Exploring 3D Surfaces
Before tackling this tutorial, you will need to download and install a dataset following these instructions:
Create a folder called surface3D somewhere under your personal directory (e.g. C:\Users\jdoe\Documents\Tutorials\surface3D\).
Download the surface.zip data for this exercise then extract the contents of surface.zip into your newly created surface3D folder.
Open the map project
Open the surface.aprx file.
The project consists of a single raster layer and a background Topographic map. The raster layer consists of a grid of surface elevation values derived from LIDAR data. The raster file was downloaded from USGS’ National Map website.
The elevation layer covers most of Colby College's campus and includes obstructions such as trees and buildings.
While our mental interpretation of the data may be three dimensional, the Map view treats the raster as a two dimensional layer with each pixel representing an attribute value. In the next step, you will learn how to generate a 3D surface from this raster layer.
Creating a 3D scene
In the Insert ribbon click on the New Map button and select New Local Scene.
This action will add a new tab named "Scene" to the current GIS project.
You'll note that the Contents pane differs from that of the Map view. It has three distinct groups: 3D Layers, 2D Layers and Elevation Surfaces. When you add a layer to a 3D Scene view, you need to specify which layer group it should be assigned to. By default, ArcGIS adds the familiar World Topographic and World Hillshade layers to the 2D Layers group.
At first glance, the 3D scene view looks no different from the Map view. You can zoom in and out as you would in Map view. However, this view has tilt and rotate options that allow you to navigate the map in 3D space.
To navigate the 3D scene making use of the mouse as described below, make sure that you are in Explore mode (found under the Map tab).
Left mouse button: Press and hold to pan around the map
Middle mouse button: Press and hold to tilt up and down and to rotate map.
Right mouse button: Press and hold to zoom in and out
Scroll middle mouse wheel: Use to zoom in and out
Zoom in to a mountainous area of the earth's surface. In this example, we are zoomed in on Mount Katahdin (Maine, USA).
You'll note the 3D topography embedded in the view window. The topography is provided from the WorldElevation3D/Terrain3D layer that is part of the default layers added to the 3D scene view. This layer is associated with the Elevation Surfaces layer group. While this layer may be suitable for small scale (i.e. large extent) analysis, it may not provide the level of detail necessary for a large scale analysis. In the next step, we will use the Colby campus elevation raster layer to generate the 3D surface.
Creating an elevation surface from a custom elevation raster layer
Right-click on the Ground element under the Elevation Surfaces group and select Add Elevation Source.
Select the Surface.tif raster from the project folder then click OK.
If you are asked to create a Pyramids file from the Surface.tif raster file, click on the OK/Yes button.
Uncheck WorldElevation3D/Terrain3D layer.
If you are not automatically zoomed in on the Surface.tif layer, right-click on Surface.tif and select Zoom To.
The Surface.tif raster now serves as the 3D surface layer unto which layers listed under the 2D Layers group are draped over. Currently, the 2D layers consist of the World Topographic Map and the World Hillshade layers.
Next, we'll turn off the 2D layers to help us better view the elevation surface generated from the Surface.tif raster.
Uncheck ( turn off) all layers under the 2D Layers group.
Doing so may render the Scene view blank, or so it may seem that way. Next, we'll apply shading to the 3D surface to render it visible in the view.
Select the Ground item in the Contents pane.
This will display the Appearance tab in the ribbon. If you are working with ArcGIS Pro 3.0 or later, you will see the Elevation Surface Layer tab instead.
In the Appearance ribbon (or the Elevation Surface Layer tab if working with ArcGIS Pro 3.0 or later), check Shade Relative to Light Position.
Change the Surface Color to a shade of grey (or any non-white color).
At this point, a faint outline of some of the surface features should appear in the view.
Using the mouse, tilt the scene back. Doing so will change the 3D feature's angle relative to the light source in the scene. Doing so will reveal many of the campus' features.
The scene converts the raster layer's pixel values to elevations. It is therefore important to note that to maintain proper scale, the pixel values should be in the same units as the underlying coordinate system's XY units. In this example, the units are meters for both the XY plane and the elevation values.
If your raster layer's pixel values are in a different unit than that of the XY plane units, you need to modify the vertical units in the raster layer's properties (accessible by double-clicking the raster layer used as the elevation surface).
Draping 2D features over the 3D surface
Any layer added to the 2D layers group will be draped over the elevation surface. In the next step, you will add a vector layer of campus buildings to the Scene.
Add the Buildings shapefile to the 2D Layers group. You can do so by dragging and dropping the Buildings.shp from the Catalog to the 2d Layers group.
If you inadvertently add the layer to the 3D Layers group, simply drag it from the 3D Layers group to the 2D Layers group.
The 2D vector layer will be draped over the Surface.tif layer. Note that the building's shapefile features cover an extent greater than that of the Surface.tif raster layer however, only those features that overlap the Surface.tif's extent will be displayed.
Displaying elevation profiles
Elevation profiles can be created in either Scene View or Map View. Elevation profiles can be generated from existing polyline features or they can be generated by sketching the profile transect lines in the Map or Scene view window. If you opt to sketch the transects manually, it may be easier to do so in Map view mode instead of Scene view mode. In this exercise, we will generate elevation profiles in Map view.
Note that generating a line transect in Map view requires that an Elevation Source be explicitly defined (i.e. simply having an elevation raster loaded in the Contents pane does not make the Map view "elevation surface" aware). We will therefore need to define the elevation source in Map view before proceeding with the profile sketch.
Adding Elevation Surfaces to the Map view
Switch view from Scene to Map.
Note that the Contents pane in the Map view does not automatically reflect that of the Scene view. In other words, any layers added to the Scene view is not automatically added to any other views in the map project.
In the Map tab, click on the Add Data pull-down menu and select Elevation Source.
Select the surface.tif raster when prompted to select a file.
You should now see an Elevation Surfaces group added to the Contents pane. Recall that you created a similar group in 3D scene.
Generating elevation profile
In this next step, you will manually sketch the transect from which an elevation profile will be extract from the surface.tif surface raster.
Click the Analysis tab.
In the Analysis ribbon, click on the Exploratory 3D Analysis tool and select Elevation Profile.
This should bring up the Elevation Profile pane. Make sure that the Interactive Placement option is selected.
By default, the profile will adopt units of feet for the x-axis. You can modify the x-axis units from the Distance Units pull-down menu.
Note that if you were to use an existing polyline feature to define the profile transect you would opt to click on the From layer option.
Zoom in on the Miller lawn area of the college campus
Draw a transect as shown in the accompanying figure. To complete the transect, double click on the last point or press the F2 key.
An Elevation Profile pane should appear near the bottom of the window. The elevation profile is interactive in that hovering over the profile plot will highlight the matching location along the transect.
You can interactively move the transect vertices and see the changes reflected in the profile window. But note that closing the profile window will remove the transect.
You can export the profile to an image or a CSV table by clicking on the Export Graph icon.
This ends this tutorial.