Travel Distance Overlay Tutorial

Prerequisites

The following prerequisites should be met before starting this tutorial:

• This tutorial relies on base knowledge about the editor interface. It is also recommended to have completed the tutorial(s) related to the Combo Overlay. If you have not yet followed the tutorials related to those subjects please do so first.
• This tutorial can be followed with any Project based on real data with houses and a network of roads

Introduction to the Travel Distance Overlay

The Travel Distance Overlay is a spatial calculation for determining whether it is possible to reach a given destination (or one of multiple destinations), from any given location, via a pre-defined network of allowed routes. In contrast to simpler Distance Overlay calculations, which performs calculations "as-the-crow-flies", the Travel Distance Overlay specifically takes into account whether it is actually possible where movement is possible. This creates a more practical result in terms of reachability.

The calculation works by establishing a collection of relevant "destinations", and determining a valid grid of "traversable" locations. Then, starting at the destination and only taking into consideration traversable grid cells, each adjacent cell is marked as reachable. Cells adjacent to those are also marked as reachable, and this process is iteratively repeated until the distance covered by such as a sequence of adjacencies has reached the maximum amount of distance to compute. In other words, starting at each "destination", valid routes propagate across the network of allowed traversable routes until the maximum distance has been reached.

The Travel Distance Overlay can be used to calculate which locations can be reached when starting at a specific point of interest. It can equally be used to calculate from which location it is possible to reach a point of interest. Mathematically, these calculations are identical, just reversed in conceptual direction.

For completeness' sake it is prudent to state: the Travel Distance Overlay uses the term "Destination" for the locations to calculate from- and to-, and in terms of implementation the calculation starts out at these destinations.

Creating a simple Travel Distance calculation

A Travel Distance Overlay requires two spatial inputs: destinations and traversables.

Projects created with real world data virtually always include some form of road network, which a Travel Distance Overlay will use by default as its traversable input. Destinations must always be explicitly provided, either by manually drawing in relevant locations, importing them from an external source or file, or by calculating them on-the-fly.

Next, the most important setting for a Travel Distance Overlay is the maximum allowed travel distance, which is a simple numerical setting.

Setting up a destination

Begin by setting up a dataset of one or more destinations of interest. Find a place in the Project map which it would be relevant to travel to, such as a park or other outdoor recreational location.

Add a new Area to the Project.

Editor → Current Situation (Ribbon tab) → Areas (Ribbon bar) → Add Empty Area (Dropdown)

Adding a new Area to the Project.

A new Area is now added, and selected in the left panel.

The Area is listed.

Its details are displayed in the right panel.

The right panel with details on the new Area.

At the bottom of the right panel, click on "Adjust Area" to start manually drawing it in the Project map.

The option to start drawing the Area.

Draw it in the location of a park or similar recreation area. Ensure that it is somewhat oversized, overlapping with the road network.

A drawn selection of a large point of interest.

When drawn in properly, click on "Apply Selection".

The option to confirm the drawn selection for the Area.

In the right panel, switch to the Attributes tab.

The Attributes tab.

At the bottom of the right panel's list of Attributes, fill in the form for a new Attribute with the following input:

• Name: RECREATIONAL_DESTINATION
• Values: 1

Information for a new Attribute.

Click on "Save New Attribute" to add the Attribute to the Area.

Save the new Attribute.

The new Attribute now appears in the Area's list of Attributes.

The new Attribute is now listed.

With these steps an Area has been added to the Project map indicating a Destination Area we can use with the Travel Distance Overlay.

Configuring a Travel Distance Overlay

Add a Travel Distance Overlay.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar) → Grid Calculation (Dropdown) → Travel Distance

Adding a Travel Distance Overlay.

A Travel Distance Overlay is now added, and selected in the left panel.

The selected Travel Distance Overlay.

With the Overlay selected in the left panel, its details are displayed in the right panel.

The details shown in the right panel.

Click on "Configuration Wizard".

The button to open the configuration wizard.

This opens the Configuration Wizard which will assist in setting up the Travel Distance calculation.

