Grid

A Grid item is an item that is displayed as a raster image. This can depict a Digital Terrain Model (DTM) or the density of point data.

It is made up of coloured cells, or pixels, the colour corresponding to a numerical value.

This value could be the height above sea level of that cell (a DTM), or the number of burglaries in that area.

Properties

  • Bitmap file: _bmpfile$
    The file containing the Bitmap. Bitmap items which do not use linked files leave this property empty.

  • Bitmap type: _classDib$
    The type of image this Bitmap item displays.

  • Colour depth: _depth&
    The number of bits defining each pixel in a Bitmap. The more depth a Bitmap has, the more colours it can show simultaneously.

  • Colourset: _colourset$
    The Colourset object used by a Grid item. This affects how the Grid item is coloured. If you do not specify a colourset name then the Grid item's Pen colour will be used.

  • Compression: _compression#
    The compression which has been applied to the Bitmap data. Uncompressed Bitmap items have a compression of 1, and JPEG Bitmap items can have a compression as small as 0.1.

  • Grid value resolution: _GridValRes#
    The resolution of values in a Grid item. Each cell in a Grid item stores a 16 bit signed integer. The Grid item stores a single floating point multiplier which converts the integer cell values into grid values.

  • Height: _height&
    The number of rows in the Bitmap item.

  • Maximum grid value: _MaxGridVal#
    The highest value within a Grid item

  • Minimum grid value: _MinGridVal#
    The lowest value within a Grid item

  • No-data grid value: _NoDataGridVal#
    Shows the No-data value (for information only)

  • No-data value: _NoData&
    Change to set a specific data value to transparent. When a value is entered the Use no-data value is set to True.

  • Resample method: _resample&
    The method a Bitmap or Grid item uses when pixel values need to be resampled.

  • Resolution: _resolution#
    The resolution of a Polygon, QZone, or Bitmap item.
    For a Polygon item, the value is the resolution of the invisible cached QZone item. If there is no cached QZone item then the Polygon item's resolution is reported as zero.

    A QZone item is made up of progressively smaller squares. Its resolution is the size of the smallest QZone square.
    The resolution of a Bitmap item is the size of each pixel.

  • Transparent: _transparentColour$ /_alphaTransparency&
    Is the Bitmap item transparent? If a Bitmap is transparent then any light coloured pixels will not obscure the graphics which are underneath it. Some displays and printers do not fully support transparency.

  • Use no-data value: _bNoData&
    True uses the No-data value. False resets the No-data value to zero.

  • Width: _width&
    The number of pixels in each row of a Bitmap.

See also Item Properties