• Each assumption reduces some risks and increases others.
• Proceeding without review is still a decision.
• Verify against Canon before professional use.
ⓘ Assumption history resets when session ends.
Decision Dependency Notice
Previous coordinate decisions are not available in this session. Consistency with prior coordinate
assumptions cannot be guaranteed.
Risk Priority Conflict
• Risk priorities depend on intended use.
• Reducing one risk may increase another.
• No single risk resolution path exists.
Selection does not remove risk or provide recommendations.
High-Assumption Context Detected
You are operating in a high-assumption context. For surveying, legal, or construction use, independent
verification is required.
Coordinate transformation is a mathematical act; boundary determination is a professional act.
Before using result data for legal, construction, or life-safety tasks:
Reference scenarios analyzing the downstream impact of coordinate errors (Datum shifts, Projection misuse) on
professional liability and project costs.
The 1-2 Meter (3-6 Foot) NAD83 Shift: Because the North American
Plate drifts, WGS84 and NAD83(2011) are currently out of sync by up to 2 meters in the conterminous US. Mixing
these datums in construction or boundary litigation is catastrophic. Understand
the precise offset mechanics.
What is the MGRS precision level equivalent to distance?
MGRS precision depends on the
digits after the 100km identifier: 10-digit (1 meter), 8-digit (10 meters), 6-digit (100 meters), and
4-digit (1,000 meters). True positional accuracy depends entirely on your initial GPS geometry collection.
Is UTM or State Plane Coordinate System (SPCS) more accurate?
SPCS zones are designed per
state and minimize scale distortion (often 1:10,000) for a smaller confined footprint. UTM covers 6-degree
global bands resulting in greater stretch (around 1:2,500). SPCS is highly preferred for US construction
and cadastral surveys.
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専門的な測地基準に準拠して検証済み
The $50,000 Geodetic Drift Liability: NAD83 vs WGS84