Export Map to CGM Plot File
Use the CGM Plot Options dialog (CGMOPTIONS GX) to set the options for exporting a map to CGM (Computer Graphics Metafile). The dialog is opened from the Advanced Options of the Export Map dialog when the CGM Plot (*.cgm) is selected as the output format.
CGM Plot Options dialog options
Application Notes
OPTIONS PARAMETERS:
Width and Height
The width switch is used in conjunction with the height switch to define the paper size in the plotter. When both width and height are specified as positive numbers, the output is scaled to fit on the paper and is nearly centered on the paper. When width and height are specified as positive numbers, the plot will automatically be rotated if the rotated plot would have a larger area than the un-rotated plot. The rotated plot is often called landscape mode by other plotting software. If you specify either the width or the height parameters, you should specify both. The width and height must be specified in plotter units.
If the width and height are less than or equal to zero, then the program assumes that the paper size is "unlimited". (This assumes that the plot will be paneled by the plotter if needed). If the width and height are less than zero, the absolute value of width and height are used as x and y offsets for the plot. By default, the width and height parameters are set to 1, meaning that an unlimited plotting area is available, and the plot is shifted 1 plotter unit in both x and y.
Units
This switch specifies the plotter units per inch. For instance, if you are writing to a plotter that needs x and y in centimeters, you would set units 2.54 to specify that the plotter units are in centimeters. By default, inches are assumed to be the plotter units.
Default Font
The Geosoft plt file uses a naming convention for fonts. One of the names is "default", but the plt file has no entry specifying which font is actually the default. Use this switch to set the default font to one of the following Geosoft fonts:
sr - Simplex Roman, ss - Simplex Script, cr - Complex Roman, ci - Complex Italic, cs - Complex Script, tr - Triplex Roman, dr - Duplex Roman,
fast - A small ugly font that is faster to draw.
If no DefaultFont switch is specified, then the Simplex Roman (sr) font is used as the default.
Colour Flag
This switch is used to specify if the plotter supports indexed colour, direct colour, grayscale or only black and white plotting. If the plotter is black and white, but if the software driving the plotter approximates grey by dithering, you should use grayscale as the ColorFlag. The default value for this switch is colour (i.e. indexed colour). If you are using anything other than direct colour, you may also need to specify the number of available colours or grey levels with the Ncolors switch.
Be careful when using direct colour. If the cgm interpreter and/or the device it is driving support direct colour well, then you will almost certainly get better rendering of images, especially shaded relief map images. However some cgm interpreters do not handle direct colour well. We suggest you experiment with indexed and direct colour files to see which works best with your cgm interpreter.
If you do not have shaded relief images on your map, you probably don't need direct colour. One price of direct colour plotting is that the output cgm file (if there is a large image to plot) will be nearly 3 times larger than the indexed colour cgm file.
Ncolors
Specify the number of colours or grey levels available on the plotter with this switch. The num ber of colours should be between 2 and 256. If it is outside of this range, the closest endpoint of the range is used. If the number is set below the total number of distinct colours requested in the plt file, then a colour compression algorithm is used to try and approximate the desired colours as well as possible. If the number of colours available in the plotter is much less than desired, you may see a lot of colour difference in the plot as opposed to the screen image of the same data. If the ColorFlag is set to mono, the number of colours is automatically set to 2.
If no Ncolors parameter is set, the default is 256 colours for indexed colour plotting or 256 grey levels for grey scale plotting. When direct colour plotting is desired, the Ncolors option is ignored.
Fade
The fade switch can be used to adjust the brightness of the colours in the plotter output. If your plot has a lot of solid colour fill areas, and also has a lot of text or symbol information superim posed on top of the fills, you may want to make the fill colours less bright so the superimposed information can be read more easily. The fade is expressed as a percentage. The perceived colour fading vs. specified percentage is subjective, but higher positive values will produce more washed out colours and more negative values will produce darker colours. If the fade value is less than 75 or greater than 75, the closest endpoint of the range is used. Setting fade to 50 will wash out the colours quite a lot, by our subjective evaluation. The default is a fade of zero percent (no fading of colours). The fade only affects non primary colours in the colormap. Primary colours are red, green, blue, cyan, magenta, yellow and black. These primary colours will not be faded. The fade parameter is ignored if direct colour plotting is specified.
Ink Filter
If you use the same red, green and blue values for a colour and display the colour on a screen and on a piece of paper, the colour may look a fair bit different on each device. An empirically deter mined filter is available to shift the plotter output colours so that they look more like the screen colours. This filter is based on a colour map with a lot of reddish, bluish, yellowish and greenish colours. The filter works reasonably well with this colour map. If you need a considerably dif ferent colour map, the filter may not work as well for you. By default, the InkFilter is off. The InkFilter parameter is ignored if direct colour plotting is specified.
Image dpi
This parameter specifies how many image cells per plot unit to use. Images in the Geosoft files are interpolated to this resolution. The default value is determined from the cell spacing of each image to be drawn. If the value specified for this parameter or calculated from the geom etry of each image is greater than the plotter resolution then the plotter resolution is used. This parameter can be lowered (e.g. set Imagedpi 50) to speed up image plotting at the price of lower image. If you make Imagedpi higher, the plotting will take a little longer but the images may possibly show more detail.
Plot dpi
This parameter specifies the resolution of the plotter in dots per plot unit. The default value is 400 dots per plot unit. This is used to determine if Imagedpi is reasonable and to make certain that huge images are pieced together seemlessly.
Image Position
This switch specifies whether images will be drawn in the foreground (on top of the lines, text, etc.) or in the background (below the lines, text, etc.). If the images and vector graphics occupy the same part of the map, one will be obscured by the other. If you want the image partially obscured by the vector graphics, use background for the image position. If you want the vector graphics obscured by the images, use foreground for the position. The default is to draw the images in the background.
Broken Image
Some cgm previewers do not seem to support drawing of images as cell arrays. With the HiJaak Pro version 4.0 previewer running on Windows NT 4.0 is that it ignores cell arrays in cgm files. If your previewer does not support cell arrays, you can set this switch to yes or on to force images to be output as a series of lines. The CGM files produced when this switch is turned on may be up to 20 times larger than if the switch is turned off. However, this may be the only way to see image data if your cgm previewer is broken. By default, the BrokenImage switch is set to no and images are written to the cgm file as cell arrays.
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