The configuration wizard opened.

Continue to the step regarding Destination Areas (skipping over any intermediate steps if neccesary).

The step for defining Destination Areas.

This step allows for configuring the destinations of the Travel Distance Overlay.

Click on "Select existing Destination Areas based on Attribute".

Selecting Destination Areas based on Attributes.

This will show a dropdown with which to select the Attribute marking the Areas to be used as destinations for the calculation.

The dropdown for selecting Attributes.

Change the dropdown to "RECREATIONAL_DESTINATION", the Attribute previously added to the Area created earlier.

The changed Attribute selection.

Click on "next" in the bottom right of the window to confirm the selection

The "Next" button will confirm the selection.

The Travel Distance Overlay is now configured to find Areas with a particular Attribute. As the Area created previously has that Attribute, this step in the wizard now shows that Area as Destination Area in a dropdown.

The created Area is now listed as a Destination Area.

This has now configured the Area as a Destination Area for the Travel Distance calculation.

Continue to the step regarding Settings (skipping over any intermediate steps if neccesary).

The Settings step.

This step allows for setting the numerical parameters for the Travel Distance Overlay's calculation. There are 2 parameters available, the most important of which is the Max travel distance.

Set the "Max travel distance" to 400 (m).

The travel distance changed to 400 meters.

These are all the configurations needed for a minimal travel distance calculation.

For the sake of insight, continue to the step regarding Traffic Types (skipping over any intermediate steps).

The Traffic Types step.

This step allows for the configuration of which mode of travel should be taken into account for the Travel Distance Overlay's calculation. By default, travel by cars is the selected mode of travel. This is the default because it is the most clear based on default data sources. Any road with cars on it is taken into consideration.

Although it is possible to configure the Travel Distance Overlay to take into account (or use exclusively) any other mode of travel as well, additional configrations elsewhere in a Project will be required to set those up properly. Therefor, it is often more efficient (and a good enough indication) to use cars as mode of travel for a general indication of reachability.

(This relies on the assumption that in urban environments where cars can travel, most car routes are accompanied by routes for pedestrians and bicycles.)

Finish and close the Configuation Wizard.

With the Travel Distance Overlay now configured, click on "Update Now" to let the Project recalculate.

Click on "Update Now" to recalculate the Overlay.

Inspecting the results

The Overlay will show results in the form of a blob, spread out starting from the Destination Area and propagating over the roads, with a buffered distance from the route it has traveled.

The results of the Travel Distance Overlay.

All locations in this blob can be reached from the previously defined Destination Area, and when starting from any of those locations it is possible to reach the Destination Area.

The buffering is so that the end-result of the calculation is not merely which parts of the road network are reachable (or within reach), but that the results actually "hit" the Buildings nearby. This means the results can be used directly to match with specific Buildings and whether those Buildings are in range of a Destination Area.

A close-up of the calculation results. The found routes are buffered to "cover" nearby Buildings.

For one Destination Area result, it will be a single color spread out. When multiple discrete Destination Areas exist, each Area will result in a unique value and coloring, showing which Destination Area is effectively "closest" or "most immediately reachable".

Assignments

1. Add one or more additional Destination Areas to the Project. Remember to configure them with the configured Attribute. Place them in locations distinct from each other and from the Destination Area already present. Recalculate and observe the result.
2. Using the Configuration Wizard of the Travel Distance Overlay, modify the Distance to road setting to a lower value. Recalculate the Overlay, and take note of the effect on the spatial calculation.

Advanced destinations for the Travel Distance calculation

While the basic Travel Distance Overlay setup can perform simple travel distance calculations with static and automatically provided data, it is possible to create more complex and dynamic calculations by using Prequels. The ability to use (pre-)calculated prequels allows for two important additions: the ability to clean up or improve the inputs to handle minor imperfections, and the ability to the fully determine the traversable network or the destinations.

Previously, a Destination Area was drawn manually, specifically overlapping with with the intended point of interest and the network.

