GRASS Tutorial for GEOG2210 – Tutorial 26 – Saving the Map as a Graphic File

You want to save your map as a graphics file so you can export it into some presentation software (e.g. PowerPoint) or edit it using a graphics program (e.g Inkscape). , it is important to remember that the image in the Map Display window is not a single image file. GRASS is simply displaying the map layers and other map elements in the Map Display window using the various settings that you have specified. You can recreate the map display (excluding the map elements) by saving your settings in a workspace (see Powerpoint, MS Word or a graphics program, you will need to save the image as a graphics file. This tutorial explains how to save a map as a graphics file. .png, .jpeg, or .tif file, and then use a graphics application, commercial examples would be Adobe Illustrator or Adobe Photoshop, to add the 'finishing touches' to the map. Because of its limited cartographic capabilities, this is pretty much the only technique for producing publication quality maps using GRASS. Instruction on how to use sophisticated graphics programs like Illustrator or Photoshop goes beyond the scope of this series of tutorials. The maps you produce for GEOG2210 should not require the extensive use of any graphics program. However, developing some basic skills in the use of graphics programs would certainly be time well spent. Highly recommended are two freeware programs that run on both Windows and and Mac OSX systems . The following demonstrates saving a small scale map of mainland Scandinavia (Norway, Sweden, Finland and Denmark) as a portable network graphics (.png) file. The .png file can then be imported or pasted into another application. The map itself is based on data in the The Map Display window has been resized to create white space (margins) at the top and bottom of the map. The Add Map Elements tools (see ) has been used to add text to to the map (a title and information about the map projection) and a scale bar. The text and scale bar have been positioned in the the map margins. The current image size in pixels will be displayed. In the example the width is 589 pixels and the height is 897 pixels. The image size in pixels is a function of the dimensions and resolution of the computer monitor. This example was created on a computer with a 120 pixel per inch (PPI) monitor and is 4.91 inches wide by 7.48 inches high on the monitor. Creating the map on a larger monitor (so the image could be wider and taller) or a higher resolution monitor (Apple's Retina display has a resolution of approximately 220 PPI) would result in a greater width and height in terms of pixels. A good discussion of pixels and monitor resolution, as well as some useful tools for calculating image size and resolution, can be found at If you are planning on using the image at it's current size and resolution you can simply click the OK button and save the file in the desired graphics file format. If you are planning on enlarging the image, or printing it at a higher resolution, you can increase the pixel width and height of the image. This will result in a larger sized image file, but improve the quality of the final project. The Template option allows you to force the image to have dimensions that match typical computer displays. White space will be added to the image so that its aspect ratio (width to height ratio) matches that of the computer display. The settings you select will depend on your 'plan' for the image. The following are examples of two typical export operations. For this example the plan is import the image file into InkScape, use Inkscape to add name labels to the countries and then print the final map on an inkjet printer at a resolution of 300 DPI. To ensure a high quality for the printed image we will increase the pixel width and height of the image by a factor of 3, so the exported image will have a pixel width of 1767 pixels ( 3 x 589 pixels) and a pixel height of 2691 (3 x 897 pixels). A dialog box will open prompting you for a save location, name and type for the exported graphics file. In the above example the image file is being saved as a .png file in a folder called The following screenshot shows the new file opened in Inkscape. Labels have have been added to the countries using the Inkscape text tools. The plan is to use the map in a PowerPoint presentation on Scandinavia. As the map will only be displayed on a computer screen or projected from a computer screen there is no really need to increase the pixel width and height of the image. We will use the current setting. The dialog box opens prompting you for a save location, name and type for the exported graphics file. In the above example the image file is being saved as a .png file in the folder called Source.


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Last Modified: April 24, 2016 @ 8:08 am