# Model Expression

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:

Equals -

`=`

And -

`&`

Or -

`|`

Less than -

`<`

Less or equal -

`<=`

Larger -

`>`

Larger or equal -

`>=`

Different from -

`!=`

#### 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`

#### Shrink

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

### 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`

#### Wavelength number

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