A graticule is a network of lines representing the Earth's parallels of latitude and meridians of longitude. While a graticule represents lines or latitude and longitude, a map-grid represents lines in other units, such as meters or feet. A graticule or map-grid can be added to a map by selecting the map and clicking the Map | Add | Graticule command. Graticules and map-grids are a great way to add more context to your maps. Display your axes in the units of your data (feet, meters, etc.), and add a graticule to show latitude and longitude values too! Do your clients need a map displayed in multiple units? Project your map in UTM meters, but display a grid in feet!
To demonstrate this feature, I've created a map of Colombia that is projected in the MAGNA-SIRGAS coordinate system, which uses meters for its unit. I've added a graticule as a map-grid to represent grid line intersections in meters, and I've added a second graticule to show lines of latitude and longitude. The image below shows the map before adding the graticules.
Map of Colombia, before adding graticules.
To add each graticule, I selected the Map object in the Object Manager and clicked the Map | Add | Graticule command. Next, I selected each Graticule (one at a time) and made changes in the Property Manager. Let's take a look at some of the properties available for graticules!
The Layer and Info pages of the Property Manager look similar to those pages for other objects. On these pages, you can change the layer's opacity and edit attributes. The General page of the Property Manager has options to specify the units the graticule uses. The options in the Units list are dependent upon the map's target coordinate system. If the map is projected, the available units include Degrees (Lat/Long), Millimeters, Centimeters, Meters, Kilometers, Inches, Feet, Survey Feet, Yards, and Miles. If the map uses a known unit, the linear units in the preceding list are available, if the map has a datum, Degrees (Lat/Long) and Unknown map units are available, and if the map is unreferenced, only Unknown map units is available. For the Style, specify whether lines are displayed all the way across the map or crosses are displayed where the lines intersect. Set the properties of the lines or crosses in the Line properties section. The last two sections on the General page allow you to set the spacing of the graticule lines in the X and Y directions. Graticule lines are drawn starting at the specified Origin and are equally spaced on either side, according to the specified Spacing value. An example of the General page of the Property Manager for Graticule objects is below.
Sample General page of the Property Manager for a graticule.
The Labels page of the Property Manager displays the options and label formats for graticule labels. You can set properties such as Location, Orientation, Placement, Frequency, Offset, Show ticks, and Tick length separately for the Longitude Labels and Latitude Labels. The properties in the General section apply to all labels/tick marks on the graticule.
Labels may be positioned at both ends of the graticule lines, on either end of the graticule lines, or the labels may be omitted from the map. Label Orientation specifies whether the labels are displayed horizontally, vertically, along/parallel to the line, or perpendicular to the line (Normal to line). Use the Placement option to have the labels placed inside or outside the mapframe. The Frequency property tells Surfer whether to place labels at every line, every other line, every third line, and so on, depending on the value that is entered. The origin line (specified on the General page of the Property Manager) is always labeled, and the Frequency value begins counting at the origin line. The Offset property controls the label distance from the tick or mapframe. When the Placement is set to Outside, increasing the Offset moves the labels away from the map, and when the Placement is set to Inside, increasing the Offset moves the labels into the map. Toggle Show ticks to turn the display of the ticks off and on, and enter a new value to adjust the Tick length.
Sample Labels page of the Property Manager for graticules.
The properties in the General section are not new to Surfer and may be familiar if you've set properties for other labels and lines previously. However, I did want to point out a new label Type: DMS (Lat/long)! You now have control over the display of latitude and longitude values. Display the labels in decimal degrees or in Degrees, Minutes, Seconds format! Next to Label Format, an example of the specified DMS format is displayed. Check the Use symbols box to display symbols for degrees(°), minutes('), and seconds("), and check the Embed space box to add a space between the symbols and before the hemisphere suffix. Additionally, you can toggle the Suppress leading zeros and Suppress trailing zeros boxes to further customize your display!
Below is the map of Colombia after adding the graticules. The grey crosses represent a graticule as a map-grid in meters, and the blue lines show lines of latitude and longitude, labeled in Degrees, Minutes, Seconds format.
Finished map, with graticules.
To read more about graticules, see the Surfer 13 help. To access the help, click the Help | Contents command. In the help, click the Contents tab and then navigate to Surfer 13 | Map Objects | Graticule | Graticule.
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