MultiModalRAG: Practice of Llama 3 Fine-tuning and RAG Retrieval-Augmented Generation in the Real Estate Domain

Large language models perform well in general domains, but struggle to meet the needs of vertical domains (such as real estate) due to issues like knowledge timeliness and domain depth. The MultiModalRAG project combines Llama3 fine-tuning and RAG technology to build a professional AI Q&A system for real estate, addressing the shortcomings of general models, supporting local deployment, and providing a feasible solution for AI applications in vertical domains.

Limitations of General Models

• Insufficient knowledge timeliness (unable to grasp the latest policy trends)
• Lack of domain depth (inaccurate understanding of professional terminology)
• Hallucination issues (fabricating incorrect information)
• Cost and privacy issues (expensive API calls and data need to be sent to third parties)

Specificity of the Real Estate Domain

Involves policies and regulations (purchase restrictions, taxes, etc.), market data (housing price trends), transaction processes (buying/selling/renting), and professional knowledge (building standards/valuation). The requirements are clear and have high accuracy demands.

Fine-tuning: Injecting Domain Knowledge

• Model Selection: Llama3.2 1B Instruct (open-source and commercializable, moderate parameters, dialogue-optimized, multilingual capabilities)
• Efficient Fine-tuning: LoRA technology (only trains a small number of low-rank matrices, memory-friendly, fast training, compact model size)
• Data Preparation: Policy documents, Q&A pairs, market reports, transaction cases, etc., are cleaned into instruction formats

RAG: Connecting to Real-time Knowledge Base

• Working Principle: Indexing (document splitting + embedding vectors) → Retrieval (relevant fragments) → Generation (combining query and retrieval results)
• Knowledge Base Construction: Housing information from sources like Zillow, market analysis, policy interpretations, transaction guides (updated regularly)
• Multimodal Possibilities: Floor plan understanding, image retrieval, video tours, etc.

Advantages of Local Deployment

• Privacy protection (data not sent to the cloud)
• Controllable costs (no API fees)
• Customization (adjustable models/knowledge bases)
• Offline availability (stable response)

Complete Workflow

1. Query reception → 2. Intent recognition (understood by the fine-tuned model) → 3. Knowledge retrieval (vector database) → 4. Context integration →5. Answer generation →6. Result return

• Real Estate Agent Assistant: Quickly answer customer inquiries, recommend properties, generate market reports, assist with transaction documents
• Homebuyer Self-service Tool: 7x24 policy consultation, personalized plans, regional investment analysis, transaction guidance
• Real Estate Investment Analysis: Multi-region comparison, return calculation, risk assessment, policy early warning

Retrieval Quality Optimization

• Query rewriting, hybrid retrieval (keyword + vector), re-ranking, multi-hop retrieval

Answer Accuracy Assurance

• Citation tracing, uncertainty expression, manual review, feedback learning

Multimodal Expansion

• Image encoding, cross-modal alignment, computational efficiency optimization

Developer Insights

• Fine-tuning and RAG complement each other (fine-tuning provides domain foundation, RAG supplements real-time knowledge)
• Data quality first (cleaning and validating data is more important than model size)
• Local deployment is feasible (supported by model compression and efficient inference frameworks)

Conclusion

MultiModalRAG demonstrates an AI paradigm for vertical domains: open-source model + domain fine-tuning + RAG + local deployment, balancing capability, cost, and privacy, providing a path for AI transformation in industries like real estate. We look forward to more AI solutions for vertical domains.