Bitmaps are optional, and a failure to supply bitmaps does not hinder GNE in any way. Bitmaps must be named "GNENodeXXX.bmp" where XXX should be replaced by a number between 1 to 240 (no leading zeros). The bitmaps will then be available for use when a node size interval of between 1 and 240 is selected by a node size expression, when the global shape has been set to "entity" on the Shapes dialog box, and the node size status has been set to "size:color". When the calculated interval for a node is 1, then the first bitmap is displayed; interval 2 causes the second bitmap to be displayed; etc. Because GNE allows 40 different intervals at once, there can be at most 40 bitmaps on any given network. Of course, different views may select a different set of 40 bitmaps. Intervals 241 to 255 are reserved for future use.
Use a graphics program to create bitmaps. Windows' Paint is an excellent choice. When creating bitmaps it is helpful if the bitmap has 16 or more colors. Theoretically, GNE can handle bitmaps of any size and color depth, but you should avoid gray-scale bitmaps or bitmaps greater than 200 pixels across. Click here for an image of a network with three bitmaps (cityscape-16, arrow-dot, I-94) showing the locations of centroids.
GNE treats the lower-left pixel of the bitmap as an indicator of the color to be drawn transparently. It is not possible to dynamically change the color of bitmaps. Bitmaps will not be provided as a standard part of GNE, but several sample bitmaps are on this page (below) for illustrative purposes.
Any or all of these bitmaps may be placed into the same directory as GNEwin.exe. These bitmaps will only show in GNE version 6.0.3 or higher.
The Width Status dialog box has the ability to display all the available bitmaps by number.
Bitmaps do not seem to slow GNE's various operations by any significant degree, but metafiles and plot files from networks can become quite big if there are many nodes with large bitmaps. GNE's labeling procedures were not modified to handle bitmaps, so node labels may not appear in convenient locations relative to the bitmap. Some experimentation with each bitmap may be necessary to achieve good label placement.
Bitmaps have several interesting uses beyond making the network look less boring. For example, it is possible to create a suite of several similar bitmaps of varying sizes. Then node size expressions can be used to select a bitmap of a specific size from this suite. The cityscape bitmaps (below) are an example of such a suite. Furthermore, it is possible to create a node type for simply displaying bitmaps at random locations on the network. Thus, it would be possible to decorate the network with road signs, signal heads, points of interest, logos, direction arrows, etc.
Because this is an experimental feature, we would like to hear back
from users about their experiences. Is there enough flexibility in
choosing bitmaps? Are there too few choices? Do you have any
interesting bitmaps you would want to share with other users through this
site? Should GNE be shipped with a suite of standard bitmaps?
The cityscape in 14 sizes:
GNENode11.bmp
GNENode12.bmp
GNENode13.bmp
GNENode14.bmp
GNENode15.bmp
GNENode16.bmp
GNENode17.bmp
GNENode18.bmp
GNENode19.bmp
GNENode20.bmp
GNENode21.bmp
GNENode22.bmp
GNENode23.bmp
GNENode24.bmp
Dot and red arrow series:
GNENode30.bmp
GNENode31.bmp
GNENode32.bmp
GNENode33.bmp
Treasure map X:
GNENode41.bmp
A 240 bitmap collection built from clip art:
GNENodes.zip
