Algebraic Operation

Function Description

Algebraic Operation is to carry out Spatial Analysis on geographical features and phenomena from the perspective of algebra, that is, to carry out mathematical operations and Functions on one or more Raster Data, and multiple Raster Data operations are represented as pixel value operations at the same location.

SuperMap provides rich operation expressions. In addition to common arithmetic operations (such as addition, subtraction, multiplication, division, and rounding), it also supports user-defined expressions for grid arithmetic operations, conditional operations, logical operations, Functions (including Common Functions, Trig, etc.), and compound operations.

Function entrance

Data tab-> Data Processing-> Grid-> Algebraic Operation.
Toolbox-> Data Processing-> Grid-> Algebraic Operation.

Parameter Description

Algebraic Operation Expression: input the Algebraic Operation Expression, and the expression can be directly and manually input; You can also enter
the Raster Algebraic Operation Expression dialog box through the Set Operation Expression below the text box, and enter the expression semi-automatically according to the function wizard in the dialog box; You can also quickly enter algebraic run expressions in the Algebraic Operation dialog box using the Import Export function. The file format of the
Import Export operation expression is described as follows:
```
 <? xml version="1.0" encoding="UTF-8"?> < SmXml:MathOperation xmlns:SmXml="http://www.supermap.com/xml"> <SmXml:Expression> Con( DEM.dem > 1000,1,-9999)</SmXml:Expression>; <SmXml:PixelFormat> 6400</SmXml:PixelFormat> <SmXml:BZip> TRUE</SmXml:BZip> <SmXml:BNoValue> TRUE</SmXml:BNoValue> <SmXml:BShowProgress> TRUE</SmXml:BShowProgress> </SmXml:MathOperation>  
```
< Expression> Field is used to store Algebraic Operation Expression within the Expression dialog box.

< PixelFormat> The field represents the pixel storage type of the Result Dataset, where 1 is 1 bit, 4 is 4 bits, 8 is single byte, 16 is double byte, 320 is integer, 64 is long, 3200 is Single, and 6400 is Double.

< BZip> Indicates whether to Compress Dataset, FALSE is not to compress, and TRUE is to compress.

< BNoValue> Indicates whether to Ignore NoValue Cells, TRUE is the Ignore NoValue Cells, and FALSE is not ignored.

< BShowProgress> Indicates whether to Show Progress Bar.
Pixel Format: Set the Pixel Format of Result Dataset. Application provides 11 formats including 1 bit, 4 bits, 8 bits, 16 bits, 32 bits, 64 bits, Single and Double. For a description of each format, see the Raster Dataset Pixel Class Format .
Compress and store the Dataset: After checking this check box, the system will compress and store the Result Dataset, otherwise, it will not be compressed and stored.
Ignore NoValue Cells: After this check box is checked, the grid cell with no value in the input Raster Dataset will not participate in Algebraic Operation, and the pixel value at the corresponding position in the Result Dataset is still null (usually -9999); If this option is not checked, the pixel value of the grid cell with no value will be used as the normal pixel value in the calculation, and the minimum value (or maximum value) of the Result Raster Dataset will change. The pixel values of the cells
without values can be viewed in the properties window of the Dataset, as follows:
- Workspace Manager.
- Properties Panel.
Datasource: Select the Datasource to be saved by Result Dataset.
Dataset: Sets the name of the Result Dataset.

Environmental description

The Analysis Environment parameter can be set in the Environment section. Analysis Environment parameters supported by Raster Algebraic Operation include Geographic Range and Clip Bounds of Result Dataset. Please refer to the Set up the Analysis Environment page for detailed description.

Caution: