LOD cross-fade
Instead of switching level of detail on a single frame, both versions are drawn briefly, one fading in as the other fades out.
A hard swap between two LOD levels shows up as a jump in the silhouette — popping. Cross-fading hides it by drawing both the old and the new model across a transition zone, with a blend factor running from zero to one. Proper alpha blending would need sorting and bring transparency artefacts, so nearly every engine dithers instead: each pixel of one model is drawn or discarded according to a pattern, and the pattern shifts over time. Under TAA the grid melts into a smooth fade.
The cost is that the object is drawn twice during the transition, which is why the zone is kept short. Unity builds it into its LOD Group, and SpeedTree forests have leaned on it for years. Terrain usually uses geomorphing instead, sliding vertices between levels.