— Tag
#state-plane
3 posts tagged state-plane.
A Foot Is Not a Foot
For sixty-three years the United States had two feet: the international foot the rest of the country adopted in 1959, and the US survey foot that surveyors kept. They differ by two parts per million -- about an eighth of an inch per mile, which is why nobody worried. Then you put that eighth of an inch into a state-plane coordinate with seven digits in front of the decimal, and it becomes six feet. The survey foot was officially retired at the end of 2022. Your archive did not get the memo.
One Digit, Half a State
Indiana's state-plane family is four EPSG codes that sit one digit apart: 2965, 2966, 2967, 2968. Two of them differ by half a state; two of them differ by tenths of a foot. Mislabel a file with the wrong one and you get either an error so loud somebody 'fixes' it wrong, or one so quiet nobody notices until a corner will not check. Here is how the family fits together, the two ways it fails, and the ten-minute habit that catches both.
When 'State Plane' Isn't State Plane: The Custom-Scale-Factor Trap
Some surveying firms apply a custom scale factor or rotation to their state-plane work to align with a local monument. The PNEZD output looks like normal state plane to any downstream tool -- but verification points land 5 to 50 feet off. Here's how to spot it, diagnose it, and fix it.
Get new posts in your inbox
Roughly weekly. No filler. Unsubscribe with one click.