Scan Workflow

The scan workflow brings a very high-poly mesh, usually a trunk, into Natsura and prepares it for the rest of the tree. The mesh can be a photogrammetry scan (RealityCapture, Metashape), a sculpt from ZBrush or Blender, or a hand-modelled trunk. Such a mesh has no rig and nothing Natsura can grow from; the scan tools cut it into parts Natsura can use.

What you can do with a scan

• Grow from it. The scan becomes the base of the tree, and Natsura grows branches (or roots) from its open ends, with the join blended. This is the main use, covered step by step in Trunk Extension.
• Cut out regions. A knot hole, a scar or a tubular section can be cut out as its own mesh or texture.
• Extract tiling textures. A tube or a square patch of the scan becomes a tiling bark texture, for the join at the extension or for other materials. See Baking for Scans.

The tools can also remesh, reduce and UV the scan, trim parts off it, and pick which of its open ends to grow from.

Working with heavy scans

A scan can be heavy enough to slow the Houdini viewport to a crawl. The scan nodes show a point cloud, the proxy, in place of the mesh, and work on the full mesh only when they have to. You select and trim on the proxy, and the changes carry over to the mesh. Proxy Settings on Import Highpoly set how many points the proxy keeps. Proxy Reduction Mode starts on None, which keeps every point, so for a heavy scan set it to Point Spacing or Keep % of Points.

The nodes

Most of the nodes below are in the toolbar's Scans menu, and all of them are in the Tab menu.

For growing from a scan, three nodes do the work, in this order:

1. Import Highpoly loads the mesh and its textures, and lets you trim it and pick the ends to grow from. Press Enter in the viewport to be guided through it.
2. Create Graft Mesh remeshes the scan and prepares its ends for the growth to attach to.
3. Bake bakes the scan's textures onto the new mesh.

The result goes into a Trunk Decoration on a Grow.

For cut-out regions and tiling textures, Import Highpoly is followed by the smaller tools it is built from, and a few more: Scan to Parts (keep or delete regions), Scan Profiles (pick ends), Scan Material (the scan's textures), Scan Rig, Scan to Tube and Scan to Patch.

Scan or procedural trunk

A scanned trunk is worth it for hero trees and close-ups, or when the tree has to match a real one. For forests with many trees seen from a distance, a procedural trunk from a Surface Decoration costs less, and a distinctive scan repeats visibly when it's used on many trees.

The Extend Scanned Trunks video walks through the most common use, extending a scanned trunk.

Status

The scan tools are experimental. They are well tested on tube-shaped trunks and on some trunks with many open ends, but results depend on the scale and complexity of the mesh, so please tell us when something fails. Scan Rig and Scan to Tube are marked experimental; Scan Rig is only useful for making tube sections for now. Working on the full mesh only at the end is the aim, and some steps still run on it straight away.