More info See in Glossary so that the user needs to do no manual assignment.

In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. Think of each unique Scene file as a unique level. Unity handles the generation and use of Sprite atlas textures behind the scenes A Scene contains the environments and menus of your game. Unity provides a Sprite Packer utility to automate the process of generating atlases from the individual Sprite textures. For optimal performance, it is best to pack graphics from several Sprite textures tightly together within a single Texture known as an atlas. However, a significant portion of a Sprite Texture will often be taken up by the empty space between the graphic elements and this space will result in wasted video memory at runtime. More info See in Glossary graphics, it is convenient to work with a separate Texture file for each character. If you are used to working in 3D, Sprites are essentially just standard textures but there are special techniques for combining and managing sprite textures for efficiency and convenience during development. When designing Sprite A 2D graphic objects. More info See in Glossary system when packing Textures. Also referred to as a texture atlas, image sprite, sprite sheet or packed texture. Existing Projects already using Sprite Packer will still be able to continue using it, however any new Project created in 2020.1 onwards will default to the Sprite Atlas A texture that is composed of several smaller textures. Please note that Sprite Packer is deprecated for Unity 2020.1 and newer, and will no longer be available as an option from Sprite Packer Modes.

Unity3d unpacker