Best Practices For Printing Maps With Opensource Gis Tools

Choosing the Right Map Projection

Selecting the appropriate map projection is a crucial first step when preparing to print a map. The projection determines how the curved surface of the Earth is represented on a flat plane, which can distort size, shape, distance, direction, and more. When printing, you’ll want a projection that accurately conveys the information needed while minimizing distortion in the printed region.

Common projections used for printing maps include:

Mercator: Conforms shapes but distorts sizes, best for navigation charts
Robinson: Balances shape, area, and direction distortions for a general world map
Albers Equal Area: Minimizes area distortions, useful for thematic maps showing data distributions
Lambert Conformal Conic: Conforms shapes well for mid-latitude regions like North America or Europe

Factors to evaluate when selecting a printed map projection include:

Table of Contents

The location and extent of the map area shown
Whether conformality, equal-area, or equidistant properties matter most
What distortions can be tolerated for the map’s purpose
Orientation preferences like a straight or tilted pole line

Testing different projections is key to finding one optimized for your specific data and print region. Many open source GIS programs allow previewing maps in various projections prior to printing.

Formatting Maps for Printing

Properly formatting maps is imperative for high-quality prints. Formatting steps involve configuring page layout, map frames, titles, legends, labels, and visual elements for an attractive print display.

For page orientation and dimensions, consider:

Landscape for wide geographic areas, portrait for tall regions
Standard paper sizes like 8.5″ x 11″ or 11″ x 17″
Matching paper size to the printer equipment available

Map frames should be sized to maximize use of the printable area while leaving suitable margins:

0.5″-1″ margins sufficient for most purposes
Consistency between left/right and top/bottom margins looks best
Titles can go above or below the frame area as space allows

Exporting maps at higher resolutions yields superior prints but larger files:

300 DPI sufficient for sharp 8.5”x11” prints
Higher DPI like 600+ better for large format plotters
Raster data looks best at resolutions matching its native resolution

Customizing Map Elements

Well-designed map elements effectively convey information while keeping maps uncluttered. Carefully customized symbology improves printed map clarity and aesthetics.

For labeling map features:

Prioritize labels for prominent resources like major cities
Use sensible point, line, and area label positions to avoid overlaps
Style leaders connect labels positioned away from features

Basic map elements to include are:

North arrow indicates orientation relative to true or magnetic north
Scale bar graphically shows distance conversions at printed size
Legends defining symbols, lines, colors used on the map
Neatlines delineating the mapped area if not a standard shape

Titles and text should be legible on the target paper size:

12+ point font for critical map lettering
Slightly smaller annotation text as space permits

Test prints at intended size to fine-tune element positioning and text formatting for readability.

Exporting Maps from GIS Software

Open source GIS programs provide flexible options for exporting print-ready maps.

In QGIS, map exporting choices include:

Layout > Export as Image: For PDF, PNG, JPG, TIFF, and other raster formats
Layout > Print: Direct printing to connected devices
Composer templates: Stores export configurations for reuse
Atlas tool: Batch exports numbered outputs for map series

GRASS GIS map exports via GUI or command line interface:

File > Export to Graphics: For PDF, PNG output with control of resolution, dimensions, more
d.out.file: Used in scripts to automate raster map exports

SAGA GIS provides program modules to export maps:

Save Grid as Georeferenced Image: Exports grid layers as GeoTIFF, GeoPDF, more
Create Standard Print Map: Automates colored, labeled print map output

Check intended use for exports and customize settings accordingly for optimal printed map designs.

Troubleshooting Common Printing Issues

When preparing GIS maps for printing, problems sometimes arise requiring troubleshooting steps like:

Oversize elements truncated at page edges
Blurry or pixelated maps with artifacts
Misaligned map frames or symbols at printed scale

To fix cropped or split maps:

Check layout for off-page objects and inset frames
Increase printable area dimensions if possible
Simplify elements to fit available printable space

For fuzzy printing or visible pixels:

Export and print at higher resolution DPI
Resize program windows to match print output dimensions
Rasterize vector layers if appearance too jagged

To resolve alignment issues:

Refresh view prior to exporting map image
Pan to realign improperly positioned elements
Preview print layout before exporting to double check

Test a variety of print configurations to determine optimal settings, and adjust as needed to obtain crisp, clean map outputs.