Simple Tool for Cropping Maps with Collars in Global Mapper

Have you ever tried to view multiple raster maps, such as topographic maps from the United States Geological Survey (USGS), only to have the collars overlap? Borders from raster maps that overlap cover the data in the adjacent maps, which looks messy and ruins the transition between them. Solving this problem can be a time-consuming and imprecise process requiring the manual cropping or removal of these borders. 

Global Mapper is a user-friendly application that offers various solutions to common data management challenges. In Global Mapper the automatic crop collar function efficiently and effectively solves this problem by recognizing the transitional boundary between the actual map and the supplementary information, such as the scale and legend. This boundary is called the neatline and is used by Global Mapper to determine which portion of the file to retain and which pixels should be removed from the display. This powerful tool can be used to quickly remove the white border around a digital raster graphic (DRG) file, the small black collar around a 3.75-minute digital orthophoto quadrangle (DOQQ), or the map collar around a BSB marine chart. Allowing the seamless viewing of adjacent maps. In this blog, we’ll walk through the stress-free steps on how to crop the border in these files.

1. Load the desired raster layers into Global Mapper – In this example, we have loaded four 7.5-minute series quadrangle GeoTIFFs from USGS covering an area of the Catskill Mountains in New York state. As seen in the screenshot, the overlapping borders obscure some of the map area in the abutting layers. These borders need to be removed.

1. GeoTIFF in Global Mapper with collar overlap
2. Select each of the rasters in the Control Center by right-clicking in the Control Center box and choosing Select All Onscreen Layers.
3. Right-click again and select Options… (Double-Click).
4.  In the resulting Raster Options dialogue box, select the Cropping tab.
5. Global Mapper dialogue box
6. Select Automatically Crop Collar (DRG/BSB/GeoPDF/etc.).
7. Click the OK button, and the maps will be automatically cropped to their neatlines resulting in a seamless view of all four maps.

GeoTIFF in Global Mapper after collar crop

If you’d like to try this workflow for yourself or would like to learn more about Global Mapper, download a 14-day free trial and request a demo today!  For more information, contact us.

If you enjoyed this blog, you may also find these other resources useful:

Cropping Map Collars in Global Mapper

Blue Got Mail – Removing the collar from a raster topographic map in Global Mapper