Travel Distance Overlay: Difference between revisions

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[[File:Travel_Distance_Overlay1.jpg|thumb|300px|Travel Distance overlay for 500m travel distance to a school (blue arrow), over roads with pedestrian traffic (sidewalks)]]
[[File:Travel_Distance_Overlay1.jpg|thumb|300px|Travel Distance overlay for 500m travel distance to a school (blue arrow), over roads with pedestrian traffic (sidewalks)]]
The Travel Distance [[Overlay]] is a [[grid overlay]] which shows a travel distance from a specific starting point (routing [[Area|area]]). The traffic is split between motorized and pedestrian traffic, based on the road type (roads vs sidewalks). The overlay also uses a fill distance to fill up an area adjacent to the roadways, to connect constructions such as housing. The calculation model behind the overlay is based on the same algorithm as used in the [[Watershed Overlay]].
The Travel Distance [[Overlay]] is a [[grid overlay]] which shows the distance that can be traveled from a certain starting point ([[Destination area (Travel Distance Overlay)|destination area]]). The traffic is split between motorized and pedestrian traffic, based on the road type (roads vs sidewalks).  


The travel distance overlay can be used to visualise the travel distance from certain areas of interest (schools, shops, sports centers, etc), based on the road map in the project area. If we take a school as example, we can visualise which houses (and other buildings), within a range of 20m to a connecting sidewalk, are within a walking distance of 500m from the school of the example.
The overlay also uses an additional fill distance, which allows the result to expand to the area around the accessible roadways, to include accessible surrounding constructions. This allows users to query constructions that are within acceptable distance of cells which are within the travel distance.
{{clear}}
 
The calculation model behind the overlay is based on the same algorithm as used in the [[Watershed Overlay]]. The travel distance will therefore not be the exact travel distance, but the 8-direction [https://en.wikipedia.org/wiki/Chebyshev_distance Chebyshev distance].
 
===Example===
The travel distance overlay can be used to visualize the travel distance from certain areas of interest (schools, shops, sports centers, etc), based on the roads project area. If we take a school as example, we can visualize which houses (and other buildings), within a range of 20m to a connecting sidewalk, are within a walking distance of 500m from the school of the example.


===Keys===
===Keys===
* [[Routing_area_(Travel_Distance_Overlay)|ROUTING_AREA]]
[[Travel_features_(Travel_Distance_Overlay)|Travel features]]:
* [[Destination_area_(Travel_Distance_Overlay)|DESTINATION_AREA]]
* [[Blocked_(Travel_Distance_Overlay)|BLOCKED]]
* [[Blocked_(Travel_Distance_Overlay)|BLOCKED]]


===Attributes===
===Attributes===
* [[Travel_distance_(Travel_Distance_Overlay)|TRAVEL_DISTANCE]]
* [[Model attributes (Travel Distance Overlay)|Model attributes]]
* [[Fill_distance_(Travel_Distance_Overlay)|FILL_DISTANCE]]
* [[Route_cars_(Travel_Distance_Overlay)|ROUTE_CARS]]
* [[Route_pedestrians_(Travel_Distance_Overlay)|ROUTE_PEDESTRIANS]]
 
==Actions==
The following actions are to be taken to work with a basic Travel Distance overlay. We will look at an example overlay based on a school and pedestrian traffic.


===Creating a routing area===
===Grid Prequels===
{| class="wikitable"
It is also possible to provide certain input data as more detailed grid. The following data can be provided as prequel [[Grid Overlay|Grid Overlays]]:
|style="width: 5%"|1
* [[Traversable prequel (Travel Distance Overlay)|TRAVERSABLE]]: Provides an alternative for the traversable grid locations. Overrides the default, which are traversable roads which allow the [[Model attributes (Travel Distance Overlay)|traffic of interest]].
|style="width: 50%"|Have a project loaded in the editor and decide the area of interest of the Travel Distance overlay, a school in our case.
* [[Blocking prequel (Travel Distance Overlay)|BLOCKING]]: Provides an alternative for the non-traversable grid locations. Overrides the blocking features configured using [[Blocked_(Travel_Distance_Overlay)|BLOCKED]].
|style="width: 10%"|[[File:Select_School1.jpg|300px|center|thumb|School selected as example, the blue arrow is added for clarity]]
|-
|style="width: 5%"|2
|style="width: 50%"|Add an area and select to Adjust the area. Draw in the area around the school, ensuring that the area overlaps all adjacent roads. In our example the area overlaps with roads east, west and south of the school. Apply the selection.
|style="width: 10%"|[[File:Routing_Area1.jpg|300px|center|thumb|Please note that the area overlaps all adjacent roads east, west and south of the school]]
|-
|style="width: 5%"|3
|style="width: 50%"|Select the newly added area and select its attribute tab on the right side. Add on the bottom a new attribute ROUTING_AREA, with a value of 1. Save the new attribute. The Area color will be used for the overlay, so pick an appropriate color here too.
|style="width: 10%"|[[File:Routing_Area_Attr1.jpg|100px|center|thumb|]]
|}


