Common expressions are a list of standard mathematical and logical expressions.
| Name | Description | Expression |
|---|---|---|
| Add two inputs | Calculate sum of two inputs. | Input_1+Input_2 |
| Subtract two inputs | Calculate difference between two inputs. | Input_1-Input_2 |
| Multiply two inputs | Calculate product of two inputs. | Input_1*Input_2 |
| Divide two inputs | Calculate division of two inputs. | Input_1/Input_2 |
| Average two inputs | Calculate average of two inputs. | (Input_1+Input_2)/2 |
| Keep if < variable | Keep values from first raster if it is less than the value assigned to the variable. | Cond(Input_1 < Variable_1, Input_1, null) |
| Keep if > variable | Keep values from first raster if it is greater than the value assigned to the variable. | Cond(Input_1 > Variable_1, Input_1, null) |
| Scale range 0-255 | Scale values in input raster to range 0-255. | Round(255 * (Input_1-Rmin(Input_1))/(Rmax(Input_1)-Rmin(Input_1)),1) |
| Absolute difference of two inputs | Calculate absolute difference of two input rasters. | Abs(Input_1-Input_2) |
| Equal to variable | Extract cells that are equal to a given value. | Cond(Input_1=variable1, Input_1, NULL) |
| Not equal NULL | Extract cells that do not have NULL value. | Cond(Input_1 <> NULL, Input_1, NULL) |
| Keep first if second valid | Retain value from first raster if the second raster cell is valid. | Cond(Input_2 <> NULL, Input_1, NULL) |
| Keep first if < second | Keep value of first raster if it is less than the values of second raster. | Cond(Input_1 < Input_2, Input_1, NULL) |
| Keep first if > second | Keep value of first raster if it is greater than the values of second raster. | Cond(Input_1 > Input_2, Input_1, NULL) |
| Keep first if second equal to variable | Keep value from first raster if second raster equal to variable. | Cond(Input_2=variable1, Input_1, NULL) |
| Keep between two variables | Keep value from raster if between two variables. | Cond ((Input_1 > variable1) AND (Input_1 < variable2), Input_1, NULL) |
| Replace with variable | Replace all values in a raster equal to variable. | Cond(Input_1=variable1, variable2, Input_1) |
| Calculate NDVI | Used for remote sensing of vegetation. It calculates NDVI (Normalized Difference Vegetation Index). NDVI can be derived from digital CIR data, which can be used in plant analysis. | (NIR - Red) / (NIR + Red) where NIR is the Near Infrared channel, and Red is the Red channel. |
| Calculate NDWI | Used for remote sensing of water. It calculates NDWI (Normalized Difference Water Index). | (Green - NIR) / (Green + NIR), where NIR is the Near Infrared channel, and Green is the Green channel. |
| Calculate NBR | Used to quantitatively identify burned areas. NBR (Normalized Burn Ratio). | (SWIR - NIR) / (SWIR + NIR) |