However, commonly datasets don't have the same excessive overlap. This can be for a number of reasons. Foremost, points of interest are usually structured as point features. And even when such features are defined as polygons, it is usually an exact fit, and any intermediate feature between the actual Building or location, and the actual road network, is excluded. Both of these situations may result in a distinct distance between the Destination Area and the Traversable network.

To bridge this gap, an Average Overlay can be used. The buffering effect of an Average Overlay allows for "jumping" from the Destination Area and the Traversable network.

Reopen the list of Areas.

Editor → Current Situation (Ribbon tab) → Areas (Ribbon bar)

The list of Areas.

Add a new Area to the Project.

Editor → Current Situation (Ribbon tab) → Areas (Ribbon bar) → Add Empty Area (Dropdown)

Adding another Area.

A new Area is now added, and selected in the left panel.

A new Area added.

Its details are displayed in the right panel.

The second Area's details.

At the bottom of the right panel, click on "Adjust Area" to start manually drawing it in the Project map.

The option to draw the Area in the Project.

Draw it in the location of a point of interest such as a shop, sports-centre, cultural facility or other recreational destination. Draw it such that it is approximately a point-marker within a Building without extending beyond its walls.

A small "point" marker for a Point of Interest.

When drawn in properly, click on "Apply Selection".

The option to confirm the drawn selection.

In the right panel, switch to the Attributes tab.

The Attributes tab.

At the bottom of the right panel's list of Attributes, fill in the form for a new Attribute with the following input:

• Name: DESTINATION_FACILITY
• Values: 1

New Attribute information.

Click on "Save New Attribute" to add the Attribute to the Area.

The option to save the new Attribute.

This will now serve as the marker for a Point of Interest.

Open the Travel Distance Overlay Configuration Wizard, and progress to the step regarding Destination Areas.

The Destination Areas step in the Configuration Wizard.

To change the Areas being considered for Destination Areas, the setting for Destination Areas has to be reset.

Click on "Reset" on the right side of the wizard.

The "Reset" option for Destination Areas.

Opt to select different Attributes for determining Destination Areas, and confirm by clicking "OK".

Opt to select a new Attribute for recognizing Destination Areas.

Change the dropdown to "DESTINATION_FACILITY", the Attribute added to the newly created Area.

Select the new Attribute in the dropdown.

Click on "Next" to confirm the change.

"Next" will confirm the new selection.

Finish and exit the wizard, and recalculate the Overlay.

Notice that with this Destination Area drawn as it is, it only effectively highlights the location where the Destination lies, but the calculation does not traverse the potential routes away from it.

The Travel Distance Overlay result is isolated from the traversable network.

It does still apply the buffering at the end of the travel distance calculation, despite not having traveled.

This can be fixed by automatically creating a "jump" between the Destination Area and the road network.

Add an Average Overlay.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar) → Grid Calculation (Dropdown) → Avg & Interpolation

Add an Averaging Overlay

A new Average Overlay is now added, and selected in the left panel.

The new Average Overlay is listed.

Its details are displayed in the right panel.

The details of the Average Overlay are displayed.

Set the input layer to "Attribute Max Value"

Opt to find the highest value among layers and use that as the value for the calculation.

Set the cell averaging distance to 30 meters.

The averaging distance effects a buffering around whichever sources are defined.

Set the Attribute to "DESTINATION_FACILITY".

The Average Overlay will now look for the Area indicating a Point of Interest.

Open the Average Overlay's Configuration Wizard.

The button to open the Configuration Wizard.

Continue to the "Operator" step.

The "Operator" step dictates how the Average Overlay computes a result.

Select the "MAX" value operator.

The MAX value operator will use the highest value within the defined buffer.

Close the Configuration Wizard, and recalculate the Project.

Take notice of the results in the Average Overlay. Although the source data (the Area) is effectively a point, the Average Overlay extends or buffers the data automatically. Because the operator is set to MAX rather than AVG, the "high" 1 value is used everywhere in the area surrounding the Destination Area.

The Overlay now cleanly buffers the Point of Interest to touch the traversable network.

