Generating 3D vegetation in ArcGIS Pro
When it comes to 3D GIS, the most commonly seen objects are generally of buildings, utilities or other infrastructure. But there is one type of feature that makes up a big part of our world: vegetation. Modelling vegetation such as trees is important for performing analyses like spatial proximity, line of sight or shadow impact – investigations that are valuable in fields such as AEC and urban planning. There are several ways to render 3D vegetation in ArcGIS. In this blog, I will show you a simple approach on how to generate these features in ArcGIS Pro, as well as how to share and display them in web GIS.
Why model vegetation in 3D?
Vegetation can be found everywhere on Earth as it exists in both rural and urban settings. As such, it is natural for us to study the spatial relationships between vegetation and the surrounding environments. The 3D modelling of vegetation is essential in many cases due to the benefits it brings. These can include realism and visual appeal, environmental simulation, enhanced location analysis and detailed planning and design. To begin generating 3D vegetation, users can leverage ArcGIS Pro and apply symbols that are part of the style libraries in ArcGIS.
Leverage ArcGIS 3D vegetation symbology
1. Prepare vegetation feature layer
The primary step is to ensure your vegetation data has the right attributes. For example, trees should have important data such as height (usually recorded in feet, but useful to convert to metres), diameter at breast height/DBH (usually collected in inches, but also helpful to convert to metres), genus type, species type and common name. Prior to ArcGIS Pro 3.0, there was a capability called Preset Layers that allowed users to match an attribute with genus names to the corresponding vegetation symbol. From ArcGIS Pro 3.0 onwards, the way to perform this matching requires a different tool as the ability to create preset layers has since been removed.
First, decide which type of scene your data is to be visualized in (global or local), then add it into the scene as a 3D layer. Under the layer properties, confirm that real-world units are being used to render your features. Also, check to see if the elevation has been set to display on the ground.
Prepare vegetation layer attribute information
2. Apply symbology to features
In order to match features to the vegetation symbology, select your layer and bring up the Symbology pane in ArcGIS Pro. First, apply unique values to your features as this will enable the Match Layer Symbology To A Style tool to appear under the hamburger icon. In this tool, you can choose a field or an Arcade expression to pair up with a style that has the corresponding monikers. Make sure that the names in your field (or results from your expression) are exactly the same (case-sensitive) as the symbols. To provide realism, ArcGIS has a 3D Vegetation – Realistic style for you to use. This set currently has 83 models. If there is an unknown vegetation type in your data, consider assigning the “Generic Tree” moniker; for the ones that are not covered by the style, you can designate “Other” as the name.
Esri 3D Vegetation – Realistic style symbols
Once the symbology has been applied, open the Vary Symbology by Attribute view in the Symbology pane and specify the symbol sizes. The size field is the one with the vegetation height values (you can apply an expression to calculate or convert the values if required). Unchecking the Maintain Aspect Ratio option will reveal the width size settings, which you can leverage to indicate the diameters of the symbols. However, there is one key thing to note: if you use the DBH values in your data (which are measured at the stem), the resulting symbology will look unrealistically thin. These values would have to be adjusted accordingly to account for the total widths of the models, which have branches and leaves extending out from the stems. A simple way to bypass this issue is to keep the Maintain Aspect Ratio option on so that the symbols can be rendered proportionally based on height.
Use the attribute information to specify the size of the 3D symbols
3. Share to web GIS
Prior to sharing to web GIS, review all desired layer properties and configurations. Pay attention to the coordinate system. If you wish to view your features on top of a basemap in ArcGIS Online or Enterprise, consider using the WGS 1984 system. If the data has a local system (e.g. in UTM), it can be presented in a local web scene, but a basemap and a terrain model with the same local system will have to be prepared separately and added to the scene if required. Under the map properties, check the box on the Allow Assignment of Unique Numeric IDs for Sharing Web Layers option. Right click on the layer, select Share As Web Layer, and review all relevant options. The time it would take to complete the caching is dependent on the amount of data you have. As a best practice, always review any potential errors before publishing by using the Analyze button. This method of publishing is known as creating a scene layer with an associated feature layer, which permits frequent changes (by way of updating the associated feature layer and then rebuilding the scene layer cache) while enabling a fast display of a large number of vegetation points on the web.
Sharing as a scene layer with an associated feature layer
Produce point scene layer content
If your data does not need to be updated often, another approach to sharing your features is to build a point scene layer package. This package is a single file that contains cached 3D content, and it is designed to present and distribute this content efficiently across different ArcGIS applications. Open the Create Point Scene Layer Content tool and use your symbolized vegetation layer as the input. Once the package is created, you can either add it to the Contents pane in ArcGIS Pro and share it as a scene layer or add the package directly to ArcGIS Online or Enterprise as an item and allow it to publish the scene layer. It is important to mention that although the scene layer package is effective for performance and scalability, it is a cache and therefore cannot be edited. If updates are applied to your source vegetation data, you will need to perform this workflow again.
Creating a point scene layer package
Other methods for generating 3D vegetation
A LiDAR or photogrammetric point cloud is regularly used to model vegetation due to its spatial accuracy (especially in the case of LiDAR). If you are managing a point cloud in which the vegetation has not yet been properly classified, you can do so manually or employ a deep learning model, then apply a filter to show only the vegetation classes. ArcGIS Pro supports the ingestion of point clouds in the LAS, zLAS, LAZ or LASD format, but to render them in a web scene, they must be converted into a scene layer package and then published as a scene layer. Leverage the Create Point Cloud Scene Layer Content tool to accomplish this.
Classified point cloud web scene layer showing vegetation
The Tree Management Solution is an industry-focused configuration that is deployable from ArcGIS Solutions in ArcGIS Online or Enterprise. It delivers a set of capabilities for users to establish and maintain an inventory of public trees, which are considered local government properties. A part of the solution provides workflows to classify, extract and/or load vegetation locations and attributes from available LiDAR or existing feature data and then display them in 2D and 3D apps.
The Tree Management Solution includes a 3D scene to visualize vegetation
Another way to build vegetation models is to utilize ArcGIS CityEngine. The ESRI.lib vegetation library is automatically installed with CityEngine and it contains rules and assets for users to procedurally create vegetation based on feature attribute information.
Vegetation assets from the ESRI.lib library in ArcGIS CityEngine
Vegetation makes up a significant portion of our world. Developing 3D representations for these features is therefore often a requirement for endeavours such as digital twin design and construction. There are several ways to generate 3D vegetation in ArcGIS. Choose the method that fits the best with your project goals and data governance!
3D vegetation models offer appeal and enable visual analysis