This study introduces BRAVO (Building Regulation Answering & Visual Observation) Bench, the first benchmark designed to evaluate the capability of Multimodal Large Language Models (MLLMs) to perform compliance checking based on BIM-derived scenes. BRAVO Bench integrates 26 BIM-scenes, 59 textual normative provisions, and 5 regulatory illustrations, producing 1505 question–answer pairs across four diagnostic layers: scene perception, scene understanding, rule interpretation, and compliance reasoning. The evaluation combines conventional accuracy-based metrics for closed-form tasks, BLEU/ROUGE for generated responses, and a ground-truth-centric step-level evaluation framework for compliance reasoning. This framework measures covered, missing, split, and extra reasoning steps through human or LLM-assisted review, and aggregates them using the Compliance Reasoning Score (CRS), a non-compensatory geometric mean designed to prevent strong performance in one dimension from masking failure in another. Results reveal a substantial cognitive barrier in current state-of-the-art MLLMs. The models demonstrate high performance in scene perception, with the highest score by Gemini 3 Pro Preview reaching 92.2% accuracy in object recognition and 72,7 % in Scene Perception tasks as a whole. Performance declines sharply on ambiguous regulatory norms, where even top-tier models like Gemini 3 Pro and Claude Opus 4.6 reach overall accuracy of only 65.7% and 61.4%, respectively, requiring expert judgment and collapsing on tacit-knowledge tasks involving implicit commonsense and domain assumptions. Error analysis further identifies missing reasoning steps and weak multi-view synthesis as key failure patterns. BRAVO Bench provides a foundation for diagnosing, adapting, and retraining MLLMs for compliance-oriented reasoning in the AEC.

Repository Contents

ritanibar/BRAVO
|-- data/
|   |-- bravo_qa_pairs.csv
|   `-- bravo_qa_pairs.jsonl
`-- images/
    `-- ...

The CSV and JSONL files contain the same benchmark content in two formats. The images/ folder contains BIM scene images and, where applicable, regulatory figures referenced by dataset rows.

Data Schema

Each row represents one benchmark question. Main columns:

question_global_id: globally unique question identifier.
layer: top-level diagnostic layer (1, 2, 3).
subtask: layer-specific subtask group (for example 1_1, 1_2, 2_1, 2_2, 2_3, 3_1).
question: question/prompt text.
ground_truth: reference answer.
scene_image: image filename from images/ for scene-based questions; empty otherwise.
rule_image: image filename from images/ for rule-figure questions; empty otherwise.
rule_id: associated rule identifier when applicable.
parent_rule_id: parent rule identifier when applicable.

Diagnostic Layers

Scene Perception: low-level visual fact extraction (object presence, attributes, text in scene).
Scene Understanding: spatial and functional relationship reasoning over scene layouts.
Rule Understanding: interpretation of regulatory statements and related figures.
Compliance Reasoning: joint reasoning over scene and rules for compliance decisions.

Intended Use

BRAVO Bench is intended for evaluating MLLMs in visually grounded regulatory interpretation and BIM-scene-based compliance checking workflows in AEC settings.

Limitations

This is a research benchmark with limited coverage of scene types and regulatory sources. It should be treated as a diagnostic evaluation set, not as a complete representation of full real-world permitting workflows.

License

The BRAVO Bench dataset, including question-answer pairs, annotations, metadata, and rendered BIM scene images, is released under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA 4.0), unless otherwise stated.

Commercial use is not permitted without prior written permission.

Third-party materials (including regulatory texts, standards, and external figures) are not covered by this license and remain subject to their original terms.

Citation

Citation information will be added after publication of the associated paper.

Examples of questions and ground truth for DBP26

Scene Perception question examples

Question to Figure 4	Ground truth
Does this view contain handrails? Answer “Yes” or “No”.	Yes
The annotation in the attached view shows a dimension associated with the distance between the edge of the sink and a wall opposite to it. What numeric value is written there? Answer with digits only.	1181

Scene Understanding examples: Spatial relations and Functional grouping

Questions to Figure 5	Ground truth
Look at the attached image. Is dental waiting 1D41 directly connected to the stair? Answer “yes” or “no”. For this task, “direct connectivity” means that the two elements are reachable from one another either directly or through at most one intermediate node.	No
The attached image shows dental waiting 1D43. Does dental waiting 1D43 contain children’s play area? Answer “yes” or “no”.	Yes

Rule Understanding examples

Question

Ground truth

Transform the following regulatory provision into a numbered list of atomic, self-contained requirements:

“A safe and secure children’s play area should be provided off all main waiting areas.”

