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bonsai-impl-qto

Compute IFC quantity takeoffs from Blender mesh geometry and IFC metadata.

30|4|Updated Mar 5, 2026
Search Tags:#blender#ifcopenshell#bonsai#qto#bim automation#ifc quantity takeoff#gross vs net
One-click install
npx skills add https://github.com/Impertio-Studio/Blender-Bonsai-ifcOpenshell-Sverchok-Claude-Skill-Package --skill bonsai-impl-qto-impertio-studio
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: bonsai-impl-qto
Source: https://github.com/Impertio-Studio/Blender-Bonsai-ifcOpenshell-Sverchok-Claude-Skill-Package/tree/main/skills/bonsai/impl/bonsai-impl-qto
Command: npx skills add https://github.com/Impertio-Studio/Blender-Bonsai-ifcOpenshell-Sverchok-Claude-Skill-Package --skill bonsai-impl-qto-impertio-studio

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

Bonsai QTO (quantity takeoff) often fails or produces incorrect results when quantities are computed manually or with the wrong gross/net assumptions, missing IFC classification, or missing material density for weights.

Core Features & Use Cases

  • Automated base quantities from geometry: Use Bonsai QtoCalculator-style logic to derive area, length, volume, and weight quantities from mesh/IFC-backed elements instead of ad-hoc calculations.
  • Gross vs net quantity correctness: Ensures the right variant is used for elements with openings (doors/windows), preventing over/underestimation in cost and material workflows.
  • Batch and single-quantity workflows: Supports targeted single calculations and rule-driven batch QTO using JSON mapping between IFC classes (IfcWall, IfcSlab, IfcColumn, etc.) and calculator functions.

Quick Start

In your Bonsai-enabled Blender session, select the target mesh objects with valid IFC class assignments and run quantity takeoff for the appropriate rule (for example, Wall base quantities) so the skill computes and writes the corresponding IfcElementQuantity values.

Frequently Asked Questions about bonsai-impl-qto

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I calculate IFC quantity takeoff in Bonsai directly from mesh geometry?▼

To perform IFC quantity takeoff in Bonsai, select mesh objects with valid IFC class assignments and run the appropriate QTO rule. The skill uses bonsai.bim.module.qto operators to compute and write IfcElementQuantity values directly from mesh geometry.

Why does my Bonsai QTO return incorrect volumes for walls with door openings?▼

Incorrect Bonsai QTO volumes occur when wrong gross/net variants are applied to elements with openings. Selecting the correct net or gross variant in the QTO calculator prevents overestimation and underestimation in cost and material workflows.

How do I set up batch rule-based IFC quantity takeoff for multiple building elements?▼

Batch rule-based IFC quantity takeoff uses JSON mapping between IFC classes like IfcWall or IfcSlab and calculator functions. This configuration drives the Bonsai QTO operators to process multiple elements simultaneously based on IFC classification.

Do I need to configure material density for IFC weight calculations in Bonsai?▼

You must set Pset_MaterialCommon.MassDensity before executing weight calculations in Bonsai. Without this material property configured, the Bonsai QTO calculator cannot accurately derive weight quantities from the mesh volume.

What IFC classes are supported by the Bonsai QTO calculator for base quantities?▼

The Bonsai QTO calculator supports base quantities for walls, slabs, columns, beams, spaces, roofs, doors, windows, and stairs. It matches QTO set names to these specific IFC classes to ensure accurate area, length, volume, and weight computations.

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