Lazily load payloads from environments

[BarceloChristian]

USD provides the notion of payloads as lazily loaded references that.
In the context of huge photo-realistic environments as the ones Isaac Sim shines the most with, having to open the scenario to then disable the payloads if needed.
Instead, adding the option to open a USD with ALL payloads disabled would improve the bring up time a lot and ease the edition of highly composited environments.

This could be added directly to Kit (or an Isaac Sim's extension) with a menu in File -> Partial Load (or any other name) triggering a piece of code similar to this:

import omni.usd
from pxr import Usd
stage_path = "/path/to/my/stage.usd"

context = omni.usd.get_context()
context.open_stage(stage_path, None, load_set=omni.usd.UsdContextInitialLoadSet.LOAD_NONE)

If we were to go even one more step forward, we could allow to select which prim paths to load or not. Even tho a little more convoluted, it may be useful

import omni.usd
from pxr import Usd

stage_path = "/path/to/my/stage.usd"
subtree_prim_path_to_keep_unloaded = "/World/heavy_tree_models"

rules = Usd.StageLoadRules()
rules.AddRule("/", Usd.StageLoadRules.AllRule) # Load all!
rules.AddRule(subtree_prim_path_to_keep_unloaded, Usd.StageLoadRules.NoneRule) # But not this subtree

context = omni.usd.get_context()
context.open_stage(
    stage_path, 
    load_set=omni.usd.UsdContextInitialLoadSet.LOAD_NONE
) # This opens the stage with all the payloads unloaded!

stage = context.get_stage()
stage.SetLoadRules(rules) # Set the load rules right after open_stage, it will load any payload that it should.

[lhuang-svg]

Thanks @BarceloChristian! Will bring this idea to the team!

[lhuang-svg]

Opened an internal ticket for this feature. Will post the ETA when it is available.

[lhuang-svg]

Thanks for the suggestion. This is already supported through File → Open: in the file picker, expand Options and uncheck Open Payloads before opening the USD stage. This opens the stage with payloads unloaded, after which payloads can be selectively loaded from the Stage window.
Since the requested workflow is already available, we’re closing this discussion. Thanks again for the feedback!