Cadcorp Index Dataset

SIS Desktop 9.1 uses an Index Dataset to manage lots of other dataset files which tile together to make a continuous map base. An Index Dataset can use multiple directories and/or multiple file formats.

Each Index Dataset is stored inside a SIS Workspace Definition (SWD) using a special "Index Overlay".

An Index Dataset uses Index Dataset Naming Conventions to tile together the map base.

An Index Dataset does not contain any data. It is a pointer to all files of a selected type(s) which reside in a selected folder or folders. It tiles together the dataset files into a grid to create a continuous map base from several existing files. For example loading in multiple OS (*.ntf) tiles to generate a map of the UK.

Compatibility:

• Cadcorp SIS Desktop
• Cadcorp SIS Desktop Express
• Cadcorp SIS ActiveX Modeller
• Cadcorp SIS ActiveX Manager
• Cadcorp SIS ActiveX Viewer
• Cadcorp GeognoSIS

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Dataset Properties

• Attributes: _attributes$
  A list of attributes held by the dataset.
  
  
• Cache tile paths: _bCacheTilePaths&
  Cache the tile locations instead of performing a (potentially expensive) re-scan of the folder(s) when opened as part of an SWD. True/False.
  
  
• Class name: _class$
  The class name of the dataset.
  
  
• Coordinate Reference System: _projection$
  The dataset Coordinate Reference System in Open Geospatial Consortium (OGC) Well-Known-Text format. (Notice that some SIS Desktop 9.1 Coordinate Reference System objects are not supported in OGC.)
  
  
• Description: _DESC$
  A textual description of the object.
  
  
• EPSG Code: _epsg&
  The matching EPSG code, if any.
  
  
• Editable: _bEditable&
  Is the dataset editable? True/False
  
  
• Feature table: _featureTable$
  The Feature Table which dataset items with no Feature Table of their own use when their Feature code is set. This Feature Table is also used to get information about available feature codes, and to create a default Feature Filter.
  
  Note: This does not override the Feature Table on an item.
  
  
• Gateways: _bGateway&
  Does an Index Dataset display tile outlines (using Gateway items) for all of the tiles found? True/False.
  
  
• Label: _bLabel&
  Does an Index Dataset display BoxText labels for all of the tiles found? True/False.
  
  
• Layers: _layers$
  The set of all values the Layer property for all items in the dataset.
  
  
• Maximum number of open Gateways: _nMaxGatewayOpen&
  The maximum number of Gateway sub-datasets a dataset should attempt to open simultaneously.
  
  
• Maximum number of open tiles: _MaxOpen&
  The maximum number of tiles that an Index Datasetwill attempt to open at once, in the range 0 to 1024.
  
  Setting the maximum to 0 will make the Index Dataset display tile outlines (using Gateway items and BoxText labels for each tile found, but not any data in the tiles themselves, thus automatically creating a Key Map.
  
  
• Modified: _bModified&
  Has the dataset been modified? True/False.
  
  
• Name: _name$
  The dataset name. For a file-based dataset this will be the filename.
  
  
• Next item id: _idNextItem&
  The Item ID which will be used for the next Item created in this dataset.
  
  
• Notes: _notes$
  User notes on dataset.
  
  
• Number of Items: _nItems&
  The number of items in the dataset.
  
  
• Overflow for tile items: _fractionOverflow#
  The fractional overflow of an Index Dataset, in the range 0.0 to 1.0.
  
  An Index Dataset uses this value when the map view changes and they attempt to open any tiles which fall within the new view. A value of 0.0 will do no padding, and a value of 1.0 will force two extra rows and columns of tiles to be opened (if the tiles exist). Values between 0.0 and 1.0 may open extra rows or columns of tiles depending on the value and how close to the tile edges the new view extents are.
  
  This value is useful for viewing an Index Dataset which contains tiles whose data overflows the tile edges.
  
  
• Pyramid: _bPyramid&
  Should an Index Dataset attempt to open dataset tiles with different sizes? True/False.
  
  
• Recursive: _bRecursive&
  A boolean value controlling whether a recursive search through child folders should be done when searching for the datasets data. True/False.
  
  
• Scale: _scale#
  The dataset scale.
  
  
• Size: _size@
  The amount of memory, in bytes, that the dataset uses.
  
  
• Size for tile labels: _fractionLabel#
  The fraction of the height of an Index Dataset tile used to calculate the tile label text height, in the range 0.001 to 2.0.
  
  The tile label text height is calculated as follows:
  
  TextHeight=(TileHeight)*(_fractionLabel#)/(NumberCharactersInLabel)

  
• Tile paths: _tilePath$
  A semi-colon-separated list of directories and file extensions used by an Index Dataset, e.g. "C:\Local\*.bds;C:\Local\*.bmp;D:\Network\*.bds".
  
  
• Tile paths (after recursion): _tilePathEx$
  A list of directories and file extensions used by an index dataset, separated by semi-colons, e.g. C:Local*.bds;C:Local*.bmp;D:Network*.bds
     
• report: _report$
  This reports: _name$, _DESC$, _crs$, _epsg&, _loadTime#.
  

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