Point Clouds In An Infrastructure Project Part Two

In this second part of the review from our Point Clouds in an Infrastructure Project, I’ll be looking at how Infraworks can help you extract what you need from the point cloud. Yes, I know you can put it straight into AutoCAD, Map 3D and Civil 3D, and I know that you can generate a surface from a point cloud in the latter. But Infraworks will do so much more, and the results are far better.

Now with Civil 3D, it’s very clever and you can cut down a full point cloud to the area you need. You can even set the space between points and use linear or Kriging filtering to get a better result. However, the Infraworks result above is a straight export to Civil 3D. No messing with settings.

Point Clouds in Infraworks

To show this, we just put the whole point cloud straight into Infraworks. It has to be noted that the point cloud we used was already cut down to about a 400m stretch of road, so we didn’t spend the first hour watching it import the LAS files. But that aside, we did no filtering, we left all the trees, buildings signs, passing cars and general noise in.

First Create a model with Model Builder. This is optional given the next step, but could be useful.

Next, make the model more accurate by adding some data from Data.gov.uk. If you want to know all about the mapping and constraint data options for all AutoCAD, Map3D, Civil 3D and Infraworks users, visit my earlier blog and download the white paper, A Guide To Autodesk Infrastructure Data Sources.

Here I added LIDAR Landform data from the Environment Agency (EA) and Buildings from the Ordnance Survey (OS). While I was in there, I decided to see if the road was liable to Flooding, so downloaded Floodzone 3 from the EA too. All free of charge by the way ?

The more up to date and accurate Landform is useful because the Point Cloud doesn’t run beyond the road at the sides. Using this data will make the point cloud line up more accurately with the rest of the model.

Next I added the Point Cloud.

It really is as easy as Drag and Drop but don’t forget to put everything on the British National Grid though.

Now the fun really starts. From here you can create a Terrain Surface. Nothing to see. It just processes it, so go and have a cup of tea. When you’re back, turn on the resultant Terrain surface. In the Surface Layers window drag it to the top of the Ground Surface Group and turn it on.

The next job is optional, but useful if you are making a story board or wanting some nice visuals or creating the start of Your BIM model, this is a nice add. Vertical Feature Extraction.

When Infraworks was processing the Terrain Model, there was an option for Horizontal and Vertical feature extraction. With the Vertical features there are 3 types it currently looks for. Lamp Posts, Trees and Signs. You can then choose each one and decide if the software got it right or you want to change it or indeed, just delete it. It’s not the complete package yet, it will get things wrong, but when it is correct, it scales the feature accordingly. Some things are missing at present. For example, traffic lights but you can see where the developers are going with this.

The next thing we did, was horizontal features. Specifically, Road Markings and Kerb tops. This is again, not perfect, but it’s still useful. The key thing when generating your linework is to make sure you use the correct style. Don’t use the Kerb Top Style on the White Lines for example. The software does look for the specific features based on the style you are using.

What is really good, when you have created the lines, you can view them in a cross section with the point cloud (something we’ve asked for in Civil 3D for a number of years).

If you set it to Intensity, you can see the white lines and adjust the position of the point if it’s not exactly right. A small word of warning though. It can be quite a slow process. You will also find the odd point maybe in the air where there is a lot of noise, but in the main it gets it about right.

You can see in the section view below, the yellow dots are the road markings and the blue dot is the top of the kerb.

Next we can generate transverse lines. These can be exported as a csv file. This can give you accurate levels every 10m say (you choose the interval).

Here is the result:

If you spend a bit longer adding more details like people, cars, you can get it quite close to the real world. Certainly, all the important features are accurate.

In the next post I will talk about where we go from here, moving the model into Civil 3D ready for the new design.