method, medium, and system for converting borehole images into three dimensional structures for numerical modeling and simulation applications are disclosed. In one computer-implemented method, multiple CT-scan images of a core sample of a rock are received, where the core sample includes a borehole, and the multiple CT-scan images are cross-section images of the core sample at multiple depths of the borehole. A triangulation process is performed on pixels of each CT-scan image and with respect to each of multiple circumferential position angles. Multiple radii of the borehole corresponding to the multiple circumferential position angles are determined for each CT-scan image. Multiple nodal coordinates of 3D numerical model mesh of the borehole are generated based on the multiple radii of the borehole. An advisory on drilling window limits of mud weight is provided based on the multiple nodal coordinates of the 3D numerical model mesh of the borehole.