Global Mapper Frequently Asked Questions

Global Mapper is a really easy to use GIS, but it is pretty involved.  Here is a simple FAQ based on common things students have asked me over the years about GM.  This document is based on Global Mapper v20.1, updated with a few items from v21.1 (basically the same for our purposes).  The built-in GM help is very good, and I recommend you read it if you can't find your answer here, or email me. 
-Chris Connors

How do I get started with Global Mapper?
Open the program and click the globe icon to load some data.  To get into some of the basics probably the easiest thing is to watch this video.

How do I make a printable map in Global Mapper (either pdf or hardcopy)?
Choose the forth icon from the left, called the map layout editor, and looks like a tiny dialog box, or watch this video.

What is the basic layout of GM (or what are all of these things on the screen!)?     On the left is the Control Center it has the Layers.  On the top are Toolbars that contain Icons for most tasks.  If you hover over an Icon it gives you a hint as to what it does.  If you don't see a Toolbar visible, then go to the View Menu>Toolbars to make it visible. Taking up most of the screen is the Map View that shows your data.  You can zoom in or out and pan with the Icons on the Navigation Toolbar.  While the pointer will change depending on what you are doing, like editing, selecting, etc (see below), often times you can use the left button to click zoom, middle button to pan, and right click to zoom out.

What is a Workspace, and what am I saving when I Save the Workspace?     In general the Workspace is a pointer file to all your data, along with specific info on your project (like the projection).  It is the .gmw file that you save to your disk.  By a pointer I mean it references the location of other data on disk, or in the cloud, and does not store all of it in the .gmw file.  This is a good thing, particularly if you are loading lots of data over and over for different projects.  If you have created something in GM (like a line, see below) and not exported it yet (see below), and re-imported it (see below), then that data also resides in the .gmw file. 

GM feels slow sometimes, what can I do to make it faster?  GM is super fast particularly on our workstations, so if you think it is acting slowly, then you have probably loaded something from the cloud (see below) and it is trying to read that from the cloud every time you zoom.  Either that or you are dealing with a file that is enormous and you are loading/manipulating multiple gigabytes without knowing it.  The solution to either problem is to export a piece of the data (smaller area or resolution) to your local disk/sever (see below) and then load that back in instead. 

What is a Layer?    These are different data (Feature Types in GM-speak) that are on the Control Center (on the list on left side of GM usually).  Clicking the check box makes the Layer visible.

Why can't I see my Layer even though I have it checked?     GM displays Layers in order from top to bottom on the Control Center list on the left, but also displays by default raster data before vector data.  So generally to solve this problem you need to rearrange your Layers by clicking them and dragging them up or down.

What does it mean for a Layer or an item (line, pt, etc) to be Selected?     GM does a lot of operations (like editing, cropping) based on whether something is Selected (see below).

So how do I select something?     For an entire Layer right-click the layer and choose Select.  For an item, click the Digitizer Tool Icon at the top (it's looks like a pencil). Then left-click what you want to select.  GM uses the order of Layers to determine what is selected, with the layer lower on the Control Center taking precedence over the one above, just like displaying (see above).

How do I create a line?     First select it with the Digitizer Tool (see above), then click the Create Line Feature on the Digitizer (Create) Toolbar.  It looks like a pencil with a line.  Note, after you digitize the line a dialog box comes up with a lot of options.  The key one to keep in mind is what Layer you are putting it into.  So look at the options before just clicking OK.

How do I edit a line?     First select it with the Digitizer Tool (see above), then click the line.  It will highlight the line and one of the vertices. There are different editing icons on the Digitizer (Edit) Toolbar.  The Toolbar has a bunch of icons that have arrows coming out of points.  Hover over them to see what they do.

How do I add elevations to a line?     Have the line(s) selected (see above) and visible, and in the map right-click to get a pop-up menu and choose Attribute/Style Functions> Apply Elevations to Selected Features.

How do I export a Layer?     Have the Layer visible (see above) and right-click the layer to get a pop-up menu and choose Layer>Export.

How do I import a Layer, or add any data that I already have?     Drag the file from the desktop onto the map.  There are potentially a lot of options for import and so you want to read/try different ones until you get what you want.  You can always try clicking OK and the defaults may work, but they may not.

How will GM know where to put the data I import relative the rest of the data?     If your data is georeferenced then GM will on the fly reproject it into the current Projections/Datum.

What if the data is not georeferenced?     GM will prompt you to georeference it based on other existing data, or indications you have on the data like lon-lat marks on a scanned map.

How do I bring in (import) new data from the cloud?  Click the Connect to Data Online Icon (looks like a globe).

How do I change/define the Projection/Datum for a project?     If you are starting a new project then the first data you bring in (if it is georeferenced and has a Projection/Datum) will define the P/D.  If you want to change it then click the Configuration Icon (looks like a wrench).

How do I change other stuff like showing a Legend, Scale, Lon-Lat lines and other stuff?     Click the Configuration Icon (looks like a wrench).  When you want to do something to the whole project generally go there.

How do I see a 3D surface?     Click the Viewer Toolbar (usually on the upper right).  If you choose the 3D Box Icon it will bring up a separate 3D window. Use left mouse button to rotate, middle to pan, and middle to scroll, and right to zoom.

How do I see hillshade and change the illumination?     Hillshade by default is already on for a dem. To toggle it off or on click the Hillshade Icon (looks like a mountain) on the Viewer Toolbar (usually on the upper right).  To change the illumination azimuth, inclination, exaggeration click the Dynamic Hillshade Icon (looks like a mountain with a sun) to the left of the Hillshade Icon. You might also want to change the color of the shader by going to the Configuration Tool (icon looks like a wrench), click Shader Options, then Low Color Gradient Shader and change the color to a medium gray.

How do I make a polygon out of two lines?     Select both lines (see above), make sure they are very close together then combine them with Combine Line Features from the Digitizer (Edit) Toolbar.  Have one line with only one gap or opening, then Create Areas from Lines from the same Toolbar, but only select the one line.  See the how to make a polygon video if words don't cut it.

How do I make polygons that are water-tight adjacent to each other?     There are a couple ways to do it.  One is to use Cut Selected Areas from another Area in the Digitizer (Advanced) Toolbar.  That is useful for making islands (polygons surrounded by another polygon).  The second way is useful if you are starting with lines and going to make polygons from them (see above).  If that is the case then either have a copy of the line layer ahead of time and bring that in, or Split the Line in Digitizer (edit) Toolbar, then follow the steps above.  See water-tight video.

How do I make polygons different colors like on a geologic map?     To make polygons on a layer different colors, right-click the Layer, choose Options and then go to the Areas Style Tab.  Click Assign Random Colors to Features.  If you want to make all polygons of one formation the same color, then you have to have had edited the Attributes (right-click on the Layer).  After you have attributes defined then in the Area Styles at the bottom choose Style Same if Matches.  See different colors for polygons video.