Each atomic rule must:
1. express exactly one Requirement;
2. be a complete, self-contained sentence;
3. include all context needed for compliance checking:
  - Applicability: where, when, to what, or to whom the rule applies;
  - Selection: permitted alternatives;
  - Exception: conditions overriding the main rule;
  - Definitions stated in the rule;
  - Logical connectives: AND, OR, NOT, necessary for correct interpretation.

1. The children’s play area must be located directly adjacent to, or leading off from, all main waiting areas.

2. The provided children’s play area must be designed and maintained to be both safe and secure.

This regulation is ambiguous. Which main category of ambiguity does it belong to?

Categories:
1. “Unintentional ambiguity — Use of language” appears because natural language is inherently imprecise.
2. “Unintentional ambiguity — Tacit knowledge” refers to the implicit, experience-based knowledge embedded in building requirements but not fully written down, formalized, or explicitly stated.
3. “Unintentional ambiguity — ACC-specific” applies when requirements are understandable to humans outside ACC, but become ambiguous when mapping objects or relationships in requirements to objects or relationships in the design model.

Rule: The provided children’s play area must be designed and maintained to be both safe and secure.

Choose one: 1 — Use of language, 2 — Tacit knowledge, 3 — ACC-specific, or 4 — None of them. Write only the digit and nothing else.

Tacit knowledge

Compliance examples

Question / reference

Ground truth / model response

Compliance question to Figures 3 and 4

Is the design displayed in the picture compliant with the following rule?

Rule: “The following activities take place in a semi-ambulant WC (see Figure 88): use of the toilet; disposal of sanitary towels (optional); hand-rinsing.

Emerald (Greenish) Zone: Semi-ambulant Toilet Activity Space represents the required clearance for approaching and using the semi-ambulant toilet. Low-Level Space: A clear space of 600 mm (height, width, and depth) is required in front of the toilet pan at a low level to allow for user positioning. Overall Width: The entire activity zone for the toilet should have a width of 800 mm and 600 mm depth on the upper level.

Purple (Pinkish) Zone corresponds to the activity space for using the ambulant/semi-ambulant hand-rinse basin, with distinct requirements at different heights. Low-Level Space: At a low level, a clear space with a width of 800 mm, depth of 600 mm, and height of 600 mm is required for a user to approach and stand at the basin. Higher-Level Space: For the upper body, a wider space of 1000 mm, depth of 800 mm, and height of 1200 mm is required to accommodate arm movements during washing and drying.”

Answer “yes” or “no”.

—

Scene sufficiency question to Figures 3 and 4

Do you think this scene contains sufficient information to perform compliance checking based on the following rule?

Rule: “The Purple (Pinkish) Zone is defined as the activity space required for using the hand-rinse basin. Darker shade shows low-level area. For user approach, a clear space must be provided at a low level with a width of 800 mm, a depth of 600 mm, and a height of 600 mm.”

Answer “yes” or “no”.

GT & Comment: Yes.

Functional zones are typically not explicitly labeled in drawings; however, the majority of experts agreed that the scene is sufficient for evaluation. Only one expert highlighted that there are not enough dimensions. None of the experts considered vertical height dimensions necessary. While the model’s comment appears reasonable, the expert survey did not support this conclusion.

Gemini 3.1 Pro Preview: The image is a 2D black-and-white floor plan that lacks the required “Purple (Pinkish) Zone” and darker shading mentioned in the rule. Additionally, it does not provide the vertical height dimensions needed to verify the 600 mm height requirement for the clear space.

@no

Qualitative analysis of reasoning chains

Reasoning chains to the compliance question

Ground truth reasoning chain to the compliance question

Gemini 3.1 Pro Preview

Step 1: Identify the reference standard (Figure 88)

Figure 88 shows the normative layout for a semi-ambulant WC with clearly defined activity zones:

- Emerald (Greenish) Zone for toilet use: 800 mm width × 600 mm depth at upper level, plus 600 mm × 600 mm × 600 mm clear space at low level in front of the toilet pan

- Purple (Pinkish) Zone for hand-rinse basin: 800 mm width × 600 mm depth × 600 mm height at low level, expanding to 1000 mm width × 800 mm depth × 1200 mm height at upper level.

- Minimum 900 mm circulation space for mobility aids

- A set of recommended accessories: handrails, toilet paper holder, coat hook, waste bin, paper towel dispenser, help call reset.

Step 2: Identify design elements and assess dimensional evidence in the assessed picture (Toilet 1D26)

The picture shows a toilet room (1D26) containing:

- One toilet fixture (visible on the left side)

- One hand-rinse basin (visible in the upper center area)

- Door opening inward (shown by swing arc inside the room)

- Dimensional annotations: 1118 mm (vertical between wall and basin), 974 mm (horizontal between open door and a toilet), 975 mm

- Handrails visible on the plan near the toilet

Step 3: Compare with Figure 88 (semi-ambulant WC reference).

