Raster Calculator ArcGIS Pro Guide
A raster calculator supports map algebra before you commit work to a full spatial model. This page focuses on single cell math, spectral indices, reclassification, conditional logic, slope checks, and weighted overlay scoring. It is not a replacement for a spatial analyst workflow. It is a planning aid for testing values, units, and equations.
Why Cell Math Matters
Raster tools work cell by cell. Each output cell comes from one or more input cells. When a formula is wrong, the error can spread across thousands of cells. A small testing form helps you verify signs, thresholds, scale factors, offsets, and NoData rules. You can also compare expected classes before building a model.
Key Operations
NDVI, NDBI, and NDWI use normalized difference formulas. They return values from about negative one to positive one when inputs are valid. Weighted overlay combines several bands or criteria with chosen weights. Reclassification converts continuous values into simple classes. Conditional logic writes one value when a test is true and another when it is false. Slope estimation uses a three by three elevation window and cell size.
Good Input Practice
Use reflectance values that share the same scale. Do not mix raw digital numbers with corrected reflectance unless that is intended. Keep all weights in the same logic. A weight of ten should mean twice as much as five. Enter a NoData value when a missing cell should stop the calculation. Use threshold fields for reclassification and conditional checks.
Reading the Result
The result panel shows the selected operation, final cell value, and supporting notes. It also displays intermediate values when they help explain the output. These details make review easier. They are useful when a team needs a compact record of assumptions. CSV export works for spreadsheet review. PDF export gives a simple calculation note for reports.
Using With Mapping Workflows
After testing values here, copy the verified formula into your mapping environment. Then run it on full raster datasets. Review statistics and sample points after processing. Always validate outputs against field knowledge, metadata, and projection details.
Advanced Checks
Advanced checks should include units, resampling method, pixel alignment, and band order. Document these choices so later edits remain traceable for every map.