Use mipmap streaming

To enable mipmap streaming, follow these steps:

Go to Edit > Project Settings > Quality.
In the Textures section, enable Mipmap Streaming.

By default, this enables mipmap streaming for all the camerasA component which creates an image of a particular viewpoint in your scene. The output is either drawn to the screen or captured as a texture. More info
See in Glossary in your project.

In the Editor, mipmap streaming is active in both Edit mode and Play mode by default. For more information about configuring mipmap streaming in the Editor, refer to Editor settings

Make a texture work with mipmap streaming

Follow these steps:

Select a texture asset in the Project window.
In the Texture Import Settings window, select Advanced to open advanced settings.
Ensure that Generate Mipmap is enabled.
Enable Stream Mipmap Levels.

If you build your project for Android, you must also follow these steps:

Open the Build Profiles window.
Set CompressionA method of storing data that reduces the amount of storage space it requires. See Texture Compression, Animation Compression, Audio Compression, Build Compression.
See in Glossary Method to LZ4 or LZ4HC.

Lightmaps

To enable mipmap streaming for lightmapsA pre-rendered texture that contains the effects of light sources on static objects in the scene. Lightmaps are overlaid on top of scene geometry to create the effect of lighting. More info
See in Glossary, follow these steps:

Go to Edit > Project Settings > Player.
In the Other Settings section, enable Lightmap Streaming.

You can edit the mipmap streaming settings of the lightmap assets in the same way that you can edit settings of any other texture, but they reset to their default values when Unity regenerates the lightmaps. To solve this, you can tell Unity to apply these values when it generates the lightmaps. Use the Lightmap Streaming Enabled and Streaming Priority in the Player settings window.

Custom meshes

If you create a custom meshThe main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons. More info
See in Glossary in a Unity script, Unity doesn’t automatically calculate the UV density of the mesh. This means Unity loads the wrong mipmap levels.

To prevent this, do either of the following:

Use the Mesh.RecalculateUVDistributionMetrics API to manually calculate the UV density of the mesh after you create it.
Import the mesh as a model file instead.

Objects that don’t have a standard Renderer component

Unity can’t calculate the correct mipmap level for the following objects, because they don’t use a standard Renderer component:

Decals textures.
Reflection ProbeA rendering component that captures a spherical view of its surroundings in all directions, rather like a camera. The captured image is then stored as a Cubemap that can be used by objects with reflective materials. More info
See in Glossary textures, because they use mipmap levels to store lookup tables for material roughness.
SpritesA 2D graphic objects. 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. More info
See in Glossary, which use a Sprite RendererA component that lets you display images as Sprites for use in both 2D and 3D scenes. More info
See in Glossary component.
ShadersA program that runs on the GPU. More info
See in Glossary that use UV texture coordinates in a channel other than Mesh.uv (also called UV0).
Shaders that change texture coordinates other than scale and translation.

For these objects, use the Texture2D.requestedMipmapLevel API to override mipmap streaming and set mipmap levels manually. If you don’t do this, Unity uses low-resolution mipmap levels, which might display as blurry depending on the distance from the camera.

Additional resources

Introduction to mipmap streaming

Configure mipmap streaming