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Extract structured property data from assessment card PDFs using LLM-powered text extraction

Project description

landrecords-card-reader

Extract structured property data from assessment card PDFs using LLM-powered text extraction.

Property cards (also called land cards or assessment cards) are PDF documents produced by county tax assessors.

Installation

pip install landrecords-card-reader

With optional extras:

# LangGraph wiring (only needed if you want to use the graph node)
pip install landrecords-card-reader[graph]

# Everything
pip install landrecords-card-reader[all]

System dependencies

  • Ollama running locally or on a remote host with a text model loaded (e.g. gemma4:26b-a4b-it-q8_0)
  • wkhtmltopdf for HTML→PDF conversion of property pages that aren't served as PDFs:
    # macOS
    brew install --cask wkhtmltopdf
    # Debian/Ubuntu
    sudo apt-get install wkhtmltopdf
    

OCR (docTR + PyTorch) ships as a Python dependency; the model weights (~100MB) are downloaded to ~/.cache/doctr/ on first call.

Quick start

from landrecords_card_reader import read_property_card

data, photo = read_property_card("https://example.com/card.pdf")

print(data["ownername"])    # "SMITH, JOHN A"
print(data["totalvalue"])   # 285000
print(data["parceladdr"])   # "123 MAIN ST"

# photo is raw image bytes of the first property photo, or None
if photo:
    with open("photo.jpg", "wb") as f:
        f.write(photo)

Use analyze_photo=True to send the property photo (if it exists) to the vision model, filling in missing building details (exterior walls, roof style, number of floors, etc.):

data, photo = read_property_card(url, analyze_photo=True)

If you already have the PDF bytes, pass them directly to skip the download:

data, photo = read_property_card(url, pdf_bytes=raw_bytes)

For URLs that might be HTML property report pages (e.g. Beacon, Tyler, or other county assessment sites), use read_property_card_from_url. It fetches the URL, detects whether the response is a PDF or HTML, and converts HTML pages to PDF via pdfkit (wkhtmltopdf) automatically:

from landrecords_card_reader import read_property_card_from_url

data, photo = read_property_card_from_url(
    "https://www.webgis.net/LinkedFiles/va/pulaski/pc/cards/PC17759.htm"
)

CLI

landrecords-card-reader https://example.com/card.pdf --dry-run -v

Configuration

Set via environment variables or a .env file:

Variable Default Description
CARD_READER_LLM_BASE_URL http://graybase:8000/v1 OpenAI-compatible chat-completions endpoint
CARD_READER_LLM_API_KEY dummy API key sent as Authorization: Bearer … (use any non-empty string for self-hosted servers)
CARD_READER_EXTRACTION_MODEL gemma4:26b-a4b-it-q8_0 Model for structured extraction
CARD_READER_PHOTO_CLASSIFICATION_MODEL gemma4:e2b Lightweight vision model for photo classification

Extracted fields

The extraction prompt maps over 80 property card fields including:

  • Identity: parcelid, taxacctnum, taxyear
  • Owner: ownername, owneraddr, ownercity, ownerstate, ownerzip
  • Location: parceladdr, parcelcity, parcelstate, parcelzip, legaldesc
  • Valuation: landvalue, imprvalue, totalvalue, assessedvalue, appraisedvalue
  • Building: yearbuilt, bldgsqft, bedrooms, fullbaths, halfbaths, bldgtype
  • Construction: foundation, roofcover, extwall, heating, heatfuel, cooling
  • Sale: saleamt, saledate
  • Zoning: zoningcode, zoningdesc, zoningtype

How it works

  1. Download the PDF (or accept pre-downloaded bytes)
  2. In parallel:
    • OCR every page via docTR — PDF bytes are passed straight to DocumentFile.from_pdf (rasterised internally via pypdfium2) and run through docTR's deep-learning detection + recognition models in a single batched inference call. The predictor uses assume_straight_pages=True and runs on CUDA when available
    • Extract & classify property photos — candidate images are filtered by size/aspect ratio, then sent to a vision model to keep only actual photographs (discarding sketches, floorplans, maps, etc.)
  3. Extract structured data by sending the raw OCR text to an Ollama LLM
  4. Reconcile values — verifies landvalue + imprvalue == totalvalue and computes any single missing value arithmetically
  5. Targeted retries — if parcelid is too short, re-asks; if a heat-fuel label is present but heatfuel is empty, runs a deterministic regex fallback then a focused LLM retry; if any registered field's label is in the OCR text but the value is empty, batches them into one LLM retry

License

MIT

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