City Designer: Creating a City Specification¶

In Ürban PAD, a city simulation is carried out in two steps:

City specification: Creation of a specification, or description of how the city will be generated
City simulation: Launching the simulation from a given specification

Creation of a city specification and launching of a city simulation both take place in City Designer. These steps may take place parallel to content creation with the Editors, or as independent steps.

What Do I Need to Create a Successful City Simulation?¶

You will first need the create the city specification. This page will focus on the specification only.

It may be helpful to think of this document as a “recipe” for constructing the city. In creating your specification, you assemble the various pieces of urban content that you have created with the Editors by adding .gcf files to a central document - the specification.

You will also define interactions between the different pieces of urban content, as in the Activities and Influences parameters.

Next, you save your specification and launch your simulation. The city generator then retrieves the data referenced in the specification and places it according to the rules you have defined.

Do I Have To Define All Specification Parameters?¶

Most city specification parameters have both basic and advanced options. It is not necessary to define advanced parameters in order to launch a successful simulation from a city specification.

To create a basic city specification, you will need:

A Heightfield and Heightmaps
A defined world - see Step 1: Defining a World
At least 1 activity - see Step 3: Defining Activities
At least 1 road template - see Step 4: Adding Road Templates
At least 1 sector template - see Step 7: Defining City Sectors and Step 8: Defining World Sectors

Creating a City Specification¶

The following tutorial will guide you through creating a city specification. A full sample specification can be found in the Ocean Isle City Project, which is available upon creation of a Gamr7 Forum account or upon request of an Ürban PAD trial version.

To access the specification screen, pictured below, click on the City Designer tab once you have opened Ürban PAD and loaded a city project.

Step 1: Defining a World¶

The World parameter allows you to define the sky and sky shape. The choices available for this parameter are static and cannot be changed by your input, unlike the heightmap, which may be added as a file created by a separate application.

Select the sky and sky shape by clicking on the drop-down boxes.

Step 2: Adding an Environment Layer¶

The Environment Layers parameter allows you to restrict activity placement to specific areas of the city map.

An environment layer map is a black and white .png map used to constrain activities to a single area of the city map. You can create an environment layer map with graphic design software and add it to the City Project Folders as one of the maps included in the Heightfield and Heightmaps map folder.

To restrict activity placement on the basis of an environment layer map, you will need to create a relation of influences between this map and the activity whose placement you want to restrict.

A complete tutorial on creating and using environment layer maps is available on the Heightfield and Heightmaps page under the title Optional Step II. The tutorial will teach you how to:

Create an environment layer map with graphic design software
Establish an influence relation between an environment layer map and an activity

To add an environment layer map, right-click on the Environment Layer line, select Add Map, and choose the .png map you wish to add from the file explorer.

Step 3: Defining Activities¶

The Activities parameter allows you to define which activities will be present in your city.

In City Designer, an activity consists of one or more parcel templates created with Parcel Editor. This content corresponds to a .gcf file which can be found in the Parcels directory of the City Project Settings.

An activity may consist of a single parcel, or of multiple parcels grouped together. This is apparent in the photograph below:

Notice that beach consists of one activity template, while office_buildings includes two activity templates.

Adding an Activity¶

To add an activity:

Right click on the Activity parameter
Left click on Add Activity. This will add a line with the title activity_XY, where XY is a number, to the specification. A sub-line will be titled, area_template_XY, where XY is a number.
Click on the area_template_XY line to open the file explorer on the right.
Select a parcel template from the file explorer to add it as an activity.
Repeat the operation for the number of activities desired.

Distribution¶

The distribution parameter is an optional parameter that allows you to define the number of each activity you want in your city simulation. In the picture below, you see that there are 5 shopping centers, 5 beaches, and 1 nightclub, for example:

When you enter the desired number for an activity, it is converted into a percentage of the total activities in the city simulation. The percentage corresponds to the proportion of that activity in the simulation. The total percentage is listed at the top of the distribution interface, although you cannot see the percentage for an individual activity.

