The Schematic Local Government Scene is a LOD2 (Level of Detail) 3D scene that includes the World Topographic Map draped over detailed elevation along with LOD2 buildings, building floors, and trees. LOD2 building models have standard roof structures and can be generated in a semi-automatic way. High density lidar and manual building footprint segmentation are needed to model complex roof structures. Buildings and trees in this scene can be generated with classified lidar (ground with first and preferably last return).
Create 3D layers
To create 3D layers used in the Schematic Local Government Scene, complete the following steps:
- Start the ArcGIS Pro application and open the project package from the active portal.
- In the Catalog pane, expand Maps and double-click on Local Government Scene to open the scene.
- If you haven't done so already, sign in to your ArcGIS organization and set as active portal.
- In the Catalog pane, expand the Tasks folder, then double-click on the Publish Schematic Local Government Scene task. In the Tasks pane, expand the Publish Elevation Surface group task to create a DTM (Digital Terrain Model), DSM (Digital Surface Model) and nDSM (Normalized Digital Surface Model) with lidar data. Optionally, you can modify the DTM so the buildings will sit correctly on the surface. When creating the DTM and DSM, enter the following:
- In the Create LAS Dataset step, define the coordinate system for the LAS dataset.
- In the Extract Elevation Surfaces from LAS Dataset step, specify the minimum height below the ground and maximum height above the ground when classifying noise. Visually inspect your LAS data and set the minimum and maximum height for noise, in other words, points that are not buildings, trees or elevation (such as birds). These points should fall outside the minimum - maximum range.
- Expand the Extract Building Footprints group task to optionally extract building footprints from lidar. This is not required if you have an accurate footprint featureclass.
- Expand the Preprocess Buildings group task to optionally preprocess the building footprints. Some building footprints may contain several different roof types and roof parts. To accurately represent these buildings, they need be split into their separate parts. Building footprints can be split with another feature class or by differences in elevation. In Split Buildings using Features, enter the following:
- Split Features—These are the features that will be used to split the building footprints. This can be any polygon features class for example parcel boundaries which can sometimes delineate differences in height and/or roof types between properties especially in dense urban areas.
- Minimum Split Area—This is the minimum area for features that you wish to keep. Features with less area that the minimum area will be ignored in the output.
- In Segment Buildings using Elevation, enter the following:
- Spectral Detail—This is the level of importance given to height differences in your DSM. Valid values range from 1.0 to 20.0, with higher values corresponding to more sensitivity to height differences.
- Spatial Detail—This is the level of importance given to the proximity of features in your DSM. Valid values range from 1.0 to 20.0, with lower values providing a smoother output, and higher values providing more individual segments.
- Minimum Segment Size—This is the minimum size of a segment of the DSM in pixels. This will default to a size of 50 sq meters based on the cell size of the input DSM.
- Regularization Tolerance—This is the maximum linear distance that segment polygons can be adjusted in the effort to regularize geometry to right angles and diagonals.
- Segment Flat Roofs Only—Leave this option off when preprocessing the building footprints. Optionally you can decide to run this tool again after building creation to further refine the flat roof segmentation. In that case you would turn it on.
- Expand the Publish Schematic Buildings group task to publish a 3D building layer. In the Create Buildings step, enter the following:
- Minimum Flat Roof Area—This is the area threshold at which a flat (less than 10 degrees) planar surface is considered an architectural facet of interest.
- Minimum Slope Roof Area—This is the area threshold at which a sloped (greater than 10 and less than 70 degrees) planar surface is considered an architectural facet of interest.
- Minimum Roof Height—This is the minimum height above ground for a planar surface to be considered a roof plane (based on input nDSM).
- Simplify Tolerance—If you selected to simplify the building footprints, this is the tolerance that determines the degree of simplification for example, the maximum allowable vertices offset.
- Run the Review Building Roof Forms task to analyze the Roof-Form Extraction process results and inspect your building roof forms.
- Use the Modify Roof Form tools to further improve the quality of the building roof forms.
- Save your edits and publish the schematic buildings, using the Publish Buildings step.
- Click on the Update Schematic Buildings task to update an existing LOD2 multipatch building layer if new lidar is available. When detecting changes, enter the following:
- Vertical Change Threshold—The maximum allowable vertical difference between lidar and building multipatches before being flagged as a change in the buildings.
- Minimum Area of Change—The minimum area required for a discrepancy in height between buildings and lidar to be flagged as a change area.
- Analysis Cell Size—The cell size of the surface rasters used to compare lidar and the buildings. Typically this should be set at the average point spacing for the lidar data.
- AOI—The area of interest for the change analysis. This should be a polygon that covers the buildings that you wish analyze.
- Replace Changes—If checked, this keeps the new footprints that were created incorporating the changes in geometry. If unchecked, the tool will preserve the original footprints of the changed buildings.
- Click on the Publish Schematic Trees task to publish a 3D tree layer. When creating the 3D trees, enter the following:
- Pointspacing—The average point spacing for the lidar data. This can be found in the LAS dataset properties.
- Vegetation class codes—The correct class codes for vegetation. If the vegetation has not been classified, enter the class code that represents the vegetation, for example, 0 or 1.
- Buffer distance—The buffer distance so building and other overhanging features do not impact the calculated height of the trees.
- Minimum and maximum canopy height—The minimum and maximum height of vegetation in the community.
- Expand the Publish Building Floors group task to publish a 3D Building Floor layer. In the Create Building Floors step, enter the following:
- Buildings—The multipatch feature class that represents the buildings. These can be schematic buildings created by the Publish Schematic Buildings task or 3D buildings that come from another source.
- Choose to Split By Building Space Use Table, or Split by Floor Parameter such as number of floors, ground floor height, upper floor height, and roof height.
- Enter the Minimum Floor Area, Splitting Sensitivity, and XY Tolerance.
Author Schematic Local Government Scene
To author a Schematic Local Government Scene, complete the following steps:
- Sign in to your ArcGIS organization.
- Create a Scene using the 3D layers and elevation service you published.
- Optionally, add other web feature layers to your Local Government Scene.
- Save the scene as Schematic Local Government Scene and share it with your organization.
- Begin using the Schematic Local Government Scene.
Once you have finishing publishing your scene, you can also share it with the Living Atlas.