Click the Set Operation Expression button in the Algebraic Operations window to enter the Raster Algebraic Operation Expression dialog.
In the Raster Algebraic Operation Expression dialog, you can semi-automatically input operation expressions. Parameter descriptions are as follows:
Workspace
The left panel lists all data sources and datasets under current workspace, displaying band information under image dataset nodes, enabling quick selection of raster datasets or bands when inputting operation expressions.
Common Functions
Common functions include Arithmetic, Trig, Exp/Log functions and Other functions. Details are explained below:
| Operation Type | Description | Illustration |
| Arithmetic Functions | abs(x) | Absolute value function |
| mod(x, y) | Modulus function returning integer remainder of x/y. When y>x, mod(x, y) = x | |
| floor(x) | Round down function returning nearest smaller integer (e.g., 1.8 → 1.0, -2.2 → -3.0) as float value | |
| Trig | sin(x) | Sine function |
| cos(x) | Cosine function | |
| tan(x) | Tangent function | |
| cot(x) | Cotangent function | |
| asin(x) | Arcsine function | |
| acos(x) | Arccosine function | |
| atan(x) | Arctangent function | |
| acot(x) | Arccotangent function | |
| sinh(x) | Hyperbolic sine function | |
| cosh(x) | Hyperbolic cosine function | |
| tanh(x) | Hyperbolic tangent function | |
| Exp/Log Functions | exp(x) | Natural exponential function |
| pow(x, y) | X raised to the power of y | |
| sqrt(x) | Square root of x | |
| ln(x) | Natural logarithm | |
| log(x) | Base-10 logarithm | |
| Other Functions | Con(x, y, z) | Conditional judgment function. If condition x is met, returns y; otherwise returns z |
| IsNull(x) | Checks if expression contains invalid values. Returns 1 if x is Null, otherwise 0 | |
| pick(n1,n2,n3,...,nn) | Updates raster values using first raster dataset's values as positions, assigns values from subsequent datasets/numbers to generate new raster dataset |
Common Operators
SuperMap provides basic arithmetic, relational and logical operators. Click operator buttons to display corresponding operators in expression dialog. Details see Common Operators
Expression Input Box
Selected datasets or operators from Workspace (double-click), Common Functions (click), and Common Operators (click) will be displayed in the expression input box.
Notes:- Dataset reference format: [DatasourceName.DatasetName], e.g., [Jingjin.BeijingTerrain]
- Arithmetic operands can be datasets or numeric constants
- Math arguments can be numbers, datasets, or operational expressions
- Negative numbers require parentheses ()
- Expression must contain at least one raster dataset
Related Topics