Processes

The use of Processes and Process Operations have been substantially updated and are used extensively within the HTTP API to perform analysis and data manipulation.

Processes can be performed on single items, a group of items or an entire overlay.

They can be built into SIS Desktop for testing with user-defined Processes being stored in the Named Object Library.

Processes can be added as parameters (defined as JSON) after identifying the items which need to be included in the operation.

e.g. Process JSON for defining a buffer

{
"Operation": "Item.Buffer",
"PropertyMap": {
"_radius@": "1"
}
}

This needs to be added as a parameter:

Copy

GET http://CCL642.cadcorp.net:4444/geognosis/9/sessions/b2fe1626-7a87-44f9-87a1-f9496dc9a06f/Map/Overlays/2/items/I1/Geometry.geojson?process={"Operation":"Item.Buffer","PropertyMap":{"_radius@":500}}

Source Items

Be aware when running processes, the source is always left unchanged.

For example, if you run the following request to intersect two area features:

…/Map/Overlays/7/Items.json?process={"Operation":"Item.Intersect"}

the intersect operation will not delete the original features.

After running the process the overlay has two original items and an intersected area (item). Use the DELETE verb to remove original items if they are not required.

Accessing Libraries

Any processes you create in SIS and save are stored in a Named Object Library (NOL). These can then be accessed by the HTTP API.

A NOL can be added to the installation folder of GeognoSIS (usually C:\Program Files\Cadcorp GeognoSIS 9\Libraries). This is then automatically loaded into every session.

Alternatively you can load the NOL in a session using this request. This creates a usable NOL file into the session from its location at C:\temp\test.nol

For eg:

http://(user):4626/GeognoSIS/9.0/Sessions/43d3661d-2721-4ec7-a4d8-3d86df42f13f/Libraries.json?
path=c:\\temp\\test.nol

Result

{"Result":"Created",
"View":"Libraries/test.nol.json"}

You can check the Libraries available to you by using a GET request.

http://(user):4626/GeognoSIS/9.0/Sessions/43d3661d-2721-4ec7-a4d8-3d86df42f13f/Libraries.json

Result

{"Data":["Libraries/(temporary).json",
"Libraries/(standard).json",
"Libraries/test.nol.json"],
"Up":"../43d3661d-2721-4ec7-a4d8-3d86df42f13f.json",
"Representations":"Libraries",
"Operations":"Libraries.json?"}

TIP: Notice the new library is included in the list. From here you can explore the contents of the library further.

Moving through the Library structure you can find the ObjectTypes stored there, including Processes using Libraries/test.nol/ObjectTypes/Process/

Running the following GET request will return the JSON structure of the process:

http://ccd616:4626/GeognoSIS/8.0/Sessions/d5b3d66a-b3ac-4eaa-810f-761937c1f408/
Libraries/test1.nol/ObjectTypes/Process/tesing.bufferradiusitem.json

Response

{"Data":{"Operations":[{"Operation":"Item.Buffer","Properties":{"PropertyMap":{"_radius@":"BufferRadius&"}}}]},
"Up":"../Process.json","Representations":"tesing.bufferradiusitem","Operations":"tesing.bufferradiusitem.json?"}

The JSON for the process is defined here as: {"_radius@":"BufferRadius&"}

To use this in a subsequent request, you need to encode the variable type, in this case

&: {"_radius@":"BufferRadius%26%"}

JSON Representation of Processes

The process methods listed below are described using their JSON in the following pages.

General

Co py	Copies an existing Item
De compose	Breaks down Items with complex geometry into separate Items
Filt er	Filter Items using an expression
Group by	Group Items using an expression
So rt	Sort Items by a value

Construction

Create box	Creates a rectangular Polygon, around a centre point
Create ellip se	Creates an elliptical Polygon
Create li ne (bearing/distance)	Creates a LineString from a bearing and distance
Create p oint	Creates a Point Item
Create points in Polygon	Creates random points inside a Polygon
Create poin ts on LineString	Creates random points along a LineString
Create sec tor (bearing/angle)	Creates a sector Polygon from a bearing and angle
Create se ctor (start/end)	Creates a sector Polygon from a start and end angle
Join points	Joins the origin points of Items together into a LineString Item
Join points (advanced)	Joins the origin points of Items together into one or more LineString Items

Geometry

Bou ndary	Gets the boundary of an Item.
Clip in side	Clips parts of source Items that are inside a clipping Item from another Overlay
Clip ou tside	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 h ull	Creates a convex hull Polygon around an Item
Envel ope	Creates an envelope Polygon around the extents of an Item
Explode parts	Explodes each 'part', of an Item into a separate LineString
Explo de segments	Explodes each 'segment'
Explode verti ces	Explodes each vertex of an Item into a separate Point
Fa cet	Facets curved geometry segments into straight geometry
Fill	Fills the boundary of an Item
Join LineStri ngs	Joins LineString Items together to make a longer LineString Item, within a tolerance
M ove	Moves an Item in X and/or Y and/or Z
Remove i nterior loops	Removes interior loops (holes and islands) from Polygons, leaving only exterior loops
Reve rse geometry	Reverses the geometry of an Item
Rotat e	Rotates the geometry of an Item about a hook point
Scal e	Scales the geometry of an Item about a hook point
Smooth (mid-points)	Smoothes the geometry of an Item, keeping segment mid-points fixed
Smooth (vertices)	Smkkoothes the geometry of an Item, keeping vertices fixed
Strip geo metry	Strips the geometry of an Item, leaving an Empty Item

Clean/Simplify

Generalise(Dou glas-Peucker N)	Generalises geometry using a variation of the Douglas-Peucker algorithm that is limited by the number of output points
General ise (D ouglas-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 (Reuma nn-Witkam)	Generalises geometry using the Reumann-Witkam algorithm
Remove duplic ates (by expression)	Removes duplicate items based on an expression
Remo ve duplicates (by geometry)	Removes duplicate items based on their geometry
Remo ve self-intersections	Removes self-intersections, e.g. a bow-tie
Remo ve short segments	Removes segments shorter than a tolerance
Remo ve spikes	Removes vertices that cause a spike
Remove s traight segments	Removes vertices between straight, or near straight segments
Simpl ify	Simplifies the geometry of an item, so that it matches the OGC 'simple' form

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. Returns Brush, Pen and Symbol Items to "By Overlay"

Analysis

Buffer	Creates a buffer around an Item
Cluster	Clusters Items together within regular, rectangular grid cells
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
Intersect	Combines the Items using the intersect boolean operation
QZone buffer	Creates a QZone buffer around an Item
Subtract	Combines the Items using the subtract boolean operation
Symmetric difference	Combines the Items using the symmetric difference boolean operation
Union	Combines the Items using the union operation
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)

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

Create Terrain Ruggedne ss Index	Creates a Terrain Ruggedness Index map
Create T op ographic Position Index	Creates a Topographic Position Index map
Create aspect	Creates an Aspect map
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 h illshade	Creates a shaded relief map from a Grid
Create p oints	Explodes a Grid Item into one Point Item per Grid cell
Create p olygon coverage	Creates a coverage of Polygon Items from a Grid
Create poly gons	Explodes a Grid Item into one Polygon Item per Grid cell
Create roughness	Creates a Roughness map
Create slope	Creates a Slope map
Set cel l value	Sets the value of all Grid cells that match a comparison against the 'from' value to the 'to' value

Geocode

MapQuest Open	Connects to the MapQuest Open Geocoding service
Microsoft Bin g Maps	Connects to the Microsoft Bing Maps geocoding service
OS (GB) Code -Point Open	Searches OS (GB) Code-Point Open data, by postcode
OS (GB) Natio nal Grid Reference	Matches search strings against OS (GB) National Grid References
OS (GB) Nat ional Grid Reference (Jersey)	Matches search strings against OS (GB) National Grid References for Jersey

User-defined

Remove all attribut es	Removes all attributes from an Item
Strip styles	Strips all styling information from an Item