Description
Return grid equal to ground times scale and correction equal to grid minus ground.
Map scale relates ground length to grid or paper length under a declared ratio. Unit conversion and projection scale are separate operations, and a nominal scale does not measure actual display or printing behavior.
Return grid equal to ground times scale and correction equal to grid minus ground.
When to use this tool
Use Cartographic Ground Grid Scale Term when you need a length conversion under a caller-supplied map-scale convention.
How to use the tool and how it works
- Enter ground, scale. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read grid, correction. Use the output convention below.
Require nonnegative ground and positive scale. Return grid equal to ground times scale and correction equal to grid minus ground.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| ground | Ground | Required. Finite number; minimum 0. |
| scale | Scale | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| grid | Grid | Required. Finite number. |
| correction | Correction | Required. Finite number. |
{
"input": {
"ground": 1000,
"scale": 0.9996
},
"output": {
"grid": 999.6,
"correction": -0.39999999999997726
}
}Limitations and assumptions
- Scale is dimensionless and lengths share units. The caller supplies the applicable combined or grid scale convention; no projection, elevation factor, or spatially varying correction is computed.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Check the map's projection, output dimensions, and final reproduction scale. Use a locally applicable scale factor when projection distortion or elevation changes the ground-to-grid relationship.
References
Similar or alternative tools
- Map Scale Bar Paper Length
Return paperMillimetres as 1000 times groundMetres divided by that denominator.
- Coordinate Rounding Ground Error Bound
Return radius times angular step divided by two as latitudeHalfwidth and multiply it by cosine latitude for longitudeHalfwidth.