- 21 Dec 2022
- 4 Minutes to read
HD Terrain Overview
- Updated on 21 Dec 2022
- 4 Minutes to read
HD Terrain is not a simple superset of the existing ground capabilities, but rather a rethinking of how the whole ground/terrain system works.
The new terrain system addresses various performance, visual quality, and editing flexibility concerns and takes advantage of modern rendering techniques by moving to more GPU-friendly data formats.
HD terrain introduces Tessellation which dynamically adds and removes polygons from the terrain. You get ultra-detail up close and better performance in the distance.
HD Terrain gives you fine control with a brush radius as small as 0.12 meters to achieve far superior ground texture compositions.
HD Terrain is a big change in approach from the old grid system. With 1,600 times more data points than the old 5m grid, we utilize a number of different techniques to allow far greater detail while still ensuring similar performance.
To achieve the flexibility and quality we're looking for, there are necessary trade-offs between performance, visuals, and accuracy. One of the main differences is a new limit of 16 unique textures per baseboard (rather than the original limit of 256 textures per route).
On a 10m grid, the minimum size you could paint a texture was 10m x 10m, with blending into the surrounding 10m grid squares.
With HD Terrain, you can now paint with a brush as small as 0.12m (lower limit subject to change based upon further testing).
By using multiple textures in that same 10m x 10m area, you can make extremely detailed scenes with every grid square looking different, and avoiding repetitive texture tiling.
As this system is still in development, it is likely that the end results will be quite different to the initial Alpha Stage implementation.
HD Terrain operates quite differently to the old 5-10m grid system. This section outlines some of the major changes and differences between the old and new systems.
- Editing HD Terrain requires S20.
- Before converting a route to use HD Terrain, first convert any legacy water to a Water Effect Layer. Legacy water is not supported with HD Terrain.
- With the old Grid system, we spent significant development and runtime resources on ensuring a seamless join between different-type baseboards (i.e. 5m and 10m boards). With HD terrain we do not support a seamless join between boards. We recommend converting the entire route to HD Terrain to avoid mismatches between the terrain types along baseboard borders.
- HD Terrain does not have "baseboard walls". Route builders should ensure that sufficient baseboards exist outside the area of the track to avoid users from seeing "under" the baseboard while driving the route.
- HD Terrain has a much longer draw distance than legacy terrain types, extending beyond your draw distance settings.
- HD Terrain uses the same data for the 3D world view and the satellite/mini-map view. This provides much greater detail when zoomed out than the old low res solution.
- HD Terrain focuses on using a smaller number of high-detail textures effectively rather than using a larger number of low-detail textures poorly. This means you can achieve much better results once you learn how to work with the new tools.
- HD Terrain has 1600x the information density of legacy terrain. To achieve this without taking terabytes of space per route, we apply “lossy compression” to the fine details. So in practice, very fine-detail edits may affect the surrounding terrain to some degree.
- You can expect a small amount of “bleeding” of textures into surrounding tiles i.e. within a meter or two of the area you are painting. This is best resolved by repainting until the desired effect is created.
- In order to maintain performance when editing large areas, some fine details may be lost when overpainting them with large brush sizes. We therefore recommend you apply larger edits first, and focus on the fine details last.
- In order to fit massive amounts of detail into limited RAM, we now use a continuous Level-Of-Detail system which keeps maximum detail near the camera and gradually reduces the detail into the distance.
- It's normal and expected that distant terrain will lack some of the finer details. It also means that the “low res” 2D textures previously used are now avoided.
- Some tools such as “Smooth Ground Under Spline” still require fine tuning. Previously the tool did not need fine-detail control such as “how wide to make the track bed” so we need to investigate how to improve the tools for HDT.
- Performance should be broadly similar to the old grids. Certain tools are slower to update due to the much larger data requirements.
- Copy/Paste for HDT is still being improved (e.g. currently some performance issues and limits on how much can be pasted).
- Textures can no longer be rotated or scaled, but the ability to paint dozens different textures in a small area, as well as apply a color tint on larger areas, should more than make up for that limitation. (We're investigating methods to allow some directional textures such as crops).
5m Terrain with Repetitive Texture
HD Terrain with Multiple Fine Detail Textures