Build a Simple 3D City Model In ArcScene (Rachel Oldroyd)

by Rachel Oldroyd, GIS Teaching Associate and Part Time PhD Student. Tweet @r_oldroyd

With the recent release of Ordnance Survey Building Heights data through Digimap, I wanted to write a quick tutorial on making a really simple 3D City Model. You need access to ArcMap, ArcScene and Digimap.

• Login to Digimap (you will need to register to access the service) and visit the Ordnance Survey tab: http://digimap.edina.ac.uk/

• ‘Use Tile Name’ within the Data Download service to download the following data for the tile ‘SE2934’ (this is the University of Leeds Campus but any city will do):

• Once downloaded and extracted, add the layers to ArcMap.

• At this point we are going to clip the Building Heights layer based on the extent of the TIFF layer to reduce processing time. To do this, create a new Vector layer to base the clip on (a vector layer can’t be clipped to the extent of a TIFF). Open the ArcCatalog plug-in from the right hand side of the screen and right click in your working directory, select New>Shapefile and create a new polygon shapefile named ‘clip_extent’ and set the co-ordinate system to British National Grid.

• The newly created layer should add automatically to the map window, then ‘Start Editing’ from the Editor Toolbar (you may have to add the Editor Toolbar from Customize > Toolbars). Select Clip_extent as the layer you wish to edit and select ‘Create Features’ from the Editor Toolbar. Use the Polygon construction tool from the bottom right hand window to draw a square around the extent of the TIFF MasterMap data. Save changes and stop editing.

• Use the newly created clip_extent polygon to clip the Building Heights layer (Geoprocessing > Clip).

• Now the data is prepped, use the ‘Launch ArcScene’ button from the right hand side of the top toolbar to open ArcScene.

• Add the DTM, Building Heights and MasterMap layer to ArcScene and turn off the visibility of the DTM to improve performance when zooming and panning around the map (this is quite a large file).

• We are now going to extrude the footprint of each building to give it a height. Visit the Extrusion tab within the Layer Properties window of the Building Heights Tick the box to ‘Extrude features in layer…’ and in the expression window underneath choose ‘relh2’. This attribute represents the height difference between the minimum base height and maximum roof height of the building, i.e. the relative height. Apply the extrusion by ‘adding it to each feature’s minimum height’ and apply the changes. You should now see a 3D model of Leeds. At the moment the model is sat on a flat surface

• In the Layer Properties tab of both the MasterMap and the Building Heights layers, set the Base Height property to ‘Floating on a custom surface’ and choose the DTM as the surface. The 3D model should reflect the relief of the terrain.

• Right click on ‘Scene layers’ at the top of the Table of Contents and set ‘Vertical Exaggeration’ to 2 in the ‘General’ tab of the ‘Scene Properties’ This will add a slight exaggeration to the scene.

• Fly through the scene using the Bird Icon Button and admire your work (left clicks to go faster, right clicks to slow down).