The general arrangement (toilet and basin on adjacent walls) is relevant to Figure 88, but compliance with specific dimensional requirements must be verified. Several recommended accessories (toilet paper holder, coat hook, waste bin, help call reset) are absent, treating this as a secondary non-compliance category. Handrails: Visible on plan near toilet Paper towel dispenser: provided

Dimensional evidence assessment: The plan provides sufficient dimensional information to estimate compliance.

Step 4: Assess the Emerald (Toilet) Activity Zone compliance

Required dimensions:

Low-level: 600 mm × 600 mm × 600 mm clear space in front of toilet pan. Upper-level: 800 mm width × 600 mm depth

Assessment: The toilet is positioned on the left wall with sufficient distance from the basin (approximately 974 mm width provides adequate separation) The door opens inward, which could potentially obstruct the toilet area when opened; however, the distance between the open door and the toilet appears to be sufficient. Visual proportional analysis suggests the required 800 mm × 600 mm upper-level zone can be accommodated Low-level clearance (600 mm cube) appears achievable given room dimensions and inward door swing

Conclusion: Emerald zone is compliant based on available dimensional evidence.

Step 5: Assess the Purple (Hand-rinse Basin) Activity Zone compliance

Required dimensions:

Low-level: 800 mm width × 600 mm depth × 600 mm height. Upper-level: 1000 mm width × 800 mm depth × 1200 mm height

Assessment: Basin is centrally positioned on the upper wallwidth (974 mm) and depth (1118 mm) appear sufficient to accommodate the required activity envelope. The basin's central placement allows for the wider upper-level zone (1000 mm) without wall interference

Conclusion: Purple zone is compliant based on room dimensions and fixture positioning.

Step 6: Evaluate circulation space and potential zone conflicts

Required: 900 mm circulation space for walking stick or frame

Assessment: Central space dimensions (974 mm × 1118 mm) exceed the minimum 900 mm requirement in both directions

Conclusion: Circulation space compliant.

Step 7: Final assessment

The design shown in Toilet 1D26 is COMPLIANT with the semi-ambulant WC requirements:

The rule's core intent—ensuring adequate spatial activity zones for semi-ambulant users—is satisfied. The inward-opening door and generous room dimensions (974×1118 mm) provide sufficient space for both the Emerald and Purple zones without overlap or door conflicts. While some recommended accessories are missing, spatial compliance takes precedence over accessory completeness in determining overall rule compliance.

Answer: YES

Step-by-step reasoning

Step 1: Identify the Activity Space Requirements

According to the provided rule, specific clear activity spaces must be maintained for both the toilet and the hand-rinse basin. The toilet requires an overall activity zone width of 800 mm and a depth of 600 mm. The hand-rinse basin requires a low-level clear width of 800 mm, 400 mm on each side of its center, and a higher-level clear width of 1000 mm, 500 mm on each side of its center, to accommodate arm movements.

Step 2: Analyze the Proposed Layout

In the first picture, the toilet pan is located on the left wall, and the hand-rinse basin is located on the adjacent top wall. The two fixtures are placed relatively close to the shared top-left corner of the room.

❌ Step 3: Evaluate Spatial Interference

Because the toilet and basin are placed on adjacent walls near the same corner, their required activity spaces conflict with the physical fixtures themselves.

A standard ✅ toilet pan projects approximately 550–700 mm from the wall. For the basin to have its required 800 mm to 1000 mm of clear width, there must be 400 mm to 500 mm of unobstructed space on either side of its center. Given the visual scale, ❌ using the 975 mm door as a reference, the basin is positioned such that its required clear width on the left side is physically obstructed by the projecting toilet pan. ❌ A user standing at the basin would not have the required 1000 mm upper-body width or 800 mm lower-body width because the toilet is in the way.

❌ Step 4: Compare with Reference Figure 88

The rule explicitly references Figure 88 for a semi-ambulant WC layout. In Figure 88, the toilet is placed on the rear wall and the basin on the side wall further down the room. This specific arrangement ✅ allows the Emerald toilet activity zone and Purple basin activity zone to overlap in the empty central floor space without the physical fixtures encroaching on each other’s required clearances. The design in the first picture deviates from this functional arrangement, resulting in non-compliance.

Step 5: Final Check

The placement of the fixtures in the first picture causes ❌ the toilet pan to intrude into the mandatory clear activity width required for the hand-rinse basin. Therefore, the design does not provide the necessary unobstructed spaces defined in the rule.

❌ @NO

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