Combo Overlay tutorial COP 2026 EN

Prerequisites

The following prerequisites should be met before starting this tutorial:

• This tutorial will take approximately 45 minutes.
• This tutorial relies on base knowledge about the editor interface and the creation of Overlays. If you have not yet followed the tutorials related to those subjects please do so first.
• This tutorial can be followed with any project of any arbitrary location, preferably with both roads and traintracks. 

Preparations

Take the following steps as preparation for following this tutorial:

• Start your project. This can be a pre-existing project, or a newly created project.

Introduction to the Combo Overlay

The Combo Overlay is a Grid Overlay which allows for the creation of custom spatial calculation models. It is comparable to raster calculators which can be found in other GIS packages such as QGIS. The principle on which it operates is that for each grid cell, other Grid Overlays may provide values, and the combo Overlay uniformly applies a (simple or complex) formula to compute a new resulting value for that grid cell, and does so for all grid cells.

Creating a simple masking calculation

To get started with a Combo Overlay, it is basically always necessary to have some other Grid Overlay in the same Project to run a calculation on.

Add a Traffic Noise Overlay.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar) → Environmental (Dropdown) → Traffic Noise

Adding the Traffic Noise Overlay from the ribbon.

This Traffic Noise Overlay will serve as the primary input to work with. It computes results based on built-in formulas for noise from traffic. Although it's possible to tweak the inputs and the legend of the resulting Overlay, the principles of the calculation and the results thereof are immutable.

The traffic noise overlay is a standard calculation model.

Add a Combo Overlay.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar) → Custom (Dropdown) → Combo

Adding the Combo Overlay from the ribbon.

The Combo Overlay will, by itself, not show any significantly relevant results. This is because no inputs have yet been set, nor has a relevant formula been entered.

The default results of the Combo Overlay are uniform before inputs and are irrelevant.

The Combo Overlay accepts a set of inputs, which are Grid Overlays.

Set Grid Overlay A to the added Traffic Noise Overlay.

Set the input A to the Traffic Noise Overlay.

Next, set the formula to:

A

This formula will directly output A.

Then, click on ""Update now" to recalculate the Overlays.

The result is that for each grid cell, the value of the input Overlay A, which is set to the Traffic Noise Overlay, is used directly as the result.

Notice that the legend of the Traffic Noise Overlay is directly applied as well. This is because the legend of the first input is automatically read out by the Combo Overlay as the default legend for the Combo Overlay itself.

The results of the Combo Overlay directly outputting the results of the Traffic Noise Overlay.

Just like with the Traffic Noise Overlay itself, it is possible to click on any location in the 3D Visualization and see the exact value calculated there.

The hover panel will display the name of the Combo Overlay, and the value of that location.

Using the Combo Overlay, it is possible to manipulate those calculated values. One often used principle is to "mask" data, which basically means to explicitly obscure or let through some values.

Modify the formula of the combo Overlay, so that it reads as follows:

IF(GT(A, 55), A, NO_DATA)

This formula will remove values lower than 55 from the results.

The formula now contains two logical operations, as well as a NO_DATA constant. The formula can be read as follows:

If ( IF ) it is true that A is greater than 55 ( GT ), in that case we use the value A. Otherwise, we return the value of NO_DATA, which is a constant meaning no value exists at that point.

Click on "Update now" to recalculate the Overlays.

The results of the Combo Overlay have now changed. Only in the places where the Traffic Noise Overlay computed a noise level of more than 55dB have results now been retained. In all other locations, the results have been discarded.

Only results in locations with significant noise, greater than 55.

Rasterizing and combining data

Combo Overlays are, in and of themselves, effective tools for manipulating data. Their effectiveness is determined by the inputs provided to them. Therefore, it is also important to know how to turn other data in the Tygron Platform into Grid Overlays as well.

To try this out, information about train tracks will be added to the Combo Overlay, or more specifically information about the proximity of train tracks.

Train tracks have a number of trains running on them. This can be visualized using an Average Overlay.

Add an Average Overlay.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar) → Distance (Left panel) → Avg & Interpolation

Adding an Average Overlay from the ribbon.

Set the "Input" to "Attribute: Specific Layer", and the layer to "BUILDINGS". This will ensure the Average Overlay is specifically geared towards consulting data from Buildings.

The Average Overlay will only consult the Buildings in the Project.

Next, set the "Attribute" to "NUM_TRAINS". The NUM_TRAINS attribute indicates how many trains move over nearby tracks per hour, as rasterized onto buildings.

The Average Overlay will refer to the NUM_TRAINS Attribute.

The "Cell averaging distance", which is set to 100m by default, can be left as-is.

Finally, click on "Update now" to have the Average Overlay recalculate.

The result will be an Overlay which highlights train tracks, with a radius of 100m. Or in terms more practical for this setup: for any given grid cell, the Average Overlay indicates whether a train track is within 100m.

The results of the Average Overlay when configured.

Any cell with a value of 0 only has cells in a 100m radius with 0's. If any cell within that radius would feature a train track, the computed (average) value would be slightly more than 0. This value serves as an effective filter to identify which cells are "near a train track".

Now, switch back to the Combo Overlay by selecting it in the left panel.

Re-select the Combo Overlay.

Add a second input for the calculation. For Grid Overlay B, select the added Average Overlay.

Add the Average Overlay to the list of inputs.

Modify the formula of the Combo Overlay, so that it reads as follows:

IF(GT(A, 55), ADD(A, IF(GT(B, 0), 5, 0)), NO_DATA)

This formula will increase the result, based on another input's value.

Instead of simply resulting in the value of A, the calculation will result in the combined values of A and either 5 or 0, depending on whether B has a value greater than 0. Since B will have a value slightly more than 0 when near a train track, this formula will now add an additional 5dB to the total result when near a train track.

Click on "Update now" to recalculate the Overlays.

The results are now subtly different, in that for all locations within 100m of the train tracks the noise level is computed as 5dB louder than otherwise.

The results when adding train noise to the masked results.

Tygron.AI for combo overlays: Improving operations

Prompt

Manual approach above questions

The above AI versions of the questions also have

Final assignments

• Add an additional Average Overlay, which only highlights the location of the train track and not the region around it.
• Add an additional Combo Overlay, which shows a color based on whether an area is away from the train tracks, near the train tracks, or itself train tracks.
  Tip: You can add the results of multiple GT() operations together in a Combo Overlay's formula.

Final notes

Although not part of the general explanation provided in this tutorial, the following notes are important to keep in mind:

• The editor interface will generally present the first 3 inputs (A, B, and C) of the Combo Overlay. However, a total of 10 inputs can be added and used, by switching to the "inputs" tab.

Tutorial completed

Congratulations. You have now completed this tutorial. In it, you have learned how to create Combo Overlays, and how to use Average Overlays to rasterize data for use in the Combo Overlay.