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Firefly Cartography with TatukGIS Software

Similar to the April 18 blog demonstrating how to create professional cartographic quality maps as TatukGIS projects, this blog presents how to design professional looking firefly maps (also called glowing maps or glow-maps) such as commonly used for scientific presentations, professional papers, and web pages. Glow-maps employ cartographic techniques that typically pair a dark desaturated basemap with a glowing technique to highlight features and areas of interest.

The following tutorial uses the desktop TatukGIS Editor to create glowing maps. Start by opening in the Editor two incidences (i.e., as two separate layers) of the world_8km.jpg raster image map file found in the sample data set. Then click on the topmost layer in the Legend to open its visual layer properties dialog and apply transparency and grayscale settings as presented in following images.

Two layers, each containing the same world map file, are visible in the Legend.
Transparency level for the topmost layer set to 65%.
​Grayscale setting for the topmost layer turned on.

The resulting desaturated raster image visible below will be our basemap.

​Desaturated image layer.

The area of interest (AOI) for this demonstration is the United States. Ensure the focus is on this area by darkening the surrounding areas. This is achieved by using an inverse polygon of the USA boundry polygon.

Open in the Editor the world.shp vector file from the sample data, select the polygon representing the boundaries of the United States, and use Layer/Export... menu item to save (export) the polygon feature to a new shapefile layer.

​Settings to export contents from the selected layer to a new layer.

Remember to mark the Selected objects checkbox to export only the selected polygon(s) from the layer.

​Setting to export only the selected object(s), in this case the
USA polygon boundary.

Add the just created usa.shp file to the map and turn off the world layer.

Now comes the tricky part. Start by zooming the map view to full extent and creating a new temporary layer.

​Usa.shp layer added as the topmost layer, world layer turned off, and a new
temporary layer in the process of being created.

Copy to the temporary layer the polygon definition provided below in the WKT data format.

POLYGON ((-175 -85,-175 -80,-175 -70,-175 -60,-175 -50,-175 -40,-175 -30,-175 -20,-175 -10,-175 0,-175 10,-175 20,-175 30,-175 40,-175 50,-175 60,-175 70,-175 80,-175 85,-175 85,-160 85,-140 85,-120 85,-100 85,-80 85,-60 85,-40 85,-20 85,0 85,20 85,40 85,60 85,80 85,100 85,120 85,140 85,160 85,175 85,175 80,175 70,175 60,175 50,175 40,175 30,175 20,175 10,175 0,175 -10,175 -20,175 -30,175 -40,175 -50,175 -60,175 -70,175 -80,175 -85,160 -85,140 -85,120 -85,100 -85,80 -85,60 -85,40 -85,20 -85,0 -85,-20 -85,-40 -85,-60 -85,-80 -85,-100 -85,-120 -85,-140 -85,-160 -85,-175 -85)

On the temporary layer, navigate to the Shape / Import shape from... menu item, paste this text (if required), and click the Import button.


​The polygon definition, in WKT format, to be imported into the new temporary layer.


The result is a big rectangle polygon covering almost the whole world.

On the legend, move the temporary layer to below the usa.shp layer and select in the usa.shp layer the shape (polygon) representing the USA boundary. Make a copy of that shape to the clipboard using Crtl+C or menu item Edit / Copy.

A new Clipboard layer is added to the project.

​New clipboard layer visible in the Legend.

Go to Tools / Tools Manager menu item. Select and run the Clipboard operations tool.

​Tools / Tools manager selection opens the Tool Manager dialog box.
​Run clipboard operations on the layer.

Select the layer_tmp layer on the legend, then select the big polygon contained in that layer. In the pop-up menu that appears, select Source - Clipboard as the operation type and click OK.

​Source-Clipboard selected as the operation type.

Now turn off layers usa and layer_tmp to see the the topological difference.

​Topological difference focuses attention on the AOI.

The resulting feature is on the temporary Clipboard layer. To be able to use this feature in the future, we need to save it to a new shapefile. Go to Layer / Export... menu item, save as usa_inverted.shp, and add this shapefile to the map. Then remove the Clipboard layer from the map by going to the Edit menu and clicking on Clear Clipboard.

Open the Vector layer properties dialog for the newly added usa_inverted layer and set area symbology as:

  • Area Color: black with Alpha = 102 (Hex: 66000000)
  • Outline Style: Clear

Render ​settings for area outside the AOI.

These settings produce a nice dark overlay outside the boundaries of the AOI, thereby focusing attention on the area of the United States.

​Dark overlay applied to area outside the AOI.

To further emphasize the AOI from the rest of the map area, let's try adding a gradient to the USA boundary.

