LoD Models¶

LoD models (an abbreviation for Level-of-Detail) are used to reduce the processing power needed to render a model far away from the camera by reducing its polygon count and other related methods.

They were first used in Sonic Frontiers, but may have been supported since Sonic Forces.

Where are LoD models found?¶

LoD models are stored in .model and .terrain-model files, alongside additional LoD-specific information on when to use each model. Note that not all model files have LoD models.

It should be noted that files with LoD models are formatted differently, and will not work in HE1 games, as well as potentially break some tools that are not equipped with recognizing and reading those formats.

Importing LoD models¶

You can import LoD models by checking the import LoD models option in the model importers:

../_images/lod_models_import.png — How to import LoD models¶

Doing this will create a new collection, to which all imported LoD models are added:

../_images/lod_models_import_collection.png — The LoD import collection¶

Configuring LoD models¶

LoD models can be configured for the followering object types:

Armatures
Meshes
Curves (mesh)
Surfaces (mesh)
Text objects (mesh)

Each of these data types has an HEIO properties panel; For armatures, it is called HEIO Armature Properties, while for the mesh types it’s called HEIO Mesh properties. In these panels you will find a sub-panel with the name “LoD Info”:

../_images/lod_models_panel.png — The lod info panels for meshes (left) and armatures (right)¶

Here you configure the individual LoD models, which are used when the object is the root of the exported object tree.

Setup¶

When first opening the LoD info subpanel you are met with a button that says “Initialize LoD Info” (unless it’s an imported object that already had LoD info):

../_images/lod_models_initialize.png — The initial LoD info panel¶

Pressing the button will create the default entry and make it possible to add more entries:

../_images/lod_models_initialized.png — The initialized LoD info panel¶

Lod info items¶

Each LoD info item in the LoD list has 3 properties:

Target

The root of the object tree to export for the LoD model. If this is missing, then the info item is ignored.

LoD Cascade

The cascade until which the model should be displayed. (Needs confirmation)

The greater the number, the further away the model gets displayed.

Unknown

We have no idea what this does yet, as the game never uses a value beside -1.

The “self” item¶

This item does not have a target, as it represents the object on which the list is stored.

How are LoD models made?¶

Unfortunately, this is where it gets a little complicated, as there is no simple 1-2 step way to creating LoD models (yet).

Sonic Team reportedly used InstaLOD for generating most, if not all LoD models, which they must have integrated into their own pipeline via plugins.

In default blender, the simplest way to creating LoD models is by using the Decimate modifier, which organically reduces the number of polygons in a model.

The recommended way to create simple LoD models right now is:

Create a duplicate of the model using the duplicate linked operator
Change the name of the duplicate object to end with the level prefix (“_lv1”, “_lv2”, etc.)
Add a decimate modifier to the duplicate and configure it to your liking
Create and configure a new LoD info item on the original object
Set the duplicate object as the target of the new LoD info item

Important

Keep in mind that LoD info is only sourced from the root of an object tree!

If your object tree has an armature and/or children, then make sure that the entire object tree is link-duplicated and that only the root object has the LoD infos!

Examples¶

Terrain¶

Here is a terrain model from Kingdom Valley from Shadow Generations:

As observable, the LoD models simply reduce the number of polygons used with each level.

Also notice how the LoD cascade does not go up to 31, which means that the terrain will not be rendered at all beyond cascade level 20 (to be confirmed).

These LoD models were most definitely automatically generated.

Model¶

Here is a platform model from Kingdom Valley from Shadow Generations:

Similar to the terrain model above, the first LoD model simply reduces the number of polygons used.

However, the second (and last) LoD model does something interesting: It is a simple box with special textures unique to the level.

While the previous models used 9 different materials, each with different textures, this model uses just one material with its own low resolution textures, which could mean that it was hand made, or at least handled differently from terrain LoD models.

This probably stems from the fact that the platforms are used very generously throughout the stages and challenges in Shadow generations, and needed special care to not impact the games performance.