Process operations (Grid category)

Creates a Terrain Ruggedness Index map (the average difference in elevation between a Grid cell and each of the surrounding cells) from a Grid.

Creates a Topographic Position Index map (the average difference between the elevation of a Grid cell and the mean of the elevations of each of the surrounding cells) from a Grid.

Creates an Aspect map (the azimuth, or angle, of the slope in a Grid cell) from a Grid.

Properties

Algorithm*

The aspect algorithm to use. Hom/Zevenbergen & Thorne.

Trigonometric*

Should the aspect values be returned as a trigonometric' angle (in degrees anti-clockwise from east/the X axis) instead of an azimuth (in degrees clockwise from north)? True/False.

Creates contour LineString Items from a Grid, at fixed intervals.

Properties

3D*

Should the LineString Items have their height set to match the contour level? True/False

Interval*

The interval between contour levels, as a simple value, or as an expression.

Offset*

The offset, relative to 0.0, to apply to the fixed interval contour levels, as a simple value, or as an expression.

Typical contour display:

Creates contour LineString Items from a Grid, at fixed levels.

Properties

3D*

Should the LineString Items have their height set to match the contour level? True/False

Levels*

The contour levels, as a space- or comma-separated list of values, or as a 'repeat string', e.g. '100 200 300' or '100 repeat 3'.

Typical contour display:

Creates a shaded relief map from a Grid. This process is suited to OS LandForm PANORAMA DTMs.

Properties

Algorithm*

The slope and aspect algorithm to use. Hom/Zevenbergen & Thorne.

Altitude*

The altitude of the light, in degrees between 90 (vertical) and 0 (horizontal), as a simple value, or as an expression.

Azimuth*

The azimuth of the light, in degrees clockwise from north, as a simple value, or as an expression.

Combined*

Should the shaded relief map be created using a combination of slope and oblique shading?

Exaggeration*

The exaggeration factor to apply to vertical values, as a simple value, or as an expression.

Z Ratio*

 The ratio between the vertical units and the horizontal units, as a simple value, or as an expression.

 Typical Hillshade display:

Explodes a Grid Item into one Point Item per Grid cell.

Property

Set Z

Should the 'Z' of the Point Items be set to the Grid cell value (in addition to an Item attribute)? True/False.

Creates a coverage of Polygon Items from a Grid.

Property

3D*

Should the LineString Items have their height set to match the height in the Grid? True/False.

Explodes a Grid Item into one Polygon Item per Grid cell.

Property

Set Z

Should the 'Z' of the Polygon Item vertices be set to the Grid cell value (in addition to an Item attribute)? True/False.

Creates a Roughness map (the largest difference in elevation between a Grid cell and those of the surrounding cells) from a Grid.

Creates a Slope map (the angle, or percentage, of the slope in a Grid cell) from a Grid.

Properties

Algorithm*

The slope algorithm to use. Hom/Zevenbergen & Thorne.

Percentage*

Should the slope values be returned as a percentage. Instead of an angle?

Z Ratio*

The ratio between the vertical units and the horizontal units, as a simple value, or as an expression.

Sets the value of all Grid cells that match a comparison against the 'from' value to the 'to' value.

Properties

'From' value

The original value to compare, as a single value, or as an expression, e.g. '123' or '_AverageGridVal# + 2 * _StdDevGridVal#'.

'To' value

The new value to use, as a simple value, or as an expression. e.g. '321' or '_NoDataGridVal#'.

Comparison

The comparison to use when testing the original value.

The full range of comparison options available are:

Less than
Less than or equal to
Equal to
Greater than or equal to
Greater than
Not equal to