Question About Source Engine Units

Hello, I am new here, and I have question about Source Engine unit’s. Is 1 map unit equal to 1 inch or 0.75 inch, as it was stated on Valve developer page along with the other measurements?

Valve Developer Page link

Map Grid Imperial Metric

 1  =   0.75"   =   19.05mm
 2  =   1.5"    =   38.10mm
 4  =   3"      =   76.20mm
 8  =   6"      =  152.40mm
16  =   1'      =  304.80mm
32  =   2'      =  609.60mm
64  =   4'      =    1.22m

128 = 8’ = 2.44m
(160 = 10’ = 3.05m
256 = 16’ = 4.88m
512 = 32’ = 9.75m

Player Collision Hull
32 = 2’ 0" width & length
36 = 2’ 3" height crouching
72 = 4’ 6" height standing

Player Eyelevel
28 = 1’ 9" height crouching
64 = 4’ 0" height standing

Architecture
128 = 8’ 0" normal corridor height
64 = 4’ 0" normal corridor width
108 = 6’ 9" normal door height
48 = 3’ 6" normal door width

it’s 0.75 inch, yeah

Is it true that 72 * 19.05 mm = 1371.6 mm height for the player in map? and was there someshort of purpose to scale down players and NPC’s in the game in the first place? or what is this Valve’s way of doing this?

It’s 1:1. It’s even documented in the sdk code. You can also see by the player height that it’s 1:1. The player is 72 units tall which is 6’ tall, if it was 0.75" then the player would be 4.5’ tall, quite the difference wouldn’t you say?

That page is wrong, I don’t know why it hasn’t been corrected yet.

1 unit is 1 inch.

Source?

Various sources I’ve heard around from developers and others, including from sdk documentation.
Also that Source is built on the quake engine, which uses that.

If 1:0.75, then the player is about 4’, which wouldn’t make sense, but at 1:1, the player is 6’, which is more accurate.

Architecture, however, does sorta use a 1:0.75 scale, this might be where that comes from.
Building levels where 1 unit = 1 inch usually results in cramped areas and a smaller feeling of space.

However, the real world scale of a unit isn’t a constant, it’s only how it is because of how the assets have been made.

Even between the Source Engine Games from Valve, the height is inconstant:

So, the idea is to make the world feel bigger to travel that way, by scaling it?