測地学における言語モデルの技術的限界
Large Language Models are exceptional at summarizing text, but they are fundamentally unsafe for computing coordinate transformations. The reasons are rooted in the mathematics of modern geodesy.
1. Grid-Shift Models Require Interpolation, Not Recall
Modern legal datums (such as NAD83 in the US, OSGB36 in the UK, and RDNAPTRANS in the Netherlands) do not use simple mathematical formulas for transformation. They use grid-shift files (like NTv2 or NADCON5). These are massive datasets containing correction vectors for millions of specific geographic cells.
To convert a coordinate, software must look up the four nearest grid cells and perform a bilinear interpolation. A language model cannot execute spatial interpolation against a gigabyte-sized grid file; it will attempt to substitute a generic, less-accurate "Helmert 7-parameter" formula, introducing errors of up to 3 meters.
2. Epoch and Plate Tectonic Tracking
Coordinates are 4-dimensional. A coordinate in WGS84 from 1995 is in a physically different location than the same coordinate measured in 2025 due to tectonic plate motion. Transformation requires tracking the exact epoch (realization year) of the data. Conversational engines frequently blend parameters from different epochs, corrupting the positional accuracy.
3. Hallucination of Parameters
Even for simple Helmert transformations, the parameters (ΔX, ΔY, ΔZ, Rotations, Scale) require 10-decimal precision. Language models frequently substitute or transpose these extremely sensitive numbers. Changing a rotation parameter from 1.05 seconds to 1.50 seconds shifts the result by hundreds of meters.
Conclusion
Professional datum conversions must only be performed using authoritative geodetic engines (like PROJ, NGS NCAT, or validated calculators) that utilize the official national grid shift binary files. Relying on an unvalidated chatbot for coordinate conversions is a severe breach of engineering standard of care.