Q: How many feet, inches or centimetres are there per Quake Unit?A: None.Long AnswerAlthough content used in Quake and other BSP based games can be modelled in various 3D applications using real world units of measurement, doing so
does not directly translate into anything meaningful in idTech (Quake/Doom engines). This is because 'unit', as that term is normally understood, is an arbitrary value relative to the real-world and other software - whilst the former has physical attributes that ensures the 'unit' has meaning, the latter does not - a simple cube measuring one inch cubed (1x1x1) exported from Blender, 3DS Max, Maya or any number of other 3D applications, may be comparatively different sizes (when placed next to each other).
This generally means when building content, for example a wall 256 "units" high, the actual 'unit' reference, i.e. whether measured in "Metric" or "Imperial" units, should be ignored in terms of preferentially indicating the size of objects because, relative to the aforementioned game engines, they have no meaning. In other words;
One "quake unit"
is not equal to one "inch", "centimeter" or "foot".
It is equal to one Quake Unit.
For example, a typical door in RtCW is 64 units wide by between 120 or 128 units high. Relative to a standard AI Soldier's physical attributes, realistically the door should be approximately 48 units wide by at most 112 high (more often 104). This doesn't work in game for two main reasons; 1) character collision boxes and 2) differential size of characters and their affect on the former - B.J. is about 6' 2" (six foot two inches) and looks down on most of the enemy AI, making them significantly smaller (which is often why they look tiny walking around a level; when building and running through a game, the players point of view is significantly different; one of the reasons why switches and buttons look fine to the player but like gigantic fairground mallet hitting targets when an AI stands next to them).
In other words, if a door is modelled properly to represent real-world sizing (approximately 2' 6" wide by 6' 6" high) it can cause navigation issues for both the player and AI because it's likely going to be too small despite being visually (or technically) correct (again relative to the real world) - doors, like everything else, need to fit the relative size of the players perspective and each characters physical dimensions, rather than being specifically 'measured' to a given size as represented by real-world units.
To ensure objects and characters are correctly sized, the best approach is to make use
of a set of Radiant/UEdit references blocks, that way everything is sized relative to a fixed, common, reference.