User Guide

Numbered callout markers and leader lines for technical Blender scenes. This guide covers installation, day-to-day usage, and known limits.

What's in the package

• explocallout.blend — the asset file. It contains one asset: the TO_Callouts Geometry Nodes node group (marked in the Asset Browser under the "Callouts" catalog), plus a small example assembly scene with callouts already applied so you can see the result before touching anything.
• blender_assets.cats.txt — the asset catalog definition. Keep it in the same folder as the .blend file so Blender's Asset Browser can read it.
• This guide, plus the store listing copy for reference.

See Compatibility for the supported Blender versions.

Installation

You have two options — pick whichever fits your workflow.

Option A — Add as an Asset Library (recommended)

1. Put the .blend file (and blender_assets.cats.txt) in a folder you control, e.g. Documents/BlenderAssets/ExploCallout/.
2. In Blender, open Edit > Preferences > File Paths > Asset Libraries and click + to add a new library pointing at that folder.
3. Open the Asset Browser in any 3D Viewport (the icon in the top-left of the editor type dropdown), pick your new library, and you'll see the TO_Callouts node group under the Callouts catalog (that's the asset's technical/internal name — it's what the Asset Browser tile shows, distinct from the "ExploCallout" product name on this guide's cover).
4. Drag the node group onto any mesh object in your scene, or use the Add > Node Group menu inside a Geometry Nodes modifier.

Option B — Append or Link directly

1. In the file you're working on, go to File > Append (or Link if you want to keep the asset updated from the source file), navigate into explocallout.blend > NodeTree, and select TO_Callouts.
2. The node group is now available in your file's Geometry Nodes modifier node group picker.

Append copies the node group into your file (safe, self-contained). Link keeps a live reference to the original .blend file (useful if you want updates to the node group to propagate automatically, but the original file must stay reachable at its path).

How it works — the short version

TO_Callouts takes a cloud of anchor points (one per part you want to label) and, for each anchor, generates:

• a small marker (an icosphere) at the anchor position, and
• a leader line running from the anchor out to a label position.

It expects a label_offset vector attribute on those points — a vector from the anchor to where you want the label to sit. You build that point cloud yourself: one Mesh object where each vertex sits at a part's world-space origin (a good name is Callout_Anchors, matching the example scene), with a Float Vector attribute named label_offset per point, then TO_Callouts applied to it as a Geometry Nodes modifier. The numbered text objects and their camera-facing constraint are also a manual step you set up per scene — the node group itself only draws the marker and leader line from the anchors you give it.

The recommended workflow:

1. Duplicate the example scene's anchor point object as a starting template (Object > Duplicate), or start from scratch with a single vertex per part.
2. Keep this points object's own transform at the default — Location (0, 0, 0), Rotation 0, Scale 1 (Object > Apply > All Transforms if you moved it). Mesh vertex coordinates are always in the object's local space; with an identity transform, local space and world space line up, so a vertex placed at a part's world position (snap to origin, Shift+S > Selection to Cursor with the 3D cursor at the part's origin) is stored correctly. If you ever give this object its own location/rotation, you'll need to place vertices in its local space instead, not world space — easiest to just leave the transform at default and avoid the conversion entirely.
3. Add a label_offset attribute: Properties editor > Object Data Properties (the green triangle-mesh icon) > Geometry Data > Attributes > +, set Name to label_offset, Type to Vector, Domain to Point. Then set each point's actual value in the Spreadsheet Editor (switch an editor to Spreadsheet, select the object, pick the label_offset column, edit each row) — a vector pointing away from the part center toward where you want its number to sit.
4. Add the TO_Callouts node group as a Geometry Nodes modifier on that points object, and adjust Marker Radius / Leader Radius to match your scene scale.
5. Add a numbered text object (Text object, Add > Text) at each label position, with a Track To constraint pointing at your camera, so labels always face it.

The bundled example scene shows this end-to-end for a 6-piece mounting bracket assembly — open it, select the objects, and inspect the modifier stack and the anchor points object to see a working reference.

Presets and framing

The example scene demonstrates a 3/4 hero angle camera. There is no built-in "preset picker" operator in this version — camera framing is a manual step, same as any other camera placement in Blender. As a starting point, three angles work well with a ring-style callout layout (avoiding a flat profile view, which tends to compress leader lines and cause label overlap):

• Hero 3/4 — classic three-quarter product angle, moderate elevation.
• Overhead 3/4 — steep top-down angle, good for flat/plan-style parts.
• Flank 3/4 — three-quarter from the opposite side, same elevation as hero (useful when the hero angle occludes a part you need visible).

For output framing, both 16:9 (landscape, e.g. video/slides) and 9:16 (portrait, e.g. social/vertical video) work well with this node group — keep at least a 5% margin from the frame edges for both geometry and labels so nothing gets clipped at render time.

Known limits (honest, not marketing)

• Readability depends on your own label layout — there's a practical ceiling. The node group itself draws markers and leader lines correctly regardless of anchor count — we verified that up to 50 anchors with no geometry issues during development. But since you choose where each label sits (the label_offset per anchor, see "How it works" above), the real-world ceiling is about how tightly your own layout packs leader lines, not something the node group manages for you. As a rule of thumb, once more than about 20 leader lines converge on a small assembly, visually tracing "which line goes to which part" gets hard for a human viewer even if nothing technically overlaps. For larger assemblies, consider labeling in groups/zones rather than one single dense cluster.
• No flat "profile" camera preset. A near-0-degree elevation angle flattens the ring layout into a near-straight line and risks label collisions — stick to a 3/4-style angle (see above). A future update may add a dedicated safeguard for this case.
• The numbered text is regular Blender text objects, not procedural Geometry Nodes text. This is intentional — it keeps text billboarding and inspection simple and reliable. It also means duplicating/renumbering labels is a manual step (or your own script) rather than automatic.
• File formats. The package ships as a native .blend asset. Export to .glb/.gltf/.fbx from your own project after applying the modifier (Convert to Mesh first, since exporters don't always preserve live Geometry Nodes modifiers) — not a distributed conversion step in this version.

Troubleshooting

A part doesn't get a callout, or labels overlap in my scene. Double-check that (a) the part is a mesh with a real vertex at its intended anchor world position, and (b) your label_offset vector isn't pointing toward another part's label position. The example scene is the reference for a known-good setup.

For anything not covered here, see FAQ or Contact / Help.