Get it here . Blocky surfaces with many sharp angles will probably have a better appearance if you do not use this option. The current version of q3map contains one or more bugs that produce visual glitches in some complex surfaces unless the detail property is used. For surfaces that don't do much to block visibility, using the detail property will not result in any performance degradation. If you do not use this texture with detail brushes, all sides of the terrain surface brushes will be seen by the game engine.
Surfaces are mirror images of each other.
Both surfaces use the detail content property. The surface on the left uses the same texture on all faces. This will make dropping a GenSurf-generated surface into another map and getting the edges matched up with existing brushes trivially easy. When it can be avoided, don't overlap GenSurf-generated surfaces. Overlapping surfaces won't cause any big problems, but will very likely produce more brush fragmentation than a group of surfaces that don't overlap.