Turn on the usa layer, move it in the Legend to be the topmost layer, and open the Vector layer properties dialog for this layer. In the General section of the dialog, enable Multipass rendering to take full advanange of multi-section symbolization.

​Multipass rendering technique enabled.

Using the plus sign (+) at the top of the dialog, create 5 sections for the layer, and assign Legend names for each section according to the following image and instructions. Legend names make the sections easier to find.

​Five sections established to custom render the usa layer.

Set the following symbology by section:

  • Section 1st:
    • Area-Pattern: Transparent
    • Outline-Color: 65FFFCES (light yellow wth 80% transparency)
    • Outline-Width: 0.1 pt
  • Section 2nd:
    • Area-Pattern: Transparent
    • Outline-Color: B5000000 (black with 75% transparency)
    • Outline-Width: 2 pt
  • Section 3rd:
    • Area-Pattern: Transparent
    • Outline-Color: 80000000 (black with 50% transparency)
    • Outline-Width: 4 pt
  • Section 4th:
    • Area-Pattern: Transparent
    • Outline-Color: 40000000 (black with 25% transparency)
    • Outline-Width: 6 pt
  • Section 5th:
    • Area-Pattern: Transparent
    • Outline-Color: 20000000 (black with 12.5% transparency)
    • Outline-Width: 8 pt

The above is an example of one of the ways to achieve a gradient effect.

​Gradients (inner and outer) added to the USA polygon boundary.

The resulting polygon outline has both inner and outer gradients. Suppose we want to use just the outer gradient. This is easily achieved by defining advanced symbology in the Line Symbology Editor. Set the following simple code for Outline-Style-Editor-Code for sections 2nd to 5th.

MOVE (0 5W)



​Line Symbology Editor code used to customize the line gradient.

This little trick enables us to change a double-sided gradient to single-sided.

​USA polygon boundary gradient is now singe-sided.

As anyone with common knowledge about creating maps knows, the default WGS 84 coordinate system is normally not the best choice for the map projection. Let's change the projection to one that is typical for the United States, like Albers Equal-Area Conic. This projection can be found in the dropdown list under menu File / Coordinate System / Projected System. The handy search tool can be used to quickly find any projection or coordinate system just by typing in the first few letters of its name or the EPSG ID (in this case, 102008).

​5,000+ coordinate systems with search function.

Now the map presentation looks much better!

​Map generated to the Albers Equal-Area Conic projection.

Now we advance to the most interesting part of this firefly cartography tutorial, the creation of glowing symbology for point features (representing cities).

Add to the project the cities.shp shapefile from the TatukGIS sample data folder.

Let's start by using an attribute query to filter only the cities located within the AOI. Set the Scope query in the Vector properties window to:

CNTRY_NAME='United States'

At the same time enable the Multipass rendering technique, which is necessary to obtain the glowing effect. Do not close the properties form.

​Renders only cities for which the country name attribute = 'United States'.
Multipass rendering enabled.

Create four sections for the cities layer and name the sections 1st through 4th (similar to as done with the usa layer).

​Four sections set up to custom render the cities layer.

The firefly effect can be generated based on any color. The best visual effect is obtained by using the so-called laser colors (like the colors of the Star Wars lightsabers). We will use here the Laser Red Color, found at: http://www.color-name.com/laser-red.color.

Firefly_26.jpg ​Attribution: lakuboffar, CC BY-SA 4.0
<https://cretivecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons.

Set symbology for markers as shown below.

  • Section 1st:
    • Marker-Style: Circle
    • Marker-Color: FFFFFFFF (white)
    • Marker-Size: 1.5 pt
    • Marker-Smart size: 0 pt
  • Section 2nd:
    • Marker-Style: Circle
    • Marker-Color: 40ED2F32 (laser red color with 25% transparency)
    • Marker-Size: 4 pt
  • Section 3rd:
    • Marker-Style: Circle
    • Marker-Color: 40ED2F32 (laser red color with 25% transparency)
    • Marker-Size: 8 pt
  • Section 4th
    • Marker-Style: Circle
    • Marker-Color: 40ED2F32 (laser red color with 25% transparency)
    • Marker-Size: 12 pt

That's all! A glowing map is ready for presentation.

You can play around with various parameters, e.g., color, transparency, width, and size, to create visual effects to meet any aesthetic requirement. Desired presentations can be exported to image files for use outside TatukGIS software.

​Firefly map featuring USA cities.

Using this tutorial and your specific data, it is possible to create fancy or uncommon maps like the following examples.

​Railway connections in Europe (data source:
https://eurogeographics.org, https://www.naturalearthdata.com).
World flight routes (data source: https://openflights.org/).

This blog was inspired by articles authored by cartographers John Nelson and Kenneth Field.


Posted: August 08, 2022
Filed under: EDT, STYLING