Reselect the Travel Distance Overlay.

Select the Travel Distance Overlay in the left panel.

Open the Travel Distance Overlay's Configuration Wizard.

The button to open the Configuration Wizard.

Continue to the "Destination Grid" step.

The step for defining a Grid as input for Destinations.

Opt to use a Grid Overlay as input for destinations.

The option to use a Grid Overlay for destinations.

As input Overlay, set the Average Overlay created previously.

Selecting the Average Overlay in the dropdown.

Take note of the "Destination threshold". Cells in the input Overlay with values at or above this threshold are considered (part of) destinations to calculate travel distances to.

The destination threshold defines at which value cells in a Grid Overlay constitute a destination.

Since the Attribute was created with a value of 1, the Average Overlay uses a MAX operator to retain that value across multiple cells, and the default threshold value is also 1, no changes to this value are neccesary.

Close the Configuration Wizard.

Recalculate the Project.

The option to recalculate the Project.

Notice that now, rather than the smaller drawn Area resulting in only a highlighting of the direct environment of the point of interest, the larger highlighted area of the Average Overlay is used, touching the traversable network and as such creating a proper Travel Distance calculation.

Starting from the point of interest, now touching the traversable network, travel distances are calculated.

Note that if you do not see this result yet, the most likely cause is the Average Overlay is using an "Averaging Distance" which is too low to touch the traversable network. If neccesary, increase the cell averaging distance and recalculate again.

With the possibility to connect Grid Overlays to the Travel Distance Overlay to define destinations, increasingly more complex inputs can be created, including the ability to fully calculate destinations on-the-fly.

Assignments

1. Ensure you have the following Overlays:
   1. An Average Overlay highlighting the "DESTINATION_FACILITY", with an Averaging Distance of 0.
   2. A Combo Overlay, using both that Average Overlay as a Grid Input as well as a "LEISURE_CATEGORY_WEIGHT" as an Attribute Input. Set the formula to "GT(ADD(A,@A),0)"
      (Check both inputs and if either of them exist, give an output)
   3. A second Average Overlay which takes the Combo Overlay as input, with an Averaging Distance sufficient to reach the traversable network, and the operator (which has to be set via the Configuration Wizard) set to "MAX".
2. Ensure that second Average Overlay is the destinations prequel of the Travel Distance Overlay. Recalculate the Project.
3. Verify that you now see both the DESTINATION_FACILITY location, as well as any Buildings of the Leisure Categoery, are used as destinations for the Travel Distance Overlay's calculations.

Expanded modalities for the Travel Distance calculation

The routes which can be traveled across as part of the Travel Distance Overlay calculation are known as "traversables". By default, the Travel Distance Overlay only considers roads for cars to be traversable. The exact order of logic is that the Travel Distance Overlay is set to look for the car modality, and when any given Building has an amount of cars traveling over it, that Building qualifies. Cars are the default modality because there is generally a lot of unambiguous information on where cars exist and are or are not allowed.

The Travel Distance Overlay is capable of looking for different modalities insead of (or complementary to) cars. However, this will additional configuration to properly determine which kinds of Buildings are traversable for that mode of travel.

Open the Function Values window.

Editor → Current Situation (Ribbon tab) → Buildings (Ribbon bar) → Edit Function Values (Dropdown)

Opening the Fuction Values overview from the Buildings dropdown.

This window allows for configuring the default values and properties of Buildings, including the amount of traffic for various modes of travel.

The Function Values window.

At the top of the window, set the "Category Filter" to the ROAD Category.

Selecting a Category of Function to filter the view on.

Next, set the "Group Filter" to OTHER_TRAFFIC.

Selecting a group of Function Values to filter on.

These filters ensure the oveview is a compact overview for exactly the values to be edited.

A limited overview of values.

The default overview of Functions does not immediately show all possible Functions. More often than not, Functions should be explicitly added to this overview so they can be edited.

At the bottom of the Function Values window, find the "Add" Option for Functions.

The option to add additional Functions to the overview.

A Function Selection window will open.

The window to select additional Functions for the overview.

