Process Operations
Process operations can be applied to items (for instance Item geometry or Item properties or raster data) and create new items from the results.
You can chain together different operations to create a unique Processes. This Process can be saved to and recalled from NOLs.
The complete list of processing operations are shown below.
Note: Properties marked with an * in the process descriptions are mandatory.
General
| Collect | Collects together the geometries of Items into a single Item, without applying any spatial operation. |
| Copy | Copies an existing Item |
| Decompose | Breaks down Items with complex geometry into separate Items, eg turns a MultiLineString Item into several LineString Items |
| Filter | Filters Item using an expression |
| Group by | Groups Items using an expression |
| Replace Text | Replaces all instances of a sequence of characters in a Text Item with another sequence of characters |
| Sort | Sorts Items by a value |
Construction
| Create box | Creates a rectangular Polygon, around a centre point |
| Create ellipse | Creates an elliptical Polygon |
| Create from WKB | Creates an Item from OGC Well-known Binary |
| Create from WKT | Creates an Item from OGC Well-known Text |
| Create line (bearing/distance) | Creates a line from a bearing and distance |
| Create point | Creates a Point Item |
| Create points in Polygon | Creates random points inside a Polygon |
| Create points on LineString | Creates random points along a LineString |
| Create sector (bearing/angle) | Creates a sector Polygon from a bearing and angle |
| Create sector (start/end) | Creates a sector Polygon from a start and end angle |
| Join points | Joins the origin points of Items together into a LineString |
| Join points (advanced) | Joins the origin points of Items together into one or more LineString Items |
Geometry
| 'Dig' shape | Gets the 'dig' shape (a concave hull) of an Item using Park/Ho's algorithm |
| Alpha shape | Gets the Alpha shape (a concave hull) of an Item, using Edelsbrunner's algorithm |
| Boundary | Gets the boundary of an Item |
| Chi shape | Gets the Chi shape (a concave hull) of an Item, using Duckham's algorithm |
| Clip inside | Clips parts of source Items that are inside a clipping Item from another Overlay |
| Clip outside | Clips parts of source Items that are outside a clipping Item from another Overlay |
| Close | Closes any open geometry, joining the end to the start |
| Convex hull | Creates a convex hull Polygon around an Item |
| Create medial axis | Creates the “medial” axis of a Polygon or MultiPolygon. |
| Create Roof | Creates a roof MultiPolygon from a Polygon or MultiPolygon, using the straight skeleton |
| Create Straight Skeleton | Creates the straight skeleton of a Polygon or MultiPolygon. |
| Create Wavefront | Creates ‘wavefron’ inner offsets of a Polygon boundary at set distances apart. |
| Ensure anti-clockwise | Reverses the geometry of polygonal Items with coordinates specified clockwise, making them anti-clockwise instead. Other Items are left alone |
| Envelope | Creates an envelope Polygon around the extents of an Item |
| Explode parts | Explodes each 'part', of an Item into a separate LineString |
| Explode segments | Explodes each 'segment', ie linear join between vertices, of each 'part', of an Item into a separate LineString |
| Explode vertices | Explodes each vertex of an Item into a separate Point |
| Facet | Facets curved geometry segments into a straight geometry |
| Fill | Fills the boundary of an Item |
| Join LineStrings | Joins LineString Items together to make a longer LineString, within a tolerance |
| Create Medial axis | Creates the 'medial axis' of a Polygon or MultiPolygon |
| Move | Moves an Item in x and/or y and/or z |
| Move Random | Moves an Item in x and y by a random distance, at a random angle |
| Move into nearest Polygon | 'Snaps' Polygon Items to nearest Polygon. |
| Move onto nearest line | 'Snaps' Polygon Items to nearest LineString Item. |