When you launch the simulation, the city generator will place activities in these proportions. If the total percentage adds up to less than 100, the city generator will augment the proportion of each activity to preserve the ratio between the activities.

Note that you are not required to specify a number for any of the activities. If no numbers are specified, the city generator will produce from your specification a simulation with random and variable proportions.

Influences¶

The Influences parameter is one of Ürban PAD’s most useful features. You can use Influences to create positive and negative attractions between activities.

This functionality is especially useful for automatically creating areas of urban density. Creating a positive attraction between two activities brings them closer together with a specified intensity and over a specified Range. Creating a negative attraction (or repulsion) between two activities pushes them apart.

The following section contains a brief explanation of intensity and range, as well as how to create an influence.

For a more comprehensive explanation of Influences and a tutorial on using this parameter, please refer to Using Activities and Influences to Group Buildings Together. This tutorial is part of the City Project Tutorial: Ocean Isle.

Intensity¶

Intensity refers to the strength of the influence. It is contained in the range [-99,100]. The closer the number is to either end of the scale (-99 or 100), the stronger the force will attract (100) or repel (-99) other activities.

A negative value signifies a negative attraction, while a positive value signifies a positive attraction. It might be helpful to think of these forces in terms of push/pull (negative/positive).

Range¶

Range is the distance, in grid squares, over which the influence force is applied.

The range value represents the percentage of decrease of the intensity applied to grid squares at a specified range. This is represented by the decrease percentage parameter.

In the example below, an influence rule defined as Building/building with an intensity of 80, range of 3, decrease percentage of 70 means a building will attract around itself other buildings with an intensity of 80 in its square.

This influence will decrease over the range of 1 to 3 squares by 30%. Here, 70 as a decrease percentage value means that the influence will be applied at 70% strength over the specified range. The actual “decrease” in the decrease percentage value will be 30%. At a distance of 4 squares, the influence propagation ceases.

Creating an Influence¶

Complete the following steps to create an influence:

Click on the Influences parameter to access the menu at the right of the screen (accessible by clicking on advanced).
The activities will appear in two identical columns.
Select an activity in the left-hand column, then an activity with which you want to create an influence force in the right-hand column. (The photo above shows a relationship between office_building and office_building.)
After you have selected the two activities, the Intensity and Range fields will appear.
Enter the Intensity and Range values.

You have now successfully created an influence.

Step 4: Adding Road Templates¶

The next step in creating a specification is adding the road templates you have created using Road Editor. Adding them to the specification will allow the city generator to use them during city creation.

To add a road, simply right-click the Road line and click Add Road. Select the road template you wish to add from the file explorer. Repeat the operation for subsequent road templates.

Step 5: Adding Crossroad Templates¶

The next step in creating a specification is adding the crossroad templates you have created using Crossroad Editor. Adding them to the specification will allow the city generator to use them during city creation.

To add a crossroad, simply right-click the Crossroad line and click Add Crossroad. Select the crossroad template you wish to add from the file explorer. Repeat the operation for subsequent crossroad templates.

Step 6: Adding Sector Templates¶

The next step in creating a specification is adding the sector templates you have created using Sector Editor. Adding them to the specification will allow the city generator to use them during city creation.

To add a road, simply right-click the Sector line and click Add Sector. Select the sector template you wish to add from the file explorer. Repeat the operation for subsequent sector templates.

Step 7: Defining City Sectors¶

Define the default sector template for your city by choosing an existing sector template. To access this parameter, click City Sector, click advanced on the right-hand side of the screen, and select a sector template from the file explorer.

Step 8: Defining World Sectors¶

Define the default world sector template for your city by choosing an existing sector template. To access this parameter, click World Sector, click advanced on the right-hand side of the screen, and select a sector template from the file explorer.

Step 9: Defining Road Mapping¶

Road mapping is a functionality currently under development. Enhanced documentation will be available shortly.

Step 10: Saving the Specification¶

When you have finished defining the parameters, save your specification as a .gcf file. You may now use your specification to generate as many cities as you like.