Understanding Largest Empty Circles (LEC)

Have you ever needed to find the largest open space on a crowded map? Whether it's to determine the best location for a new facility or to analyze spatial patterns, the Largest Empty Circles (LEC) analysis is a powerful tool within GIS that helps us do just that.

What is LEC Analysis?

LEC analysis is a spatial algorithm used to identify the largest possible circle that can be drawn on a map without enclosing any features. This 'empty circle' gives us valuable insights into the distribution of features within a given area and helps in optimal spatial planning.

How Does LEC Analysis Work?

Imagine a park with trees planted at various points. Now, if we wanted to find the largest area of open space where no trees are present, we would use LEC analysis. The GIS software scans the map and calculates the maximum-sized circle that can fit between the trees. The center of this circle is the point that is farthest from any tree, and the radius extends out until it is just about to touch the nearest tree.

Applications of LEC Analysis

LEC analysis is useful in many fields, including urban planning, environmental management, and logistics:

• Urban Planning: Identifying the largest area without buildings for a new recreational space.
• Environmental Management: Finding a region in a wildlife habitat undisturbed by human structures.
• Logistics: Locating the optimal placement for warehouses within a busy distribution network.

Creating LEC(s)

Create your LEC(s)

1. At the top of the Layers Panel, click on the
   The Operations, Analysis, & Plugins window will open.
2. Under the "Analysis" heading > "Models" subheading, click on the link: "Visibility Probability (huff)".
3. Under the Heading 'Select Group', click the Select button.
4. Click to select the colour gradient or use "Create From Text (AI)" to generate your own.
5. Under the "Opacity" heading, you can type in a new value for the overall non-transparency of the heatmaps.
   You can also change the opacity value by clicking on the up/down buttons.

   This does not apply to Bubble/Circle One Color.

    

   • 0% is invisible.
   • 50% is see-through.
   • 100% is the solid colour.

    

6. (Optional) Check to Lock To Zoom and set the Zoom level.
7. Click the "CREATE LEC(S)" button.
8. A pop-up will appear, "LEC(s) Created". Click the "Ok" button.
9. In the top-right corner of the Operations and Analysis window, click on the "X" button.