Fix Landscape Deformation at Distance in UEFN with Python

Development Programming & Scripting
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1

UEFN does not currently expose the Max LOD Level property in the Landscape Details panel.

This can cause detailed Landscape shapes to become heavily simplified or deformed at a distance. However, the hidden max_lod_level property can be changed through UEFN Python editor scripting.

The video below shows a synchronized comparison using the same Landscape, camera path, and graphics settings.

  • Before: max_lod_level = -1
  • After: max_lod_level = 0

-1 is the default automatic LOD behavior.
0 restricts the Landscape to LOD 0 at all distances.

Python script

Select one or more Landscape actors in the Outliner, then run this script:

import unreal


# ============================================================
# Force LOD 0 only on the selected Landscape actors.
#
# max_lod_level:
#   -1 = Default automatic LOD behavior
#    0 = Force LOD 0 at all distances
#    1 = Allow up to LOD 1
# ============================================================

MAX_LOD_LEVEL = 0


def is_landscape_actor(actor):
    if actor is None:
        return False

    class_name = actor.get_class().get_name()

    return class_name in {
        "Landscape",
        "LandscapeProxy",
        "LandscapeStreamingProxy",
    }


def describe_actor(actor):
    return (
        f"{actor.get_actor_label()} "
        f"({actor.get_class().get_name()})"
    )


actor_subsystem = unreal.get_editor_subsystem(
    unreal.EditorActorSubsystem
)

selected_actors = list(
    actor_subsystem.get_selected_level_actors()
)

if not selected_actors:
    raise RuntimeError(
        "No actors are selected.\n"
        "Select one or more Landscape actors in the Outliner, "
        "then run the script again."
    )


invalid_actors = [
    actor
    for actor in selected_actors
    if not is_landscape_actor(actor)
]

if invalid_actors:
    invalid_actor_list = "\n".join(
        f"  - {describe_actor(actor)}"
        for actor in invalid_actors
    )

    raise RuntimeError(
        "The selection contains non-Landscape actors.\n"
        "The operation was cancelled to prevent accidental changes.\n\n"
        f"{invalid_actor_list}"
    )


with unreal.ScopedEditorTransaction(
    "Set Selected Landscape Maximum LOD Level"
):
    for actor in selected_actors:
        actor.modify()

        old_value = actor.get_editor_property(
            "max_lod_level"
        )

        actor.set_editor_property(
            "max_lod_level",
            MAX_LOD_LEVEL,
        )

        actual_value = actor.get_editor_property(
            "max_lod_level"
        )

        unreal.log(
            "[SelectedLandscapeLOD] Success: "
            f"{describe_actor(actor)}: "
            f"max_lod_level {old_value} -> {actual_value}"
        )


unreal.log(
    "[SelectedLandscapeLOD] Completed. "
    "Press Ctrl+S to save or Ctrl+Z to undo."
)

To restore the default automatic LOD behavior, change:

MAX_LOD_LEVEL = -1

Notes

Forcing LOD 0 may increase rendering cost, particularly on large Landscapes. Performance should be tested on all target platforms.

I also tested the following hidden Landscape properties:

  • lod0_screen_size
  • lod0_distribution_setting
  • lod_distribution_setting
  • lod_blend_range

These properties produced IllegalPropertyOverride validation errors in my project, so they are intentionally not included in the script above.

In my test, max_lod_level did not appear in that validation error list.