Switch to the Roads category, and select all Functions in that category.

Selecting all functions in the Roads category.

Click on "Select" to confirm the selection.

The option to confirm and process the selection.

The Functions are now added to the overview.

The list of Functions has now expanded to include the selected Functions.

For all Functions on which pedestrians could travel, set the "Pedestrians / Hour" to at least 1.

Functions which should allow for pedestrians have adjusted values.

For all Functions on which bicycles could travel, set the "Bicycles / Hour" to at least 1.

Functions which should allow for bicycles have adjusted values.

Change the Category filter to "INTERSECTION", again add all Functions of that category, and configure them with the appropriate "Pedestrians / Hour" and "Bicycles / Hour" vales.

The values set for intersections.

Change the Category filter to "BRIDGE", again add all Functions of that category, and configure them with the appropriate "Pedestrians / Hour" and "Bicycles / Hour" vales.

The values set for bridges.

When all changes have been made, close the Function Values window.

Next, the Travel Distance Overlay can be modified so that it is focussed specifically on those modalities.

Open the Travel Distance Overlay's Configuation Wizard.

The option to open the Confguration Wizard.

Continue to the step regarding Traffic Types.

The Traffic Types step.

Ensure Pedestrians and Bicycles is checked. Ensure Cars and all other options are unchecked.

Pedestrians and bicycles selected as intended modalities.

Close the Configuration Wizard.

Recalculate the Project.

The Travel Distance Overlay results are now different, more closely alligned with the routes for pedestrians and bicyclists.

Newly calculated routes, now on pedestrian- and bicycle traversable routes.

This result can still be improved further. What the calculation does now is consider all pedestrian routes and bicycle routes as "traversable", meaning that who- or whatever is traveling can freely travel on both. A more proper calculation requires looking at pedestrian routes and bicycle routes separately.

Select the Travel Distance Overlay in the left panel.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar) → The Travel Distance Overlay (Left panel)

The Travel Distance Overlay selected.

At the bottom of the left panel, click on "Duplicate".

The option to duplicate an existing Overlay.

There is now a second Travel Distance Overlay.

A second Travel Distance Overlay is listed.

With the first Travel Distance Overlay selected in the left panel, find the "Name" input in the right panel.

The details of the first Travel Distance Overlay.

Rename this Overlay to "Travel Distance (Pedestrians)".

The Travel Distance Overlay renamed.

Open the Travel Distance Overlay's Configuation Wizard.

The button to open the Configuration Wizard.

Continue to the step regarding Traffic Types.

The step for Traffic Types.

Ensure only Pedestrians is checked. Ensure Bicycles and all other options are unchecked.

Only pedestrians are now selected. All other modes of travel are unselected.

Close the Configuration Wizard.

With the second Travel Distance Overlay selected in the left panel, find the "Name" input in the right panel.

The details of the second Travel Distance Overlay listed.

Rename this Overlay to "Travel Distance (Bicycles)".

The Travel Distance Overlay renamed.

Open the Travel Distance Overlay's Configuation Wizard.

The button to open the Configuration Wizard.

Continue to the step regarding Traffic Types.

The step for Traffic Types.

Ensure only Bicycles is checked. Ensure Pedestrians and all other options are unchecked.

Only bicyclesare now selected. All other modes of travel are unselected.

Close the Configuration Wizard.

Recalculate the Project.

The travel distance results are now separated, showing distinct results for pedestrians and bicyclists.

Distinct calculation results will mean the results don't reach as many places.

Note that there may be unintended gaps in the network, preventing the travel distances from propagating properly. For now, if any propagation is visible (especially when the results between the two modalities are different), the results are sufficient.

Assignments

1. Modify the Travel Distance Overlays' settings so that bicycles can travel twice as far as pedestrians.
2. Add a Combo Overlay, with the following configuration:
   • Input A: Travel Distance (Pedestrians)
   • Input B: Travel Distance (Bicycles)
   • Formula: ADD( MUL(GTE(A,0), 1), MUL(GTE(B,0), 2) )
   • Legend: 0 = Nothing, 1 = Pedestrians, 2 = Bicycles, 3 = Both.

