Basic Map Navigation

Getting Started

When you open the Geocortex web-based map viewer in your Internet browser, you should see something that looks a lot like the image shown in Figure 1 below.

The map information is displayed in the Map Window ). Beside the Map Window is the Information Panel ), which displays information about the map and lets you interact with the map. The Information Panel displays the Layer List ), as well as Selections ) and interfaces for various tools and processes.

At the top of the viewer you can see the Toolbar ), where you will find tools to help you use your map. These tools allow you to navigate around the map, ask questions of the map, and otherwise interact with the information. Scale information ) and map coordinates ) are found at the bottom of the Map Window. The Map Window also includes an Overview Map ) that indicates the part of the map you are currently viewing.

If you are feeling lost, don't worry. Everything will be described in detail soon.

Figure 1. The Geocortex Essentials Web-based Map Application

Main components of the map viewer

Navigating Maps

Zoom Tools

Zoom Tools
The Zoom tools are unique to digital maps. They are very much like using an actual magnifying glass, as the icons imply. The main difference is you can't burn ants with them (yes, this is a cruelty-free technology). The magnifying glass with the little plus sign lets you zoom in (view the map from closer in), while the one with the little minus sign lets you zoom out (view the map from farther out). There are a couple of ways to use these tools.

First, click one of the magnifying tools to select it, then click somewhere on the map. With the Zoom In tool, the map zooms in. The center of the new map is wherever on the map you clicked the mouse button. The Zoom Out tool zooms out the same way.

Second, you can use the Zoom tools more precisely by pressing the mouse button somewhere on the map, holding it down, and dragging a box. When you let go of the mouse button, the new map extent will be the area defined by the box, whether you are zooming in or out.

Click here for a relevant, but not essential, discussion of scale.

Here are some other functions that make navigating maps easier:

Zoom to Full Extent

Zoom to Full Extent
The Zoom to Full Extent tool is a quick and easy way to zoom out as far as possible. Just click the tool and the map will zoom out to its maximum extent.

Jump to Extent
The Jump to Extent Box allows you to navigate directly to predefined extents, without having to pan or zoom. To jump to an extent, select the extent from the drop-down list and click the arrow (  ). If you delve into the Advanced section of this tutorial, you will learn how to add extents to the Jump to Extent drop-down list using the Extent Bookmarks tool.

Figure 2. Jump to Extent

Jump to Extent
Map Projection
The Map Projection Box allows you to dynamically change the map's projection. To change the projection, select a different projection from the drop-down list and click the arrow (  ).

Figure 3. Map Projection

Map Projection

Pan Tools
With a Geocortex map you can look at a specific area of interest by panning around the map. The Pan tool lets you slide around to different parts of the map. Suppose you want to go north (up the map). Take the Pan tool and grab (press and hold down the mouse button) onto the map, pulling it down. Whatever part of the map you grab with the little hand will end up where you let go of the mouse button. Just like in real life. This works for moving any direction on the map.

Tip:  You can also zoom in and out using the Scale Slider. Drag the slider towards the plus sign or minus sign to zoom in or out from the map, or click the plus or minus sign to zoom in or out by a fixed amount.

You can also pan using the Directional Pan tool located at the upper left of the Map Window. Click a direction arrow ( ) to make the map shift in that direction by a fixed amount. You can navigate in any direction by clicking and holding the mouse button, and then moving the mouse over different direction arrows.

Scale Box and Scale Bar

Another method of zooming uses the Scale Box (Figure 4). The Scale Box shows the current map scale. To change the scale, type the desired ratio and click the arrow (  ). This is a quick way to zoom directly to the scale you need.

Figure 4. Scale Box

The Map Window has a Scale Bar (Figure 5) for estimating distances. The Scale Bar also shows the current x,y coordinates.

Figure 5. Scale Bar

Note that the Scale Box and Scale Bar are for map navigation only, and may not be perfectly accurate. Without information about the size of your monitor or display device, it is impossible to accurately provide a ratio scale. An error will be most pronounced if you are operating a large monitor or a projection device running at a very low resolution, or if you are running a small monitor at a very high resolution. A 17" monitor running at a resolution of 800x600 or 1024x768 represents the scale more accurately.

Some maps have limits on the scales at which you can view the data, and some layers and map labels may only appear at certain scales. If the layer you need is unavailable ( Unavailable Layer ) at your current map scale, zoom in until the layer becomes available ( Available Layer ).

Wondering what those little icons mean? They are part of the Layer List. Just read on, and you will find out how the Layer List allows you to work with layers and interact with map information.

Next > Exploring the Information