Description
Return floor-divided tile indexes and nonnegative modular local indexes for the supplied column and row.
A geographic grid uses indexes, tile sizes, origins, and cell spacing. Row direction and floor-division policy determine where cells fall, especially for negative indexes or origins defined at an outer corner.
Return floor-divided tile indexes and nonnegative modular local indexes for the supplied column and row.
When to use this tool
Use Geographic Grid Cell Local Index when you need an explicit grid-index or angular-resolution calculation.
How to use the tool and how it works
- Enter column, row, columnsPerTile, rowsPerTile. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read tileColumn, tileRow, localColumn, localRow. Use the output convention below.
Require positive integer columnsPerTile and rowsPerTile. Return floor-divided tile indexes and nonnegative modular local indexes for the supplied column and row.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| column | Column | Required. Safe integer. |
| row | Row | Required. Safe integer. |
| columnsPerTile | Columns Per Tile | Required. Safe integer; minimum 1. |
| rowsPerTile | Rows Per Tile | Required. Safe integer; minimum 1. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| tileColumn | Tile Column | Required. Safe integer. |
| tileRow | Tile Row | Required. Safe integer. |
| localColumn | Local Column | Required. Safe integer. |
| localRow | Local Row | Required. Safe integer. |
{
"input": {
"column": -1,
"row": 9,
"columnsPerTile": 4,
"rowsPerTile": 4
},
"output": {
"tileColumn": -1,
"tileRow": 2,
"localColumn": 3,
"localRow": 1
}
}Limitations and assumptions
- Negative global indexes map to negative tiles with nonnegative local positions. Tile sizes are cell counts; geographic coordinates, raster bounds, and physical cell dimensions are not used.
- 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
Use the raster's actual georeferencing transform for geographic placement. Verify corner versus center origin, axis direction, tile dimensions, and bounds before combining index calculations.
References
Similar or alternative tools
- Map Grid Cell Origin Sign
Offset the origin by column plus one half horizontally and signed row plus one half vertically.
- Geographic Graticule Label Step
Require positive stepDegrees and return originDegrees plus index times stepDegrees.