LiDar Scanning: Using a ReCap Workflow within Civil 3D
LiDar Scanning has been around much longer than most people think. But one of the biggest issues is the deliverable of billions of points. The other issue I see often is the time and cost associated with modeling the point cloud so you can get it out of your software as quickly as possible. That typically necessitates a non-Autodesk product and can get pretty expensive. However, with the addition of ReCap to the infrastructure tools from Autodesk, these billions of points seem to act like nothing more than a typical AutoCAD® entity, making it much easier for you and your computer to handle.
Figure 1: LiDar scan and BIM model
This article looks at the benefits of using the ReCap engine in order to take your scans from “Field to Finish” utilizing the power of Civil 3D and ReCap. We will also introduce and explore a couple of my favorite add-ons in case you need to take things a step further.
Overview of ReCap
Even if you just use ReCap to import data, save as an RCS or RCP file to be used inside Autodesk products, which will immensely help speed up the insertion and workflow associated with LiDar point clouds.
One of the biggest points of confusion pertains to the different “flavors” of ReCap. Yes, I am sure this will change by next year, but for right now there are three options as follows.
ReCap – Import and view point cloud data with the base version of ReCap. It is available in all Autodesk suites and this may be the only thing you need.
ReCap 360 – Unlock the power of advanced measurement, organization, and collaboration tools. Also transform photos to 3D models with ReCap 360 Photo. The model below (Figure 2) was created from still shot photos from a DJI drone and imported into ReCap 360. No additional work needed, and this is a quick example of the power of ReCap 360.
Figure 2: Drone data capture using ReCap photo
ReCap 360 Ultimate – Speed your workflow and get increased accuracy by utilizing auto-registration functionality and extensive reporting capabilities.
Really the biggest thing to remember is that if you need to register your scans, you need ReCap 360 Ultimate. If you just want to import already registered scans, or files such as LAS, PTS, etc., then just ReCap will suffice.
Typical Scanning Workflow
There are many types of scanners out there—many do the same thing and some have other features that set them apart. The good thing about ReCap is that no matter what scanner you use (for the most part) you will be able to bring that raw data into ReCap.
Regardless of the type of scanner you have, the typical workflow around data capture and point cloud modeling is about the same.
- Scan Planning. Anyone can run a scanner, right? Although the scan portion itself is simple, it does take some time to plan out your field work. I typically start with some sort of scan plan, maybe by taking a floorplan and sketching out my proposed scan location. Maybe think about where you will place targets, if you choose to use them. And then bring that plan to the field so you can supplement and add locations as needed. Trust me, this plan makes life much easier during registration.
- Scanning. Point data is first captured using 3D laser scans of existing structures. Set up your scanner as needed and remember that scanning is LINE OF SIGHT. If you can’t see something from a certain angle, then the scanner probably can’t see it. So make sure you capture as much data as possible to reduce trips back to the field.
- Importing. Autodesk Recap converts the scan files to a proprietary Reality Capture Scan (RCS) format that can be read by other Autodesk programs. This process, called indexing, involves importing raw scan files into Autodesk ReCap. At the start of this process, you can adjust the number of points imported by changing settings for noise, distance from the camera, intensity range, and decimation values. Save the indexed scan files in a Reality Capture Project (RCP) file that references, but does not contain, the files.
- Organization, Cleanup, and Analysis. A number of methods are available to organize the indexed data to remove or hide portions of the point cloud. Create scan regions that you can turn on and off, specify temporary clip regions, turn off or remove scan files, or delete unwanted points permanently.
- Attaching. Indexed scan files and projects can be opened, or attached, in another program to provide realistic context for 3D models.
- Model. You can now choose to model around the point cloud, create points and surfaces from the point cloud, or fully extract a CAD or Revit model from your point cloud. Many options out there—just depends on how far you need to take it.
Then the “fun” part begins. What do we do with those billions and billions of points? First, let’s dive a bit deeper into some tools inside ReCap that will help once we bring it into AutoCAD® Civil 3D®.
Registration in ReCap
Stitching, or registering, your scans together in ReCap is very simple. In fact, ReCap 360 Ultimate has an auto-registration tool I mentioned earlier. This tool can really help streamline your data processing. But be careful, there is no EASY button and you want to verify. Sometimes when you get the greenlight in ReCap it will still be way out of line. So it is good to continue to check your work as you go.
If you choose to skip the auto-registration, ReCap is one of the simpler processes you can find. Once you enter “registration mode,” your screen will be split in two and you will be asked to pick three points on the left, and three points on the right.
Figure 3: Scan registration in ReCap
Once you successfully choose three points, you move on. You can see a report of all scans registered at any time. The scan registration report gives you the following (Figure 4):
Figure 4: Scan registration report in ReCap
Cleanup and Prepare in ReCap
ReCap has many tools that can help make life easier once you bring files into AutoCAD, Civil 3D, or even Autodesk® Revit®. First, you can remove any unwanted points by simply selecting the area and deleting points. That is where I would start first. You don’t want to add unnecessary points to a surface in Civil 3D.
