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Batch V‑Ray proxies and Arnold standins for an asset library

To populate a large scene, a .vrmesh proxy or an .ass standin keeps the geometry in a file that the renderer reads at render time, without unpacking it into the scene. Making them by hand means opening each asset, giving it back its materials and running an export. Everything, the CGfield conversion application, writes these files for every asset in the queue, next to its other deliverables.

What each file contains

The .vrmesh is written by ply2vrmesh, the conversion tool that ships with V‑Ray. Everything feeds it a temporary Alembic split into one shape per material, named after it: the proxy therefore carries the geometry, its UVs and one shader set per material, and V‑Ray finds the materials by name at render time. It holds no shader network and no texture path. Its preview, what the 3D view shows, is reduced to 40,000 faces at most; a lighter asset keeps its whole mesh.

The .ass is exported by the Houdini Arnold ROP. It contains the geometry, the Arnold shaders and their per-face assignment, and nothing else: no light, camera or render setting from the conversion scene. Textures are referenced in it by absolute paths, because the file is read from another scene, in another folder.

Steps

  1. Install the CGfield launcher with a free account, then Everything.
  2. Drop your asset folders into Everything, or choose several at once: each one takes its place in the queue.
  3. In the Delivery section, leave “USD component” off and tick .vrmesh, .ass or both among the formats. Ticking .vrmesh turns on the V‑Ray engine and ticking .ass turns on Arnold, because a standin is read and shaded by its own renderer only.
  4. To get the native scenes as well, keep .abc ticked: a native scene cannot be built on a standin.
  5. Choose the output folder and start the export: each asset folder receives its .vrmesh and its .ass, next to materials.json, the textures folder and the thumbnail.

What Everything checks in each file

After writing, Everything reads each standin back. The .vrmesh goes through ply2vrmesh -info, which counts its UV sets and shader sets; the .ass is read to find the geometry, Arnold surfaces and textures that exist on disk. A file that lost what the source geometry carried is delivered with a warning shown in Everything; an unreadable file is not delivered. On some assets ply2vrmesh fails: Everything then tries a second route, then the Houdini V‑Ray ROP, which writes the geometry as a single object, without material names. The .vrmesh is then delivered with a warning, and the Alembic remains the route for textured rendering.

Placing them in Houdini, Maya and 3ds Max

In the AssetBrowser app, the geometry format is set per application: choose V‑Ray Proxy or Arnold Standin. The panel then only shows the assets that deliver that format, and an asset dragged into the scene arrives as a standin. A standin set for the other renderer is never placed: the drop uses the Automatic format and the panel says so.

For the .vrmesh, Everything builds the V‑Ray materials from materials.json and the delivered textures, and assigns them shader set by shader set, using the names read in the file; the .ass arrives with its own shaders. In Houdini the .ass becomes an Arnold procedural object, to drop into /obj or the 3D view, because dropped into a SOP network it only gives a preview; the .vrmesh becomes a V‑Ray proxy node in SOPs. Maya places an aiStandIn displayed shaded or a V‑Ray proxy; 3ds Max places an Arnold Procedural Object or a V‑Ray proxy with a Multimaterial, both turned upright for its Z axis. If a .vrmesh carries no shader set while the asset has several materials, no material is assigned rather than one painted over the whole asset, and the drop message says so.

Good to know

Everything runs on 64-bit Windows 10 and 11. The standins are written by Houdini 20.5 or later: Everything uses the most recent version where Arnold or V‑Ray is installed. The .ass needs Arnold for Houdini (HtoA) and the .vrmesh needs V‑Ray or its ply2vrmesh tool on the converting machine; without them the file is not written. To place and render them, each application needs the standin’s renderer; AssetBrowser does not place them in Blender. A standin does not replace the geometry of a scene. The free account includes one trial export and each asset written counts as one export: a whole library needs a paid plan.

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