Offset Polygon is a solution for solving shrinking problem when polygons in a scene overlay. You can set polygon offset for scene, 3D tile cache (osgb) layer, and model dataset layer in Scene Properties, 3D Tile Cache Layer Properties, and Model Dataset Layer Properties panels respectively.

Fig. Set polygon offset

Polygon offset and scale factor determine the offset of polygon in the screen depth direction:

Depth offset=m*scale factor+r*offset constant

Among where, m indicates the largest scale factor of the polygon, r indicates the minimum value that can ensure the coordinate depth value can be recognized, which varies according to OpenGL rendering.

The figure below is comparison before and after setting offset, where offset factor and offset scale are set to -5. If you set for polygon offset of layers above the ground, you can set to 5.

Fig. Comparison before and after setting offset