Gaea Heightmap to Unreal (scale height question)

Elowan

hi there,

as far as I remember, Unreal 4 landscape Z-Scale 100% = 512 units.
So for a terrain with max. 4096m, you would have to set the Z-scale in UE to 800 (8x512=4096) to get the height of the landscape right.

At least this was my workflow, going from WorldMachine to Unreal Engine 4.22

Now, as I use Gaea and UE 4.26.1 - does this "math" still hold up?
Looks like there is some difference, when calculating the right height-scale in UE.

I got a 4033x4033 heightmap imported.
The Gaea settings look like this:

So the terrain max height (Gaea) is 2250m - 100% Z-scale in UE means 512m or units (if this hasn´t changed)
Z-scale in UE has to be 2250 divided by 512 = 4.39.

Instead of Z-scale 100, this should be 100x4.39= 439 if I am not mistaken...

But at this scale, the terrain is way too flat - roughly eyeballing, the scale for Z in UE needs to be around 850
or something like this - to fit the proportions from Gaea viewport.

Is there a way to exactly calculate, how the Z-scale value in UE has to be set?

Cheers!

Dylan_QS

Elowan This may be due to the Range setting in the build tab. What Range are you using? Normalized may be a good option if you are importing into UE. The height (tallness) of the terrain isn't always going to fit in the Terrain Definitions. It is often times lower than the default 2600m setting.

As for the math, the definitions in Gaea are really just arbitrary for the most part. All of the accurate scaling and math is done in UE and unfortunately, to avoid being an Epic Customer Service center, I don't want to mix responsibilities of who should answer scaling in UE.

Has Epic provided a response to this question before? Or a similar question?

I am more than happy to help but we should be seeing what Epic says in their documentation.

Your math looks to be accurate by just assuming what I have had to do in the past when working in UE.

Gaea also does not work with negative numbers while UE does. This makes scaling a bit tricky in UE while we know where the floor is in Gaea because it would clip the bottom and the same would be for the top, we wouldn't with UE because it would just stretch to infinity.

https://docs.unrealengine.com/5.0/en-US/landscape-technical-guide-in-unreal-engine/

^^ That document is one I referenced quite a bit on my UE projects.

When it comes to Gaea, though, I recommend playing with the different ranges in the build tab and see if they make a difference. As stated earlier, Normalized has been pretty good in the past. If you want to be technical about it, RAW is technically the most accurate but will require manual scaling which means more math.

BrianG61

I have found in all my experiments going from Gaea to Unreal, that in UE4 while importing the terrain, changing the Z scale to 260 seems to always work. This seems to be true for both 2k and 4k terrains. I hope this helps a little.

Elowan

BrianG61 Hmmm - I think this depends on the terrain size as well? like the height to lenght ratio...

I am type of person who wants to work with precise values instead of much guesswork so... I hope for the devs to chime in some day - but they are pretty inactive and silent on the forums. At least regading my topics/posts

svenrop

Hi Elowan , did you finnd a solutionn? I´m struggeling at thhe same point.

Elowan

Dylan_QS

hey Dylan,

thanks for your answer. I exported "RAW" in the past projects and for this setting, the above math do not work (terrain is way too flat in UE). So you´re right - RAW would require some other formular to get a matching terrain in UE, like you get in GAEA.

I think I will try normalized and see, if my math will work better with this export-setting.

Because we are working in digital world, there must be a consistent and correct solution to this matter.
Tricky thing is to find it 😉

Cheers!

Dylan_QS

Elowan you are absolutely right. Which is why, to this day, I don't understand why Epic deviated from the power of 2 structure.

They have their reasons and I had read them in the past. I can't remember what they were.

At the end of the day, though, the file range is the hard part to figure out as each program is going to handle them differently.

For instance, C4D with Octane and Corona doesn't mind the proportional range but Vue hates it. Vue wants Normalize. They are all pretty picky.

Let me know how your tests with other ranges fair. I'd like to help where I can.

bb245922917

Many schemes have been tested. At present, this scheme can make UE and GAEA infinitely close, but it cannot achieve 100% restoration.

Dylan_QS

bb245922917 THis is good info. Perhaps one of these days I can trial out this workflow.

ankanghosh

I found a tutorial on this and it worked for me.

Elowan

ankanghosh

Awesome 🙂

<-here it starts!

theshizon

Wow this is actually pretty ridiculous, I'm having issues and I need to dig around forums and Youtube to get a proper export to Unreal??? Hello Gaea devs!! Do you not think it would be a good idea to get a one button Unreal export solution? As far as I can tell from these videos nobody can get a true 1 to 1 export. I don't mean to sound crass, but touting Gaea as the best terrain tool in the industry and then having zero solution to exporting is a bit lame. I hope you are looking into rectifying this.

Jither

Just to simplify the calculation a bit… If CG Dealers' calculation is correct (and to my eyes, looks like it mostly is), there's a bit that actually cancels out, and some inaccuracy caused by Gaea's UI.

So:

Unreal Engine X/Y scale: 100 * [Desired resolution in meters] / [heightmap resolution]

Unreal Engine Z scale: 100 * [Gaea Scale] / 512

To explain:

CG Dealers' full calculation for X/Y makes sense. Note that Real scale would be usable for the X/Y scale, if Gaea didn't calculate it based on its "Standard" (powers of 2) resolution, rather than the UE resolution selected - and also chops off probably a few too many decimals for it to be usable. E.g. a map with Terrain Definition Scale set to 4000 and exported as 4033 will show 4000/4096 ≅ .977px/m rather than 4000/4033 ≅ .992px/m. So, you're better off doing that calculation yourself - like CG Dealers does.

As for the Z scale, CG Dealers' full calculation is:

([Gaea Height] / [max height in meters] ) multiplied by

([max height in meters] / [Gaea Height-Scale Ratio]) multiplied by

100 * (1 / 512)

1/512 is straight from Unreal Engine's documentation. And 100 is due to UE's standard unit being centimeters. Note that CG Dealers divides by his "max height in meters" only to multiply by it in the next part of the calculation. The two cancel out.

The Height-Scale Ratio in Gaea, which CG Dealers uses, is calculated simply by dividing the Terrain Definition Height by Scale - and then, again, chopping off probably a few too many decimals. So, like Real scale, better to just do that calculation yourself too - height divided by scale. But making that change shows us that we're actually multiplying by Height and dividing by Height - the two cancel out. Leaving us with 100 * [Gaea Scale] / 512.

This, of course, assuming that the rounded Real scale and Height-Scale Ratio aren't also the ones Gaea uses to save the files. 😉