Tutorial: 3D Modelling and Scanning

SketchUp, ArcGIS CityEngine and iPhone LiDAR

SketchUp – What is it and what do you need?

SketchUp is a 3D modelling program that at the time of writing came (summer 2024) in four licensing (and therefore pricing) options:

• SketchUp Free
• SketchUp Go
• SketchUp Pro
• SketchUp Studio

Each level comes with a set of features and/or limitations depending on your perspective. Yes, there is currently a free version (as in no cost to you) but it is a web only interface and limited to non-commercial projects. For most professionals I would initially recommend the SketchUp Pro version as it allows for additional plugins to be installed to extend the desktop applications functionality. Historically there has been a large community of third-party contributors who using SketchUp’s Ruby scripting interface have added functionality or workflow assistance which can often be a life saver for Architects and Planners.
This author has SketchUp Studio which allows for use of point clouds in SketchUp so you can use that to digitise from.

For the tutorials in this section we will be using SketchUp Pro 2024 for the desktop, you maybe able to follow along using the SketchUp web version (Free or Go) in places.

If you are a student or work in an educational setting, you might have access to this through an educational licence. Working in a private organisation? Try asking your IT team.

The following tutorials assume some knowledge of digitising in SketchUp and a familiarity of navigating in 3D using a mouse. If completely new to SketchUp I would suggest the following resources:

• Getting Started In SketchUp https://help.sketchup.com/en/sketchup/getting-started-sketchup
• SketchUp Campus https://learn.sketchup.com/

Creating your own georeferenced buildings.

This is not your normal tutorial, this is more focused on creating digital twins of urban areas, rather than singular detailed architectural models. Although you can add as much detail as you wish, for this tutorial we are aiming for a simple level broadly in line with Level of Detail 2.0 to 2.3 ()

Step One Start and Setup

Double-click you SketchUp icon and you will be greeted with this screen:

Now here under ‘Create new model’ I generally choose Simple and Meters (you can also see the heart icon which denotes it as the default), but there is more choice! Mostly these templates deal with background colours and display of axes, SketchUp person etc the important thing is to get your unit of measurement correct, but I would not worry too much. If you did get your measurement unit incorrect here you can change it later if required.

Step Two Locate your model

Once SketchUp is loaded you will be greeted with a screen very much like this, it may depend on whether it has been loaded before so toolbars and sidebars position and sizes may vary according to screen resolution.

We are first going to locate our model somewhere, in this case it will be Lancaster City in the United Kingdom. Go to the File menu and click on ‘Add Location’

Next in the Add Location dialogue box click in the search box and type Lancaster, make sure you then click on ‘Lancaster, ENG, GB’!

The map will now change to this, which you will notice is Lancaster, in the UK.

We are actually choosing a building in a place called Morecambe, called the Midland Hotel and iconic Art Deco hotel. This is located on the coast by a distinctive promontory and pier and adjacent to the soon to be developed Eden (https://www.edenproject.com/new-edens/eden-project-morecambe-uk). Zoom in with your mouse using a combination of left click to pan/drag on the map and scroll wheel on your mouse to zoom in. As you do so a message will appear on screen asking whether you location is correct (see Figure 8), ignore this until you have zoomed in enough to get a clear picture of the Midland Hotel.

When zoomed in enough you can click on ‘Move location pin to this area’, move the location pin if required, I personally move this to bottom left of my site, see Figure 9. Once happy click on the blue ‘Continue’ button in the bottom left hand corner of the dialogue.

On the Add Site Context screen, you can decide on whether you want satellite imagery or street map as your basemap, I prefer satellite imagery but it really depends on what you are trying to do. Bing or Digital Globe can be chosen as your imagery provider in this case Bing is a better quality for me. Keep Mesh density and resolution high, but if you are doing large areas you may want to adjust this down to keep it manageable!

Using the blue box handles move/scale/adjust your box to fit the Midland Hotel and then click on the blue button in the bottom left hand corner titled ‘Import Site Context’, you may have to zoom and pan out as well to do this. You will see I’ve included some of the adjacent landscaping here.

Wait for the data to import and click close on the import successful dialogue box after reading it of course!

Now you have your project successfully located with satellite imagery and terrain imported. Zoom out in SketchUp (scroll wheel) and use the pan controls (middle mouse button and hold the left shift key) to view more of your model.

Then of course Save your model! Go to File menu and click ‘Save As’ and place it where you can remember to find it again (often mine will go in special project folders). I’m calling this model ‘MidlandHotel.skp’.

Step Three Prepare and Digitise

Note how once saved the title bar of Sketchup Changes to “MidlandHotel– SketchUp 2024”.

To help digitise along set axes it often helps to move the red, green and blue axes to the building edge you are working on to do this ‘right-click’ on one of the axes (I tend to go for the blue axes as there is nothing behind it) and click on ‘place’ Figure 15.

Move this axes to a corner of the building you are working preferably one that has a right angled corner, see Figure 16.

Using the drawing lines tool and the 2-point arc tool for the curved parts carefully digitise the footprint of the hotel.  Close each polygon you make so there is a white surface shown, you will see some flickering as satellite image and polygon surface clash for attention, this is called Z-fighting where there are two coincident surfaces and the graphics card can’t decided which to draw first.

If you can break the building up in to separate parts which are at different heights.  If you can not see this on the satellite imagery, I recommend view the building in Google Maps either in 3D view or StreetView.

If you require extra information such as building heights (that cannot be gathered from onsite measurements) you might need Google Earth Pro (https://www.google.com/earth/about/versions/ ), using the 3D path tool to measure heights from ground.  Both these methods (Google Maps and Google Earth) require sufficient coverage from Google of 3D buildings, this is not worldwide so depending where you are trying to create buildings this information may not be available.  However the following tutorial on SketchUp using a technique called photomatch maybe an option for you.

Once a footprint with sufficient detail is digitised you can use the Push/Pull  (Figure 21) tool to drag up each building element to the right height. 

Don’t worry if it is not 100% accurate and sometimes you may have to do a best guess.  This really depends on your use case and time constraints!

Slowly go through each surface to extrude till you get a complete model.  As this is a diagrammatic geospatial model we do not need to colour it.

Step Four Group and Save

Once finished it is best to ‘group’ all the geometry you have created together using the select tool select all elements of your model and right click on it then select ‘Make Group’

Step Size Export as KMZ

Now save the model and then click on File  Export  3D Model and save this model as a KMZ where you can find it again.

This KMZ can then be viewed/imported into Google Earth Pro, ArcGIS CityEngine, and ArcGIS Pro, which we will discuss in later tutorials.

Bibliography