Hello guys,
We’re building a game using Unreal Engine 5.8 and we have found out an annoying behavior using Displacement on Nanite Landscapes.
How we’re building our landscapes:
We’re using Houdini to Unreal plugin to easily import a heightmap, adding some modifications (erosion, …) and then creating the landscape in Unreal with the right partition parameters (Component Count, Subsections, …). We want to have a resolution of one vertex per 50cm, and our levels may vary a lot in altitude, some having a height of ~100m while some others can be more than 1km tall (mountains and stuff).
When the landscape is created, it appears in UE having some scaling. 50 for X/Y and something between 15 to +350 for Z, according to the topology. It seems it’s the proper way to import landscapes, Unreal forcing a density of 1 vertex per meter at 100 scale (so we need to scale down this by two), and adjusting the Z scale for better precision.
Everything was fine then until we decided to use Displacement. Our landscapes are Nanite and we’re using Nanite Tesselation + Displacement for tiny details.
Where it goes wrong:
Displacement parameter is just a scalar, and vertices are moved along the normal. The thing is, it occurs at local object level, before applying the scale. So when my landscape is scaled like [50,50,15], having a 5cm displacement would move vertices differently along X, Y and Z. It’s very noticeable on slopes (cf screen). It seems we are stuck with this behavior. We tried to find ways to export landscape with a uniform scaling, but we failed.
Here is an example on a [100,100,100] landscape (displacement is exaggerated for the example):
And the same example on a [50,50,15] landscape:
Please notice how the spikes are distorted and bend along the X,Y plane.
Do you have some insights on this?
Thank you!