Instructions for use

An Algebraic Operation is a mathematical operation and Function on one or more Voxel Grid data. The voxel value of Result Data obtained by simultaneous operation is obtained from the voxel value of the same position of one or more Input Data: through Algebraic Operation.

In Order to better implement the voxel Raster Algebraic Operation function, SuperMap provides rich operators, functions, and operation expressions. In addition to common arithmetic operations (such as addition, subtraction, multiplication, division, and rounding), it also supports expressions through User Custom. To perform arithmetic operations, conditional operations, logical operations, Functions (including Common Functions, Trig, etc.), and compound operations on the Voxel Grid. A variety of voxel Raster Analysis requirements can be met through the voxel Raster Algebraic Operation.

Operation steps

1. On the 3D Data tab, in the 3D Field Data group, in the Voxel Grid drop-down menu, click the Algebraic Operation button to bring up the Voxel Raster Algebraic Operation "dialog box.
2. After setting the Parameters, click OK to execute the voxel Raster Algebraic Operation.

Parameter Description

1. Set Algebraic Operation Expression: Different types of Algebraic Operation Expression (including Dataset, number, constant, operator, function, etc.) Will be displayed in different Font styles in the expression dialog box. And is convenient for a us to distinguish.
2. In addition, in the expression dialog box, you can edit the existing expression by clicking the right mouse button and selecting relevant editing options (including Cut, Copy, Paste, Clear Expression, etc.) In the pop-up Context Menu. You can also use Windows shortcuts such as Ctrl + X, Ctrl + C, Ctrl + V, Delete, and so on. When editing Algebraic Operation Expression, it is recommended that users edit an expression as a whole so that their unique Font style is preserved. The composition of the
3. Algebraic Operation Expression shall comply with the following rules:
   When a voxel Raster Dataset is
   • referenced as an operation operand, the format is Datasource name.Dataset name, For example, the reference to VolumnDataset in the Datasource BeijingDEM is: JingjinDEM. Volumn.
   The operand of an
   • arithmetic operator can be a Dataset, a number, or a constant (such as the result of a Function over a numeric value).
   The argument of
   • Math can be a numeric value, a Dataset, or the operation expression of a Dataset or multiple Datasets.
   Parentheses () are used
   • when negative numbers are used as operands.
   • The expression must contain at least one input voxel Raster Dataset.
4. Common Functions

   In addition to common operators, SuperMap also provides 21 common functions, including arithmetic operation function, Trig, Exp/Log function and other functions. The contents of each function will be described in detail below.

   Common FunctionsInstructions for use
   Type of Function Square root

   operation	Explain	Illustration
   Arithmetic function	abs(x)	Absolute value function.
   	mod(x, y)	The modulo function, which finds the remainder of X/y, has an integer value as its output. When y & gt; X, mod (X, y) = X.
   	floor(x)	The RoundDown function, which gets the smaller integer nearest to X (for example, 1.8 is rounded down to 1.0, and -2.2 is rounded down to -3.0), outputs a floating-point 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)	The hyperbolic tangent function
   Exp/Log function	exp(x)	with the natural logarithm e as a power.
   	pow(x, y)	X to the y-th power.
   	sqrt(x)	of X.
   	ln(x)	Take the natural logarithm.
   	log(x)	Take the base 10 logarithm.
   Other functions	Con(x, y, z)	Conditional judgment function. X is the conditional expression (or value), and y and Z are the extracted values. If the function satisfies the condition X, the y value is extracted, otherwise the Z value is extracted.
   	IsNull(x)	Check whether the expression contains an invalid value. If X is Null (that is, an invalid value), the return value is 1. Otherwise, the return value is 0.
   	pick(n1,n2,n3,..., nn)	Update the Voxel Grid value. The voxel value of the specified first voxel Raster Dataset is used as the corresponding position, and the voxel of the corresponding position is assigned according to the voxel value of the subsequently input voxel Raster Dataset or the input numerical value, and finally a new voxel Raster Dataset is generated.