===Setting up the overlay===
===Result Types===
{| class="wikitable"
{{result types|suppresscategory=true|allowselflinks=true|
|style="width: 5%"|1
  {{:Distance result type (Travel Distance Overlay)}}
|style="width: 50%"|Add a Travel Distance Overlay. Adjust the grid as desired, 1 meter will give a nice resolution in our example.
  {{:Base types result type (Travel Distance Overlay)}}
|style="width: 10%"|[[File:Add_Travel_Distance_Overlay1.jpg|300px|center|thumb|]]
}}
|-
|style="width: 5%"|2
|style="width: 50%"|On the Keys tab of the overlay, on the right side of the editor, the defaults keys ROUTING_AREA and BLOCKED are already filled in. In more advanced setups, added custom keys ('FOO') can also be selected in the drop down menu for each of these keys.
|style="width: 10%"|[[File:Keys_Tab1.jpg|300px|center|thumb|]]
|-
|style="width: 5%"|3
|style="width: 50%"|on the Attribute tab the following attributes can be adjusted to fine tune the desired outcome on the overlay:
* TRAVEL_DISTANCE
* FILL_DISTANCE
* ROUTE_CARS
* ROUTE_PEDESTRIANS
|style="width: 10%"|[[File:Attribute_Tab1.jpg|100px|center|thumb|]]
|}


==How-to's==
==How-to's==
* [[How to add the Travel Distance Overlay]]
* [[How to create a Destination area]]
* [[Area#Adding, duplicating and removing areas|Adding, duplicating and removing areas]]
* [[Area#Adding, duplicating and removing areas|Adding, duplicating and removing areas]]
* [[How to add and remove an Overlay]]
* [[How to add and remove an Overlay]]
* [[How to edit an overlay legend|Edit an overlay legend]]
* [[How to edit an overlay legend|Edit an overlay legend]]


{{Template:Overlay nav}}
==Notes==
* A likely improvement will be the support of diagonal travel distance, also known as ''octile distance''. Here the diagonal distance between two cells is <math>\sqrt{2}</math> times the cell size, instead of the same distance in all eight directions.
* This method does not take into account driving lane and one-direction limitations.
 
{{Overlay nav}}
{{TravelDistanceOverlay travel features nav}}

Revision as of 13:00, 25 February 2022

Travel Distance overlay for 500m travel distance to a school (blue arrow), over roads with pedestrian traffic (sidewalks)

The Travel Distance Overlay is a grid overlay which shows the distance that can be traveled from a certain starting point (destination area). The traffic is split between motorized and pedestrian traffic, based on the road type (roads vs sidewalks).

The overlay also uses an additional fill distance, which allows the result to expand to the area around the accessible roadways, to include accessible surrounding constructions. This allows users to query constructions that are within acceptable distance of cells which are within the travel distance.

The calculation model behind the overlay is based on the same algorithm as used in the Watershed Overlay. The travel distance will therefore not be the exact travel distance, but the 8-direction Chebyshev distance.

Example

The travel distance overlay can be used to visualize the travel distance from certain areas of interest (schools, shops, sports centers, etc), based on the roads project area. If we take a school as example, we can visualize which houses (and other buildings), within a range of 20m to a connecting sidewalk, are within a walking distance of 500m from the school of the example.

Keys

Travel features:

Attributes

Grid Prequels

It is also possible to provide certain input data as more detailed grid. The following data can be provided as prequel Grid Overlays:

  • TRAVERSABLE: Provides an alternative for the traversable grid locations. Overrides the default, which are traversable roads which allow the traffic of interest.
  • BLOCKING: Provides an alternative for the non-traversable grid locations. Overrides the blocking features configured using BLOCKED.

Result Types

Distance result type (Travel Distance Overlay)

How-to's

Notes

  • A likely improvement will be the support of diagonal travel distance, also known as octile distance. Here the diagonal distance between two cells is times the cell size, instead of the same distance in all eight directions.
  • This method does not take into account driving lane and one-direction limitations.