| Move to Point | ‘Snaps’ Items to the nearest Point Item |
| OOBB (aligned) | Creates an object orientated bounding box (OOBB) Polygon around an Item, aligned to the 'dominant' angle of the Item geometry |
| OOBB (minimum) | Creates the minimum (smallest area) object orientated bounding box (OOBB) Polygon around an Item |
| Remove interior loops | Removes interior loops (holes and islands) from Polygons, leaving only exterior loops |
| Reverse geometry | Reverses the geometry of an Item |
| Rotate | Rotates the geometry of an Item about a hook point |
| Scale | Scales the geometry of an Item about a hook point |
| Set Geometry | Sets the geometry of an item |
| Smooth (mid-points) | Smoothes the geometry of an Item, keeping segment mid-points fixed |
| Smooth (vertices) | Smoothes the geometry of an Item, keeping vertices fixed |
| Create Straight skeleton | Creates the 'straight skeleton' of a Polygon or Multipolygon |
| Strip geometry | Strips the geometry of an Item, leaving an Empty Item |
| Tessellate (circles, hexagonal-horizontal) | Tessellates a Polygon Item into a regular pattern of circles with centres aligned vertically |
| Tessellate (circles, hexagonal-vertical) | Tessellates a Polygon Item into a regular pattern of circles with centres aligned horizontally |
| Tessellate (circles, rectangular) | Tessellates a Polygon Item into a regular pattern of circles with centres aligned horizontally and vertically |
| Tessellate (circles, rhombic/diamond) | Tessellates a Polygon Item into a regular pattern of circles with centres aligned diagonally |
| Tessellate (hexagons, horizontal) | Tessellates a Polygon Item into a regular pattern of hexagons, with centres aligned horizontally |
| Tessellate (hexagons, vertical) | Tessellates a Polygon Item into a regular pattern of hexagons, with centres aligned vertically |
| Tessellate (rectangular) | Tessellates a Polygon Item into a regular pattern of rectangles |
| Tessellate (rhombic/diamond) | Tessellates a Polygon Item into a regular pattern of rhombic/diamonds |
| Create Wavefront | Creates 'wavefront' inner offsets of a Polygon boundary, at set distances apart |
Clean/Simplify
| Generalise (Douglas-Peucker N) |
Generalises geometry using a variation of the Douglas-Peucker algorithm that is limited by the number of output points |
| Generalise (Douglas-Peucker) |
Generalises geometry using the Douglas-Peucker algorithm |
| Generalise (Perpendicular Distance) |
Generalises geometry using the Perpendicular Distance algorithm |
| Generalise (Radial Distance) |
Generalises geometry using the Radial Distance algorithm |
| Generalise (Reumann-Witkam) |
Generalises geometry using the Reumann-Witkam algorithm |
| Remove duplicates (by expression) |
Removes duplicate items based on an expression |
| Remove duplicates (by geometry) |
Removes duplicate items based on their geometry |
| Remove self-intersections | Removes self-intersections, eg a bow-tie |
| Remove short segments | Removes segments shorter than a tolerance |
| Remove spikes | Removes vertices that cause a spike |
| Remove straight segments | Removes vertices between straight, or near straight, segments. |
| Simplify | Simplifies the geometry of an Item, so that it matches the OGC 'simple' form (eg by removing all self-intersections) |
Properties
| Remove all attributes | Removes all attributes from an Item |
| Remove attribute | Removes an attribute from an Item |
| Set property | Sets a property on an Item |
| Set styles | Sets styling information on an Item |
| Strip styles | Strips all styling information from an Item |
Analysis
| Buffer | Creates a buffer around an Item |
| Buffer (doughnut) | Creates a buffer around the boundary of a Polygon |
| Buffer (inside) | Creates a buffer around the boundary of a Polygon that only contains the parts that are inside the Polygon |
| Buffer (interior) | Creates a buffer inside a Polygon that excludes the parts of a doughnut buffer around the boundary of the Polygon |
