Intel Moore House: USD material network setup errors

[matthewlow-dwa]

In the most recent release of USD (v0.25.08), new warnings and errors from the Hydra framework reveal shading network setup errors. In particular, the UsdPreviewSurface materials systematically connect the rgb output of the UVTextureReader to a single-channel input. These errors ultimately cause failures in the USD Performance Metrics framework: https://openusd.org/release/ref_performance_metrics.html#moore-lane

For example in Storm:

Warning: in _MakeParamsForInputParameter at line 996 of pxr/imaging/hdSt/materialNetwork.cpp -- Unrecognized connected node: 
...

More errors should be reproducible rendering with hdPrman (or other OSL-consuming renderers), although I am not able to do so at the moment.

Additionally, there are a number of places where MaterialBindingAPI is expected to be applied, but it is currently not.

[tgvarik]

I can add a bit of additional info here.

1. The "Unrecognized connected node" error seems to be coming from </materials/willowBranch_mtl/Substance_long7/switchMtl_undefined> and <../switchNrm_undefined>, both of which look like they intended to provide custom shader implementations, but have empty sourceAsset paths. I suspect there were supposed to be additional nodes that connected into these, too, but those nodes are absent.
2. The most frequent error, which can be observed by trying to render the scene with hdPrman, is that many of the materials that use a connection into roughness, metallic, displacement, and in one case clearcoatRoughness (all of which are float) are connected to vector3f outputs. In the case of displacement, it looks like these were intended to be connected to UsdPreviewSurface's normal input instead. The others connect the float inputs to UsdUVTexture's vector3f outputs:rgb (sometimes via an intermediary), and probably intended to connect to the float outputs:r (or g or b, or maybe a) output instead. This affects most, but interestingly not all, materials that use connections into these float parameters.
3. The texture asset for </materials/dirt_mtl/armChairWood_diff2> (textures/surfaces/stone sandstone 02_s100 (g010).png) is missing from the download bundle. It also has spaces in the filename (represented by + in the .usda), which is a bit risky for cross-platform support, and might be related to why the asset didn't make it into the bundle.
4. </ROOT/instances/trees_cedar/Prototypes/INST_pineTree_A/mtl_instLocal/basicLeaf_mtl/spruceNeedle_surface.inputs:baseNormal_texture> and <../spruceNeedle_preview_texture_normal.inputs:file> both have the wrong asset path. Starts with ../textures/PlantLibrary but should start with ../textures/Plants/PlantLibrary.
5. There are a bunch of nans in </ROOT/Living/Props_sitting/CoffeeTableGrp/geo/CoffeeTableProps/succulentVase.normals>.

2 and 4 are easy (if tedious) to fix by editing the appropriate .usd and .usda files. The others could be worked around the same way, but not truly fixed without reference to the source scene.