Fig. 1. Church model. Geometry around textures (outlined in red) is warped.

Fig. 3. No geometry warping (texture outlined in red). (a,b) Eye moves away from texture-viewpoint. (c) For clarity, geometry is rendered in wireframe.

Fig. 5. Texture-to-Geometry Transition. (a) Texture (outlined in red) is about to be returned to geometry. (b) Midpoint of morphing sequence. (c) Geometry has been fully restored.

Fig. 4. Geometry warping. (a,b) Eye moves away from texture-viewpoint. Notice the geometric continuity at the boundary. (c) For clarity, geometry is rendered in wireframe.

Fig. 7. Sequence of transformations for geometry warping. We first project along d_i onto the plane of the quadrilateral using the interpolated view frustum or the texture view frustum (in the latter case, p_i=p_a, P_i=P_a and M_i=M_a).

Fig. 8. Common viewpoint, adjacent textures. (a) Textures at equal view depth, thus will maintain geometric continuity. (b) Varying view depth but same at the seams, geometric continuity maintained. (c) Discontinuous view depth, geometric continuity not maintained. This case can easily be avoided.

Fig. 9. Smooth transitions. (a) Removing a texture at the edge of a string of adjacent textures, interpolation required. (b) Removing a texture in the middle of a string of adjacent textures, no interpolation.

Fig. 10. Multiple textures. Different viewpoints and distances.

Fig. 6.

Model partitioning for geometry warping. Each box corresponds to a space-partitioning box. The boxes are classified: near, texture and surrounding. Intersected boxes can be optionally partitioned.

Fig. 11. Warping sequence. A geometry-to-texture transition goes from (a) to (c). At the end of the transition, the texture is introduced. A texture-to-geometry transition goes from (c) to (a). From the texture-viewpoint, the objects look the same at all times.

Fig. 12. (a) Portal Culling. (b) Portal Texture Culling.

Fig. 2. Brooks House model. Portals have been replaced with textures.

Table 1. Performance summary