| Buffer (outside) | Creates a buffer around the boundary of a Polygon that only contains the parts that are outside the Polygon |
| Buffer (variable) | Creates a variable sized buffer around a Line. Offers a different buffer size at the start and the end. |
| Create Thiessen Polygons | Creates Thiessen Polygons of influence around the hook point of Items |
| Dissolve | Merges Items based on attribute values. |
| Geodetic buffer | Creates a 'geodetic' buffer around an Item, ie a buffer that takes the curvature of the Earth into account |
| Getis-Ord (GI*) | Calculates the Getis-Ord Gi* statistic for each feature in a dataset. |
| Intersect | Combines the Items using the intersect boolean operation, ie only overlaps are kept |
| Overlay Append | Overlay Append |
| Overlay Clip | Overlay Clip |
| Overlay Erase | Overlay Erase |
| Overlay Identity | Overlay Identity |
| Overlay Intersect | Overlay Intersect |
| Overlay Symmetric Difference | Overlay Symmetric Difference |
| Overlay Union | Overlay Union |
| Overlay Update | Overlay Update |
| QZone buffer | Creates a QZone buffer around an Item |
| Subtract | Combines the Items using the subtract boolean operation, ie any overlaps between the first Item and the second and subsequent Items are removed |
| Symmetric difference | Combines the Items using the symmetric difference boolean operation, generating alternate geometries, ie any overlaps are removed |
| Union | Combines the Items using the union operation, ie all parts of both Items are kept |
| Viewshed (as Grids) | Creates 'Viewshed' Grids from the Item origin over source Grid Items from another Overlay |
| Viewshed (as QZone) | Creates a 'Viewshed' QZone from the Item origin over source Grid Items from another Overlay |
| Viewshed (as binary Grids) | Creates 'Viewshed' Grids from the Item origin over source Grid Items from another Overlay, containing only the cell values 1 (in Viewshed) and 0 (not in Viewshed) |
Cluster/Disperse
Cluster
| Cluster Items (by expression) | Clusters Items together based on attribute values |
| Cluster Items (within Polygon) | Clusters Items together that lie within the same Polygon from another Overlay |
| Cluster Items (by distance) | Clusters Items together based on distance between Items |
| Create cluster point (by distance) | Creates a cluster point from Items based on distance between Items |
| Create cluster point (by expression) | Creates a cluster point from Items based on attribute values |
| Create cluster point (by grid) | Creates a cluster point from Items within regular, rectangular grid cells |
| Create cluster point (within Polygon) | Creates a cluster point from Items that lie within the same Polygon from another Overlay |
Disperse
| Disperse (T) | Disperses Items into a 'T'-shape |
| Disperse (adaptive) | Disperses Items into the most appropriate shape pattern, eg a triangle for 3 Items, or a pentagon for 5 Items |
| Disperse (angled line) | Disperses Items into an angled line |
| Disperse (arc) | Disperses Items into an arc pattern |
| Disperse (archimedean spiral) | Disperses Items into an archimedean spiral pattern |
| Disperse (asterisk) | Disperses Items into an asterisk sign |
| Disperse (circle) | Disperses Items into a single circular ring |
| Disperse (circles) | Disperses Items into multiple concentric circular rings |
| Disperse (cross) | Disperses Items into a '+'-shaped cross |
| Disperse (decagon) | Disperses Items into a decagonol pattern |
| Disperse (diagonal cross) | Disperses Items into a diagonal, 'x'-shaped, cross |
| Disperse (diamond) | Disperses Items into a diamond pattern |
| Disperse (fan) | Disperses Items into a fan pattern |
| Disperse (hexagon) | Disperses Items into a hexagonal pattern |
| Disperse (horizontal line) | Disperses Items into a horizontal line |
| Disperse (logarithmic spiral) | Disperses Items into a logarithmic spiral pattern |
| Disperse (nonagon) | Disperses Items into a nonagonal pattern |
| Disperse (octagon) | Disperses Items into an octagonal pattern |
| Disperse (pentagon) | Disperses Items into a pentagonal pattern |
