Useful Measurement Values

Questions specific to OpenMW-CS can be asked, and content development related topics can be discussed here
Post Reply
User avatar
Posts: 7
Joined: 03 Jul 2016, 18:10

Useful Measurement Values

Post by Uradamus » 04 Aug 2017, 16:24

For ages now I have been curious about the size of things in Bethesda's games, as far as what scale they were working with, often times it gets said that they use a 70 game units per meter, but that is actually off, because someone rounded the value for simplicity sake and the rounded value kept getting passed around without qualification. Going by it leads to a lot of strange fractional measurements for things that should have nice clean integer values, like the length of a cell side. I finally found the magic number though after a lot of digging around yesterday, 64 game units is equivalent to a yard, everything is based around this! Bethesda have their roots here in the US, so it isn't completely unexpected they would go with imperial units, especially since they got started long before the industry started to settle on the 1 unit = 1 meter convention.

With that in mind we can derive much more meaningful values:
- Exterior cells are 8192 game units per side or 128 yards (this is specific to Morrowind, later games used 4096 game units per side or 64 yards).
- Exterior terrain meshes are made with 32 edges per side, so each triangulated quad in a flattened terrain is 256 game units per side or 4 yards.
- Terrain elevation changes at a rate of 8 game units per increment in heightmap value or 1/8th of a yard or 4.5 inches.
- Base adult human height is 128 game units or 2 yards or 6 feet.

I plan to dig around in the assets to measure some examples to find out what measurements they went by for things like interior tiles and furnishing props. Once I do I will update this post with my findings. Also for those who are wondering, the true length of a meter in game units is actually 69.99104, which is really close to 70, so you can see why it was rounded and how the confusion started.

If you are curious to see what the cell terrain mesh looks like, I made a version in Blender to the above mentioned scale:!sU1lEIrI!sWL2QpYdWcMc ... rTxxu4lcR4

User avatar
Posts: 7
Joined: 03 Jul 2016, 18:10

Re: Useful Measurement Values

Post by Uradamus » 08 Aug 2017, 11:26

Sorry for the slow updates, but there are so many nifs to go through. I am still a long ways off from going through them all, but I've done enough of the interior bits so far to update this thread with some of the common sizes used for the small/standard sized tiles.

- Tiles are 256 GU per side, or 4 yards.
- Ceiling height is typically 236 GU, or 11 feet 3/4 inches, I'd imagine the 20 GU discrepancy is there to allow a gap between floors. So each floor should be 4 yards apart from each other.
- Single tile stairs have a 128 GU change in elevation, or 2 yards, so it would typically take 2 tiles to transition from one floor to the next.
- A single stair tile has 8 stairs that are each 16 GU high and 32 GU deep, or 9 and 16 inches respectively.
- Windows are all over the place on size and placement, no effort seemed to go into standardizing the various windows types in relation to one another, so you might as well do the same and just go with what looks best. For what it's worth though, the window sills I checked so far have been roughly in the range of about 50-75 GU for the height of their top face.

I've been going through the interior bits in order so far, and most have been fairly custom cave bits. I haven't got to any of the larger standardized tiles yet or any of the tall ones either, so I'll have to get back with their measurements later. I haven't had a chance to check out furnishing and props at all yet, so those will still be coming in a later update as well.

Once I've gone through the Morrowind nifs, I'd also like to take a look at some from Oblivion and Skyrim as well. I know Skyrim for sure uses tiles that are likely a fair bit larger, but I am not sure by how much. But they do feel like a much better size than the standard Morrowind ones, usually with a fair bit more breathing room, though they tend to use much of the extra space to give more depth and height to the decorative elements along the edges while keeping some what similar sized navigable area down the middle.

Posts: 36
Joined: 15 Sep 2013, 16:00

Re: Useful Measurement Values

Post by BlueFootedBooby » 15 Aug 2017, 18:59

Thanks for this! These numbers make a lot more sense than 70, both because Americans tend to think in feet outside of academia, and because programmers rarely pick arbitrary numbers that aren't powers of two. :V

User avatar
Posts: 7
Joined: 03 Jul 2016, 18:10

Re: Useful Measurement Values

Post by Uradamus » 16 Aug 2017, 03:12

Heh, ya, that 70 units per meter thing always really irked me. I get twitchy when it comes to non-power-of-2 units. :geek:

I am still slowly but surely importing assets to Blender a bit each day, but I also started to make some models for the Tamriel Rebuilt folks, which has slowed down my progress some. On the plus side, I have come across some more tiles to take useful measurements from including high ceilings and steeper stairs.

As for tiles with high ceilings and rafters along where the low ceilings are on the standard tiles:
- Top of ceiling is at 364 GU (20 shy of 384 GU or 6 yards, again allowing for space between floors).
- Bottom of the rafters are at 200 GU up.
- Top of the rafters are at 232 GU up.

Now for the steep stairs:
- 256 GU overall elevation change from floor to floor.
- They still have 16 stairs like the standard ones.
- The individual stairs are each 16 GU deep and 16 GU tall.
- Ceiling is 492 GU above the bottom floor (20 shy of 512 GU or 8 yards).

There are also combinations of the above two - steep stairs with tall ceilings:
- They usually have the origin level with the upper floor on these. So the stairs head down from the base level.
- When you combine the 256 GU elevation change for the stairs plus the 364 GU to the ceiling, you get an overall tile height of 620 GU (20 shy of 640 or 10 yards).

User avatar
Posts: 500
Joined: 06 Jun 2017, 05:57

Re: Useful Measurement Values

Post by Thunderforge » 01 Sep 2017, 02:02

Perhaps these should be added somewhere to the wiki so that they don't get lost in the forum?

Posts: 38
Joined: 09 Aug 2017, 05:32

Re: Useful Measurement Values

Post by JohnMaster » 18 May 2018, 09:03

The pull request discussion linked below reminded me of this thread. I very roughly created a page on the wiki but I'm not sure if or where it should be.

Display weapon reach on tooltips in feet by akortunov · Pull Request #1707 · OpenMW/openmw · GitHub

Measurement Units - OpenMW Wiki

User avatar
Posts: 6
Joined: 11 Oct 2018, 16:13

Re: Useful Measurement Values

Post by EFreya » 12 Oct 2018, 02:07

You've listed the height of an adult human in units, but do you have anything on the width/depth, and if either value changes while a person is moving?
Thanks for doing all the maths on this! :D

User avatar
Posts: 1484
Joined: 26 Mar 2013, 01:48
Location: Sweden

Re: Useful Measurement Values

Post by lysol » 12 Oct 2018, 05:04

EFreya wrote:
12 Oct 2018, 02:07
Thanks for doing all the maths on this! :D
... A year ago. :roll:
Normal mapped texture replacers, exclusive for OpenMW:
My Nexus page

Post Reply