Segment objects from measurements using expressions and models.

Parameters

Expression

Write the expression for the segmentation, examples can be found below. The following comparators can be used for the expression:

Standard arithmetic (+,-,/,* …) and comparison operators (=,>,< …) as well as some mathematical expressions (…) and constant values can be used in expressions.

Expand to see all available operator

Arithmetic Operator

Description

-

Subtract

+

Add

/

Divide

*

Multiply

%

Modulo

^

Raised to a power

Comparison Operator

Description

=

Equal to

|

OR

TRUE if any of the conditions separated by OR is TRUE

&

AND

TRUE if all the conditions separated by AND is TRUE

!=

<>

Not equal to

<

Less than

<=

Less than or equal to

>

Greater than

>=

Greater than or equal to

Function operator

Description

SQRT(N)

SIN(N)

COS(N)

EXP(N)

LOG(N)

LOG10(N)

AVG(N)

ROUND(N)

Constants

Description

TRUE

Always evaluates to TRUE

FALSE

Always evaluates to FALSE

INF

token value

PI

approximated to 3.14159

Model

Select model to apply to the expression.

Min area

The minimum number of pixels for an object to be included.

Max area

The maximum number of pixels for an object to be included.

If 0 no maximum area is defined.

Object filter

Use an expression to further exclude unwanted objects based on shape.

Properties that can be used for the Expression:

  • Area

  • Length

  • Width

  • Circumference

  • Regularity

  • Roundness

  • Angle

  • D1

  • D2

  • X

  • Y

  • MaxBorderDistance

  • BoundingBoxArea

For details on each available property see: Object properties Details

Shrink

Takes away numbers of pixels at the borders of the objects included in images.

Only visible when applicable

Link output objects from two or more segmentations to top segmentation. Descriptors can then be added to the common object output and will be calculated for objects from all segmentations.

Descriptors after object will be calculated for all three segmentations (Sample1, Sample2 and Sample3)

The segmentations must be at same level to be available for linking.

Examples

Using class

Segment object classified to sample class. Expression: class = sample

Using negative

Segment object not classified. Expression: class != none

Band index comparison

Indexing with 1 based index in band list. Expression (B10 > 1.5 or B15 < 2) and B20 <=1.2)

Band names can also be used instead of band numbers in the example the band names are HE and LE. HE > 20 and LE <40

HE and LE are only applicable to X-Ray detectors e.g., Detection Technology camera

Wavelength number

Using wavelength number. Expression: (W980 > 1.5 or W1024 < 2) & W1200 <= 1.2