| Disperse (random) | Disperses Items randomly |
| Disperse (septagon) | Disperses Items into a septagonal pattern |
| Disperse (square) | Disperses Items into a square pattern |
| Disperse (squares) | Disperses Items into multiple squares |
| Disperse (triangle) | Disperses Items into a triangular pattern |
| Disperse (vertical line) | Disperses Items along a vertical line |
| Disperse along LineString (even spacing) | Disperses Items along a LineString, distributed proportionally, and spaced evenly, on each segment |
| Disperse along LineString (fixed spacing) | Disperses Items along a LineString, with a fixed spacing |
| Disperse around Polygon (even spacing) | Disperses Items around a Polygon, distributed proportionally and spaced evenly, on each segment |
| Disperse around Polygon (fixed spacing) | Disperses Items around a Polygon, with a fixed spacing |
| Disperse within Polygon (angled line) | Disperses Items in a regular grid in a fixed direction within a Polygon |
| Disperse within Polygon (boundary) | Disperses Items into multiple boundary within a Polygon |
| Disperse within Polygon (circles) | Disperses Items into multiple circles within a Polygon |
| Disperse within Polygon (horizontal) | Disperses Items in a regular grid from left to right within a Polygon |
| Disperse within Polygon (random) | Disperses Items randomly within a Polygon |
| Disperse within Polygon (squares) | Disperses Items into multiple squares within a Polygon |
| Disperse within Polygon (vertical) | Disperses Items in a regular grid from bottom to top within a Polygon |
Declutter
| Declutter Text (align) | 'Declutters' Text Items by changing their alignment |
| Declutter Text (offsett and rotate) | 'Declutters' Text Items by moving and rotating them |
| Declutter Text (offset) | 'Declutters' Text Items by moving them, and converting them to BoxLabel Items |
| Declutter Text (rotate) | 'Declutters' BoxLabel Items by rotating them |
| Declutter Text (shrink) | 'Declutters' Text Items by shrinking them, and converting them to BoxLabel Items |
Stack
| Stack Text (circular) | 'Stacks' Text Items into a circular pattern |
| Stack Text (fan) | 'Stacks' Text Items into a fan pattern |
| Stack Text (grid) | 'Stacks' Text Items into a grid pattern |
| Stack Text (radial) | 'Stacks' Text Items into a radial pattern |
Rubber-sheeting
| Create Displacement | Creates a Displacement Item, for use in rubber-sheeting |
| Create Rubber Sheet | Creates a Rubber Sheet Item, for use in rubber-sheeting, from the Displacement Items |
| Explode Rubber Sheet | Explodes a Rubber Sheet Item into Displacement Items |
| Rubber-sheet Bitmap (Fitted Linear) | Rubber-sheets Bitmap or Grid Items, based on Displacements on another Overlay using the 'Fitted Linear' transformation |
| Rubber-sheet Raster (Polynomial) | Rubber-sheets raster Items, based on Displacements on another Overlay, using a Polynomial transformation |
| Rubber-sheet Raster (Thin Plate Spline) | Rubber-sheets raster Items, based on Displacements on another Overlay, using the Thin Plate Spline transformation |
| Rubber-sheet Vector (Fitted Linear) | Rubber-sheets vector Items, based on Displacements on another Overlay, using the 'Fitted Linear' transformation |
| Rubber-sheet Vector (Inverse Square Weighted) | Rubber-sheets vector Items, using the 'Inverse Square Weighted' transformation |
| Rubber-sheet Vector (Linear Patch) | Rubber-sheets vector Items, based on Displacements on another Overlay, using the 'Linear Patch' transformation |
Raster
| Compress | Compresses a bitmap |
| Convert to grayscale | Converts a colour bitmap to a grayscale bitmap |
| Convert to sepia | Converts a colour bitmap to a sepia bitmap |
| Crop | Crops a bitmap |
Grid
| Aggregate Grids | |
| Create Terrain Ruggedness Index | Creates a Terrain Ruggedness Index map (the average difference in elevation between a Grid cell and each of the surrounding cells) from a Grid |
