Reusable Textures and Modular Assets

As video game engines aren't yet all-powerful and time is precious in the video game industry, solutions had to be found in order to generate massive environments that the engine could process and load fast. 

Some of the ones I have learned and researched about are tiling/trim shits and modular assets. 

Tiling textures and trim sheets are generally used to texture large, generic surfaces and good resolutions without using huge textures and wasting unnecessary budget and time. They also preserve the Texel density that would otherwise be lost using a large texture. Even more, using a 4096x4096 or bigger to texture every part of a huge environment would immediately make the game unplayable, or at the very least drastically decrease its performance.

 While tiling textures tile in all directions, trim sheets tile only in one. 

Tiling textures and trims can be used in multiple parts of a game, even in different environments. For example, if you've made a stone tile sheet for a stone floor, that texture can be used later for a stone wall. 

Although tiling and trim sheets do have obvious repetition and can't have unique details, that can be hidden using things such as decals and props in order to distract the viewer from it and break the pattern. 

Modular assets, on the other hand, are like puzzle pieces. They are assets made to fit together in various patterns in order to build environments easily. I will give an example from Nintendo's "Legend of Zelda: Breath of the Wild" as it is the latest one I've played and I noticed the patterns in most of the environments, especially in the Zora's Domain area.

Legend of Zelda: Breath of the Wild, Zora's Domain

The arch is the same one repeated over and over again most likely. There are multiple areas surrounded by these arches in the Zora's home as the environment was surely thought-out beforehand and is using modular assets in a smart way. There are also the sharp tower pieces that are reused throughout the palace as well as the floor and the columns sustaining it above the water. I think there is one floor piece with its column that it's just repeated to create the walkways of the Domain. 

This way, this beautiful large environment has been built with a bit more over three modular pieces. 

In conclusion, reusable textures and modular assets are used to save time and budget, as well as optimize the game.