Advanced traversables for the Travel Distance calculation

The results of the Travel Distance Overlay are strongly affected by the traversable network. Another benefit of the network of roads and cars is that these datasets usually have a good connective coverage, while pedestrian routes or bicycle paths can commonly be interrupted by road networks. In addition, there can be more kinds of routes allowed for some modalities, such as bicycles which could also travel on roads for cars as long as the maximum allowed speed on that road is low enough. In other words, there can be more ambiguity for those modes of travel.

Out-of-the-box, the Travel Distance Overlay allows for looking directly at the values of Buildings for modes of travel. But like for destinations, the traversables can instead also be determined through a prequel. This allows for great flexibility both to both bridge the gap between the structure of data and the required input for a calculation, but also the on-the-fly calculation of additional potential routes.

The first step is to create a Grid Overlay showing where the network for pedestrians exists.

Add an Combo Overlay.

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

Adding a Combo Overlay.

A new Combo Overlay is now added, and selected in the left panel.

A ney Combo Overlay is listed and selected.

Rename it to "Pedestrian network"

The Overlay renamed.

In the right panel, switch to the "Inputs" tab.

The Inputs tab.

Ensure the input layer is set to "BUILDINGS".

The setting for the layer to obtain Attributes from.

Set Attribute input A to "NUM_PEDESTRIANS".

The Attribute A input now reads the Function Value for pedestrians from Buildings.

Switch back to the "General" tab.

Switched back to the General tab.

Set the formula to "GT(@A,0)"

The formula showing either a value or not.

Recalculate the Project.

The option to recalculate the Project.

This Overlay now highlights the locations of the pedestrian network as a Grid.

A highlighting of the pedestrian network.

Next, an Average Overlay can be used to buffer the routes to bridge the gaps.

Add an Average Overlay.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar) → Grid Calculation (Dropdown) → Avg & Interpolation

Adding an Average Overlay.

A new Average Overlay is now added, and selected in the left panel.

The new Average Overlay listed and selected.

Rename it to "Pedestrian network (buffered)"

The Overlay is renamed.

Set the input layer to "Grid Overlay"

Opt to use a Grid Overlay as an input for the Average Overlay.

Set the cell averaging distance to 5 meters.

5 meters of buffering means gaps of at most 10 meters can be bridged/filled in.

Set the input Grid Overlay to the previously created "Pedestrian network" Combo Overlay.

The pedestrian network is now selected as an input grid.

Open the Average Overlay's Configuration Wizard.

The button to open the Configuration Wizard.

Continue to the "Operator" step.

The Operator step.

Select the "MAX" value operator.

The "MAX" value operator will use the highest value found in the buffer area.

Close the Average Overlay's Configuration Wizard.

Recalculate the Project.

The option to recalculate the Project.

Inspect the buffered pedestrians network, and check whether there are any significant gaps left in the network. If so, increase the cell averaging distance a little bit until the gaps are resolved.

The pedestrian network is now "thicker", bridging the small gaps in the network.

Finally, this new buffered network can be used as the traversable network for the Travel Distance Overlay for pedestrians.

Select the "Travel Distance (pedestrians)" Overlay in the left panel.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar) → Travel Distance (Pedestrians) (Left panel)

Selecting the Travel Distance Overlay for pedestrians again.

Open the Travel Distance Overlay's Configuration Wizard.

The option to open the Configuration Wizard.

Continue to the "Traversable Grid" step.

Selecting the step for the Traversable Grid.

Opt to select a Grid Overlay as input for traversables.

Opt to select a Grid Overlay for the traversable network.

Select the "Pedestrian Network (buffered)"

The Overlay with the buffered pedestrian network is selected.

By setting a traversable prequel, the settings for the traffic types are automatically disregarded.

Close the Configuration Wizard.

Recalculate the Project.

The option to recalculate the Project.

Notice the pedestrian travel distances now cross the gaps that they previously did not.