Regions are very helpful when preparing your point cloud to be modeled. Think of Regions as a LAYER. You can select items within ReCap and then add them to a Region. Walls, pipes, and vegetation are all examples of something you may want to put on a separate Region. In Civil 3D you have a Scan Manager that will allow you to turn Regions on or off.
Figure 5: Adding “Regions”
Bring into Civil 3D
If you have a RCS or RCP file, there probably is nothing simpler then bringing that into Civil 3D. Before, we had to bring point clouds in from the Prospector, and go to lunch in hopes that it would be finished when we returned. Now that same file, imported into ReCap, can be brought into Civil 3D in a matter of seconds. Go to the Insert tab of the ribbon on the Point Cloud panel and choose Attach. That is all!
Figure 6: Attach Point Cloud in AutoCAD Civil 3D
Setting Up Field to Finish in Civil 3D
The “Field to Finish” stuff has been around a long time now, although I still see most firms connecting dots and manually processing their survey data. But I will save that rant for another article.
The setup is fairly straightforward. On the Survey tab of the Toolspace, there are just two things you want to take a quick look at.
Figure 7: Survey database setup
Figure Prefix Databases – Expands to display available figure prefix databases. Figure prefix databases enable you to determine the layer on which a figure is drawn by creating a prefix for a group of figure names. These are basically feature lines, but are controlled from the database and your survey codes.
Linework Code Sets – Expands to display available Linework Code Sets, which are used to interpret the syntax of the field codes that are entered into the data collector by the survey field crew. For example, as we pick points and want to begin a new line, we may choose to use BF (Begin Feature) or B. This entire setup takes just a few moments.
From there, we can begin to pick out points from the scan data.
Picking COGO Points
We first want to turn on some different OSNAP options. Go into your OSNAP settings and select 3D Object Snap tab. On the right side of the menu, turn on the items under Point Cloud.
Figure 8: Point cloud OSNAP
We can now select individual points along our scan. You can use the same create point options that you are accustomed to. The only thing to remember is to code them properly. For example, we can begin by choosing the edge of pavement as a feature we want to define. Based on our codes out in the field and the linework code set we just set up, we just need to make sure they match. For our first point, we will use B EOP1, go to the next point and use EOP1 and continue down the line. At the end we will use E EOP1. This is just a quick example, but you will see how easy it is to use a ReCap file and maneuver around to pick points.
Creating Surface in Civil 3D
In 2015, the Autodesk Point Cloud Surface Extraction 2015 extension provided the ability to create a TIN surface from points within RCS format point cloud scan files and RCP format point cloud project files created with ReCap.
You can use the Create Surface from Point Cloud command that is provided in the extension to create a surface from several point clouds, selecting only the areas that you want to include and filtering out non-ground points so they are not included in the resulting surface. You can select areas of point clouds by using window selections, by defining polygon areas, or by selecting existing closed polylines in the drawing.
- In Toolspace, on the Toolbox tab, expand Subscription Extension Manager Autodesk Point Cloud Surface Extraction. Double-click Extract Point Cloud Surface.
- Select a point cloud, or use one of the command line selection options to select an area of one or more point clouds. The Create TIN Surface from Point Cloud wizard is displayed.
Figure 9: Surface from point cloud
In 2016, this extension was built into the software and now provides the same functionality.
- Click Home tab Create Ground Data panel Surfaces drop-down Create Surface From Point Cloud Find.
- Select a point cloud, or use one of the command line selection options to select an area of one or more point clouds. The Create TIN Surface from Point Cloud wizard is displayed.
Helpful Third-Party Modeling Add-Ons
As of right now, there is no Autodesk product that can really compete with any of the point cloud modeling software out there. In time you will want to extract features such as pipes, walls, floors, etc. Below are some examples of available software.
Faro/Kubit – Early in 2015 FARO purchased leading point cloud modeling software called kubit. kubit has been developing field-proven software products to enable and simplify the use of real world objects in CAD applications since 1999.
For users of the SCENE software from FARO, there is now a Surveyor add-on. The Rithm Survey App for SCENE offers CAD drawing and virtual survey functionality directly from the point cloud.
Cyclone – Enables professionals to use point clouds directly, to process them into objects for robust export into CAD (and other applications), and to allow robust import of data from CAD. Cyclone-MODEL has a large, complete, automated set of tools for accurately modeling 3D point clouds as CAD geometry or as meshes for engineering, surveying, construction, architectural, and related applications.
Clearedge/Edgewise – EdgeWise users report an average modeling time savings of 70 percent. And because models created in EdgeWise export to Autodesk Revit as properly specified wall, floor, pipe, duct, conduit, window, or door families, there is no more remodeling or tracing in Revit!
I am sure there are many more out there, but these are a few I am familiar with and have used.
Conclusion
LiDar Scanning, data capture, reality capture, or whatever you want to call it, is here to stay! I could take up 100 pages with survey and scanning workflows, there is just so much to it. But as the hardware and software have drastically dropped in price, I am seeing this become a service that is talked about in even the smallest of firms.
I suggest that if you are debating whether or not to get a scanner, hire it out on the first one, or rent a scanner. That way you can really see what you are able to do before dropping 100 grand. Take the leap on this one—I think you may be surprised.
Good luck and happy scanning!