5. Common Operators Common Operators provided

   by SuperMap include basic arithmetic operators, relational operators and logical operators, as shown in the following figure. Click the button where the operator is located to display the corresponding Operator in the upper expression dialog box.

   Arithmetic Operations

   Common arithmetic operations include addition (+), subtraction (-), multiplication (*), and division (/). The following table details how each operation is used in Raster Algebraic Operation.

   Arithmetic operators Instructions for use.
   Type of Addition The subtraction in Multiplication in Division in

   operation	Explain
   Addition	in voxel Raster Algebraic Operation is the process of adding the voxel values in the Raster Dataset of two input voxels, voxel by voxel.
   Subtraction	the voxel Raster Algebraic Operation is used to subtract two voxel Raster Dataset, that is, the value of the voxel in the corresponding position in the second voxel Dataset is subtracted from the value of the voxel in the first voxel Raster Dataset on a voxel by voxel basis. When using the subtraction operation, the order in which you enter the voxels Raster Dataset is important. If the order is different, the result is usually different.
   Multiplication	a voxel Raster Algebraic Operation is the process of multiplying the raster values in the Raster Dataset of two input voxels, voxel by voxel.
   Division	a voxel Raster Algebraic Operation is the process of dividing the raster values in the Raster Dataset of two input voxels, voxel by voxel.

   logical operation

   Logical operation, also known as Boolean Operation, makes a conditional judgment of "true" or "false" on the pixel value in the input Raster Dataset, and outputs it in the form of binary (1 and 0). The operation result is represented by 1 or 0, where 1 logically represents "true", that is, a voxel that meets the requirements of Algebraic Operation Expression, and 0 logically represents "false", that is, a voxel that does not meet the requirements of Algebraic Operation Expression.

   Common logic operations include And, Or, Not, and Xor. Each logic operation method is described in detail below.

   Logical operator Instructions for use
   • And: for logical "and", use & & in the expression dialog box Express. If and only if the voxel value of a voxel Raster Dataset satisfies two Algebraic Operation Expression simultaneously, the voxel value is true and is assigned a value of 1, otherwise, the voxel value is false and is assigned a value of 0.
   • Or: Represents the logical "or" and is represented by | in the expression dialog box. When the voxel value of the voxel Raster Dataset satisfies at least one of the two Algebraic Operation Expression, the voxel value is true and is assigned a value of 1; If the voxel value of the voxel Raster Dataset does not satisfy the two Algebraic Operation Expression, the voxel value is false, and the value is assigned as 0.
   • Not: represents the logical "not", which is represented by not () in the expression dialog box. When the voxel value of the voxel Raster Dataset does not satisfy the listed Algebraic Operation Expression, the voxel value is true and is assigned a value of 1; otherwise, the voxel value is false and is assigned a value of 0.
   • Xor: Represents the logical "exclusive or" and is represented by ^ in the expression dialog box. A voxel Raster Dataset is true and is assigned a value of 1 if and only if the voxel value satisfies only one of the two Algebraic Operation Expression; If the voxel value of the Raster Dataset satisfies (or does not satisfy) the two Algebraic Operation Expression at the same time, the voxel value is false and is assigned as 0.

6. Result Data

   • Datasource: All the Datasources under Current Workspace are listed. Select the Datasource to be saved by Result Dataset.
   • Dataset: Sets the name of the Result Dataset.
   • Pixel Format: Set the Pixel Format of the Result Dataset. The 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 .
7. Import/export parameters for Algebraic operations. The user can set the parameters of the "voxel Raster Algebraic Operation" "in the form of Config File through the" Import/Export "button at the bottom left.
   • Import: Click the "Import" button to directly import the Algebraic OperationConfig File saved in *.xml format to the "Voxel Raster Algebraic Operation" "dialog box for display.
   • Export: Click the Export button to save the Algebraic Operation Expression and other related Parameter Settings in the expression dialog box to a file in *.xml format for reuse.
After setting

the voxel Raster Algebraic Operation Parameters, the Raster Algebraic Operation operation can be performed.