The Travel Distance Overlay's results are now more expansive, as the traveler can reach more places with the buffered network.

This setup could have also been realized without using the Combo Overlay, but the Combo Overlay allows for more kinds of surfaces to be defined and combined into a total allowed network for pedestrians. By directly using a Combo Overlay for this setup, it becomes easy to add more inputs in the future.

Assignments

1. Create the same traversables setup for bicycles, with a Combo Overlay for the inputs, and an Average Overlay for buffering. Ensure that, to start with, the Combo Overlay only takes into account NUM_BICYCLES.
2. Amend the Combo Overlay for the bicycles network to also take into account roads with low-speed car traffic. Use the following extra settings in the Combo Overlay:
   • Attribute Input B: NUM_CARS
   • Attribute Input C: TRAFFIC_SPEED
   • Formula: OR( GT(A,0), AND( GT(B,0),LTE(C,30) )

Filtering for relevant sources

With a Travel Distance Overlay calculation set up, the result is the locations where it is possible to travel, as well as a buffer around those reached locations to highlight the objects in that range (rather than only the parts of the network itself.

The intent of that buffer is to easily create follow-up calculations, filtering or classifying relevant objects.

The most common use-case for these features is to create insight in whether people have access to particular facilities without having to travel too far. It can vary whether the focus is on specifically people in residences, or whether it is also relevant to take into consideration commercial or public buildings.

Regardless of the exact type of Building to consider, the way to build up these different use-cases is the same, and somewhat mirrors how the destinations and the traversables have been set up as well.

Add an Combo Overlay.

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

Adding a Combo Overlay.

A new Combo Overlay is now added, and selected in the left panel.

The new Combo Overlay is listed and selected.

Rename it to "All Buildings"

The Overlay is renamed

In the right panel, switch to the "Inputs" tab.

The inputs tab.

Ensure the input layer is set to "BUILDINGS".

The BUILDINGS input layer selected.

Set Attribute input A to "SOLID".

The "SOLID" Attribute of Buildings is set as Attribute input A.

Switch back to the "General" tab.

Switched back to the General tab.

Set the formula to "GT(@A,0)"

A formula to show whether there's a value or not.

Add another Combo Overlay.

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

Adding a Combo Overlay.

Rename it to "Buildings within traversable distance"

The new Combo Overlay renamed.

Set Input A to "All Buildings".

Input A is the Grid of Buildings.

Set Input B to "Travel Distance (Pedestrians)".

Input B is the Grid of reachable locations by the Travel Distance Overlay's calculations.

Set the formula to "IF(EQ(A,0),NO_DATA,GTE(B,0))"

If there is no Building, leave the output empty. Otherwise (if there is a Building), determine if it's within reach.

This formula will check where solid Buildings exist. Any place where they do will compute either a 0 or a 1, depending on the travel distance result. All places that are not solid Buildings will not output any value.

Switch to the "Legend" tab, and activate the "Custom Legend"

The Legend tab, and the Custom Legend option activated.

Remove all entries (if any) and add 2 new ones.

Two new empty Legend entries.

Change one of the legend entries as follows:

• Value: 0
• Color: Red
• Text: Out of range

Change the other legend entry as follows.

• Value: 1
• Color: Green
• Text: In range

A configured custom legend.

Recalculate the Project.

The result is an Overlay which shows which buildings are in range of the indicated destinations.

An Overlay which shows which Buildings are in travel range of the specified Point of Interest.

Assignments

1. Modify the Grid Overlay for highlighting buildings such that it highlights only Residences. Use the "Unit Size" function values for this. There are 5 relevant categories.
2. Modify the Combo Overlay to use both pedestrian travel distances as well as bicycle travel distances as input. Apply the same result categorization and legend as done in the assignments for expanded modalities (0 = nothing, 1 = pedestrians, 2 = bicycles, 3 = both)

Tutorial completed

Congratulations. You have now completed this tutorial. In it, you have learned how to create a Travel Distance Overlay, and configure it with flexible inputs to fine-tune its calculations..