A ninth installment to the TQ Vault's developer blog feature is now available, this this time with Titan Quest lead engine programmer Max McGuire discussing the game's editor and terrain engine. An excerpt, as usual:
A height map system takes a very different approach and uses a large deformable mesh to represent the terrain. Each point on the mesh can be raised and lowered independently to adjust the elevation of the terrain in that location. It's generally very easy to sculpt a height map using a brush-based interface, since areas of the terrain are simply pushed and pulled until the desired shape is obtained. However, since each point on the terrain can only be moved up and down not side to side a height map cannot represent terrain features such as overhangs, land bridges and caves where terrain is on top of other terrain. Also, if the terrain is pushed or pulled to far it can appear stretched.
Tile systems have the flexibility to accurately model features like cliffs and overhangs while height maps are very easy to manipulate and naturally represent smoothly varying elevations like rolling hills. Since our goal for Titan Quest was to have all of these types of features in an easy to use package, the clear choice for us was to combine these two systems and get the best of both worlds (no pun intended!).