| Create Topographic Position Index | Creates a Topographic Position Index map (the difference between the elevation of a Grid cell and the mean of the elevations of each of the surrounding cells) from a Grid |
| Create aspect | Creates an Aspect map (the azimuth, or angle, of the slope in a Grid cell) from a Grid |
| Create contours (fixed intervals) | Creates contour LineString Items from a Grid, at fixed intervals |
| Create contours (fixed levels) | Creates contour LineString Items from a Grid, at fixed levels |
| Create hillshade | Creates a shaded relief map from a Grid |
| Create points | Explodes a Grid Item into one Point Item per Grid cell |
| Create polygon coverage | Creates a coverage of Polygon Items from a Grid |
| Create polygons | Explodes a Grid Item into one Polygon Item per Grid cell |
| Create roughness | Creates a Roughness map (the largest difference in elevation between a Grid cell and those of the surrounding cells) from a Grid |
| Create scatter grid (Barnes) | Creates a grid from point data using the Barnes interpolation method . More information here |
| Create scatter grid (closest point) | Creates a grid from point data using the value of the closest point to each feature |
| Create scatter grid (count) | Creates a grid from point data using the count of features within each grid |
| Create scatter grid (interpolate) | Creates a grid from point data using interpolation |
| Create scatter grid (sum) | Creates a grid from point data using the interpolation of the sum of values within a defined grid |
| Create scatter grid (inverse distance weighting) | Creates a grid from point data using Inverse Distance Weighting interpolation . More information here. |
| Create scatter grid (natural neighbour interpolation) | More information here. |
| Create scatter grid (sum) | Creates a grid from point data using the interpolation of the sum of values within a defined grid |
| Create slope | Creates a Slope map (the angle, or percentage, of the slope in a Grid cell) from a Grid |
| Divide Grids | |
| Getis-Ord GI* (Z score) | |
| Getis-Ord GI* (p-value) | |
| Grid * Number | Allows a grid value to be multiplied by a number or expression |
| Grid + Number | Allows a grid value to be multiplied by a number or expression |
| Grid - Number | Allows a grid value to be subtracted from by a number or expression |
| Grid / Number | Allows a grid value to be divided by a number or expression |
| Kernel density estimation | |
| Max(Grid, Number) | |
| Maximum Grids | |
| Min(Grid, Number) | |
| Minimum Grids | |
| Multiply Grids | Multiplies the value of two grids together. |
| Number - Grid | Subtracts the grid pixel value from a defined number |
| Number / Grid | Divides the grid pixel value by the defined number |
| Set cell value | Sets the value of all Grid cells that match a comparison against the 'from' value to the 'to' value |
| Set grid pixel type | |
| Subtract Grids | |
| Sum Grids | |
| Transform Grid |
Geocode
| Google Maps | Connects to the Google Maps geocoding service. A Google Maps ‘Application Key’ is required to use this geocoder . |
| Microsoft Bing Maps | Connects to the Microsoft Bing Maps geocoding service. A Microsoft Bing Maps 'Application Key' is required to use this geocoder. |
| OS (GB) Data Hub Names API | Connects to the OS Data Hub Names API geocoding service
Related Topics |
| OS (GB) Data Hub Places API | Connects to the OS Data Hub Places API geocoding service |
| OS (GB) Code-Point Open | Searches OS (GB) Code-Point Open data, by postcode |
| OS (GB) National Grid Reference | Matches search strings against OS (GB) National Grid References |
| OS (GB) National Grid Reference (Jersey) | Matches search strings against OS (GB) National Grid References for Jersey |
| what3words | Connects to the whatwords API, matching search strings against what3words addresses. A what3words ‘Application Key’ is required to use this geocoder |
User-defined
| Remove all attributes | Removes all attributes from an Item |
| Strip styles | Strips all styling information from an Item |