A colleague sent me two folders last month. One held a GLB exported from Meshy, a bench with a nice wood texture. The other held a site export from GenAnywhere covering the plaza where the bench was supposed to go. His question was short: make these line up.
They do not share a coordinate system, a unit convention, or a lighting model. That is not a defect. The two tools are built for different scales, and the integration work is the same every time. It belongs in the asset pipeline, not in someone's memory. Any 3D pipeline that mixes generated assets with generated sites hits it.
The two outputs

Meshy: assets

Text or image in, mesh out. You get a GLB (glTF) or FBX with PBR maps, several variants, and options to re-mesh or retopologize. Pivots usually sit near the object center, and the exporter assumes meters. The unit is a convention, not a guarantee.

GenAnywhere: sites

A map selection returns a stage set: ground, building blocks, trees, and pavement in a viewer. Coordinates are local to the generated block, and the ground plane is the reference everything else sits on. Vegetation and buildings are context, not measured geometry.
The export is not GIS data. Parcel lines, utilities, and elevations come from other sources and still need checking. Treat the block as a stage set: good for placement and camera work, not for quantities.

Check one: units

Import both into the same scene and measure something you can recognize. A door, a curb height, a parking stall. I use a 2.4-meter door because it is easy to spot. If the bench comes in at 0.4 meters, the export scale is wrong, not the model. Coordinate systems are the next check: the site block keeps its map origin, while props arrive at a local origin that means nothing until you place them.

Check two: pivots and origins

A Meshy mesh often has its pivot at the geometric center, which means placing it at ground level buries half the object. Offset by the bounding box height, or move the pivot in your DCC tool before export. Do this before you instance anything, or you will repeat the fix twenty times.

Check three: materials

PBR materials keep their roughness and metalness values in the GLB. The site viewer may not use them. A bench that looks correct in a physically based renderer can look chalky in a flat-lit viewer, and the fix is usually roughness up, metalness down. Take a screenshot in both and compare before you call it done.

Check four: topology budget

Meshy output is dense. A rock can arrive with more triangles than the entire site block. Decimate props to a few thousand triangles, reuse one mesh for repeated rocks, and keep the high-poly version in a separate folder for close-ups. Instancing beats unique meshes every time. Mesh optimization is not a polish step; it is what keeps the viewer responsive.

A small validation script

I keep a throwaway script that loads each GLB and prints its bounds and triangle count. It catches scale errors faster than opening a viewer.

from trimesh import load

If the extents do not match the intended size, stop. Scaling a wrong mesh to fit a doorway hides the error until someone measures the real object.

Naming and versioning

Site exports name tiles by coordinate. Meshy names files by prompt, which is useless three weeks later. Rename each asset by location and function: plaza-bench-north, kiosk-trailhead, culvert-headwall. Keep the source prompt in a text file next to the asset. When a reviewer asks for a taller backrest, you will want the prompt, not a guess.

Rendering and handoff

The end use decides how much cleanup is worth doing. For a 3D visualization that only needs silhouette and material, decimation and a flat lighting check are enough. For digital twins, provenance matters as much as geometry: which surfaces were generated, which were measured, and ## who touched them last.
Keep the scene graph simple. One parent for the site, one for props, one for lights. Technical art is mostly naming and hierarchy, and a clean hierarchy makes model validation possible later. If every asset sits loose in the root, nobody can audit the file.

When not to mix

If the deliverable is a construction model, generated site geometry is context only. Do not derive quantities from it. Use the asset models for visualization, keep the measured surface for design, and label which is which in the file. The pipeline is only as trustworthy as its weakest input.