Any way to improve tileset subtree loading performance on deep tilesets?

[cmcnicholas]

Question

I am experiencing the browser locking up (5-6 seconds) on initialising deep tilesets. The ones I am dealing with are between 262,144 and 16,777,216 in total tiles using implicit tiles and a constant subtree (added both at the end).

Attached screenshot from perf tab:

Most of the time looks like its spent in:

• getTileBoundingVolume()
• parseImplicitUri()
• general garbage collection

I've tried tweaking .processNodeQueue max jobs down to 5 but haven't noticed any difference. I did see some PR's for progressive loading of SUBTREE which looks like its the default behaviour, just wondering if I should be doing something different to improve the load stutter.

Supplemental Data

Tileset

{
    "asset": {
        "version": "1.1"
    },
    "geometricError": 152.8740577697754,
    "root": {
        "boundingVolume": {
            "box": [
                0,
                0,
                0,
                39135.75848201024,
                0,
                0,
                0,
                39135.75848200871,
                0,
                0,
                0,
                0.001
            ]
        },
        "refine": "REPLACE",
        "geometricError": 152.8740577697754,
        "content": {
            "uri": "content/{level}_{x}_{y}.glb"
        },
        "implicitTiling": {
            "subdivisionScheme": "QUADTREE",
            "availableLevels": 12,
            "subtreeLevels": 12,
            "subtrees": {
                "uri": "dynamicsubtree.subtree"
            }
        }
    }
}

SUBTREE

{
  tileAvailability: { constant: 1 },
  contentAvailability: { constant: 1 },
  childSubtreeAvailability: { constant: 0 },
}

Library Version

0.4.18

Three.js Version

180

[gkjohnson]

I expect this is because your implicit subtree is 12 layers deep and the subtree is fully instantiated on load - that's 4**12 tiles or 16,777,216. It would likely be possible to adjust the implicit tiles such that they expand as needed (similar to quantized mesh, image tiles) but your best bet short term is probably to construct more shallow subtrees.

cc @AnthonyGlt