New 3D Resource Site and CityEngine SketchUp Extension

November 25, 2021

Michael Luubert

This blog post highlights two new resources for creating 3D city models that were developed by the Education and Research group at Esri Canada. One is an extension that allows for the use of CityEngine’s procedural modelling technology in SketchUp and the other is a resource site that includes useful 3D models, textures, and rule packages.

CityEngine SketchUp Extension

The first new resource is an extension for SketchUp that allows users to create models in SketchUp using ArcGIS CityEngine’s procedural modelling technology. The extension was built with the CityEngine SDK and uses CityEngine rule packages to create different types of 3D models within SketchUp, such as textured buildings or urban infrastructure. It can be downloaded here: https://github.com/highered-esricanada/CityEngine-Sketchup-Extension

The extension generates a 3D model from a shape drawn in SketchUp. Some rule packages require a 2D start shape, such as a rule that extrudes and textures a building footprint. Other rule packages may need a 3D form as the initial shape, such as a rule that adds balconies and awnings to a building massing.

Once the start shape is drawn, CityEngine’s procedural rules are applied to the shape. You can choose the attributes of the rule package, such as the textures to use when modelling the building, in the extension’s user interface before you generate the model. You can use existing CityEngine rule packages, or ones that you’ve created yourself in CityEngine in the SketchUp Extension.

The CityEngine Sketchup Extension open in Sketchup with a multi-story building model generated using the chosen attributes.

3D City Model Resources Website

The second new resource is the 3D City Model Resources website. The site is a free resource for people to use when creating 3D city models. The first section of the website, CGA Rules, contains a collection of rule packages with links to preview (demo) the rule in your browser using the CityEngine Web Viewer and to download the rule package from ArcGIS Online. Some of the rule packages also have links to videos of the rule in the CityEngineTV YouTube Channel.

The rule section of the 3D City Model Site showing a few available rule packages in the Building category. There is a thumbnail image for each rule along with a description and links to download the package or view the code, a demo or a video.

Some of the rules contain a “View Code” link which will open a text editor in your browser with the CGA code of the rule. Clicking on keywords in the code will open the CityEngine help to the right of the editor window.

The CGA web editor in the 3D City Model site with accompanying CityEngine CGA help. The rule code is displayed on the left side. When a user clicks a keyword, e.g., texture, in the code, the associated help documentation is displayed on the right side.

Following the CGA Rules section is a Models section where you can preview and download 3D models or textures. The models are organized in categories including Buildings, Props, Street Furniture, Recreation, Infrastructure, and Traffic. A GLTF file of the previewed model can be obtained by clicking the Download link.

The 3D model preview in the Models section of the 3D City Models Site displays a catalogue of models at the bottom and a preview of the selected model at the top.

The textures are organized by surface type, such as asphalt, concrete, metal, rocks, sand, etc. Selecting a texture in one of the categories will display a preview of that texture on sample objects. You can adjust the tile size, bump level and light level in the preview and download the textures for use in CityEngine or other 3D modelling software.

The texture preview in the Models section of the 3D City Models Site displays a catalogue of textures at the bottom and a preview of the selected texture on a plane, a cube and a sphere at the top.

Some of the textures have an S, B, or P indicator on the preview tiles, indicating they include additional complimentary texture maps to the colour map. The S indicates a specular map is available to download, which can be used in some 3D programs to adjust the shininess of different parts of the material. The B indicator represents the presence of a normal map which is used to create the illusion of depth on the material’s surface. Finally, the P indicator signifies that physically based rendering materials are available. This is typically one image called an ORM map, which is an acronym for the occlusion, roughness, and metallic maps that are contained in the red, green, and blue channels of the image. These maps can be used in some 3D programs like CityEngine to render the material more realistically.

The site also contains links to tutorials, videos and other resources – as well as a form where you can submit your own rules that you have uploaded to ArcGIS Online. We would like to increase the number of freely-available rules for CityEngine users to make the site more useful to 3D city modelers like you, so please complete the form if you would like your rules to be included.

I hope these two resources are helpful to you when you are creating your 3D models!

This post was translated to French and can be viewed here.