Landscape

A Landscape Actor is made up of quads, sections and components.

The Landscape Actor is the top level object and when creating a landscape it edges is shown in yellow.

The actor then contain a grid of landscape Components. From 1 to max 32 in each direction but it does not have be square. The components are Unreal's base unit of rendering, visibility calculation, and collision. Components in a Landscape are all the same size and are always square. Each component's height data is stored in a single texture. Because of this, its size has to be a power-of-two number of vertices. Vertices along the edge of two neighboring components are duplicated and stored in each component. The edges of the components is shown in light green.

Each component then is made up of 1 or 2x2 sections. The secion edges is shown in medium green and they are used to make LOD levels.

The sections then contains the individual quads of the landscape. Setting the section size select how many quads to have in each section from 7x7 to 255x255. They are in steps of power of two minus one.

Section Size

Sections per component

Number of components

Each component is saved as a texture

More components, the more expensive it is to Render

Components terrain Occlusion

Open World

16x16 km. 8 Km from origio

1m resoulution.

Break up in streaming levels

LOD mesh version for distant terrain

=== Sun Direct Lighting

Cascade Shadow Maps (CSM) near camera

- Supports foilage animation

- Large cost from triangles

Ray traced signed distance field shadows (RTDF)

- 3x more efficent for huge view range

- maintain details at distance

- A distance field stores distance to nearest surface at any point

- Ray intersection skips through empty space based on distance to surface

Sun Bounce light

- Heightfield GI. Store light in heightfield and use it to light and shade the tree's and rocks on terrain.

Shadowing

- SSAO for creases/distant. Small scale/detail AO.

- DFAO for medium scale. For trees, big rocks.

Distance Field Ambient Occlusion - DFAO

- Traces cones against mesh distance fields to determinate sky visibility

- Computed with world space occluders, no screen space artifacts

Foilage

- Trees, rocks

- Collison

- Manual/proc placement

- Tree LODS: 115k, 13k, 2500, 32

- Hierarchial instanced static mesh

- Render over million instances

- Orgianice meshes into bsp-like tree

- per-pixel lod transitions

- Use pixel depth offset on lod to improve shadows (billboard has depth for shaodws)

Grass

- Grass, flowers, pebbles

- no collision

- material driven placement

Diving Into the Depths of Water as a Feature in Unreal Engine 4.26

https://www.youtube.com/watch?v=d5Ft7UaYayM

Volumetric Clouds Overview - Unreal Engine 4.26

https://www.youtube.com/watch?v=X7MF9idvNqQ

Sky, cloud, and environment lighting in 4.26

https://www.youtube.com/watch?v=NndsCthHDDY