Tag: Autodesk

This is a bonus article in the Point Cloud series. Click to view: 

Article 1 

Article 2 

Article 3 

With all this talk about decimation and removing many of those original points in the cloud, how does one know if they’ve removed too many points? Here is how I do it. 

• Insert the point cloud into Civil 3D.
• Make a surface from the original point cloud, but only a small subset, so it’s not too big.

• Make a surface from the decimated classification using the same red border as above. This so you can tell how many points are used for each surface within that area. 
• Make an alignment and profile sampling both surfaces and have a look. The blue is the original, the red is the decimated cloud. Some of it is bang on and some of it isn’t. You get to decide if you have decimated too much.

Are there any other ways to decimate that are better? VRMESH and Pix4D are expensive applications that do this, but I have limited experience with them. Civil 3D, however, has one more trick up its sleeve. 

• Make a new surface and paste the original point cloud surface into it. Yes, the big one, but remember that it’s only using the points within the red border. 
• Use the Simplify Surface editing tool. The highlighted number is where you can experiment. The bigger the number, the more points will be removed.

• Sample this new surface in the profile view with the other 2 and compare. The purple profile was created with this new surface. That surface contains about the same number of points as the one created using the decimated cloud from Recap. It is closer to the original.

What does this mean? Is Civil 3D’s Simplify Surface tool better than Recap’s “Intelligent Decimation”? In my experience, I find that yes, it can give me a better result. But not always. Even in this same dataset, there are areas where the decimated cloud is closer to the original. The red line below. 

Here is my philosophy. This works best for me. Your mileage may vary depending on your point cloud. 

1. If a cloud has 80 million points, it is more efficient to decimate it using Recap before it ever comes into Civil 3D. 

1. Decimate in Recap, but maybe not as much as you would like. E.g., if I think  1 million points is the right number for my Civil 3D surface, I will decimate to 2 or 3 million. 

1. After modeling the surface, use the Simplify tool to get the surface down to that 1-million-point mark, or whatever your intended number is. 

Click here to download the sample files. 

Most survey and design firms these days rely on point cloud data to some degree. It is often faster, easier, and safer to survey using aerial or ground-based scanners compared with traditional survey methods. 

“But these clouds clog up my Civil 3D drawing when I make a surface.” You say. I’m here to tell you that they don’t have to! The dataset is always huge, tens or even hundreds of millions of points. When the deliverable is a surface model in Civil 3D, 3 things must happen. 

This is the third and final in a series of three articles outlining how Autodesk Recap and Civil 3D are used to carry out these tasks. Click here for the first article in this series. Click here for the second. 

Task 3: Import to Civil 3D and model a surface. You may already know this step, but since Recap has been used to classify and decimate the points, there is a new task in Civil 3D. 

Once the point cloud has been attached, all the points will show, and it seems logical to go here and ensure that ONLY the decimated points (Key) are visible so we can model the surface using only those points. 

Yes, only the Key points are visible, but when we try to model the surface, Civil 3D is using all 15 million of them, not the 10,000 that was specified during the decimation process. Autodesk is aware of this “defect”. When or if it will be rectified is unknown. 

But don’t fret, there is a workaround. 

Turn on the map Workspace (MAPWPACE) and create a new layer from the point cloud. 

Filter the Key points in that new layer. 

Then create the surface normally. Only the Key points will be used. 

Stay tuned for the BONUS article… Yes, you read that right. There is one more. 

Many contemporary survey and design companies now utilize point cloud data to a certain extent. Surveying through aerial or ground-based scanners is frequently quicker, more convenient, and safer compared to conventional survey techniques.

“But these clouds clog up my Civil 3D drawing when I make a surface.” You say. I’m here to tell you that they don’t have to! The dataset is always huge, tens or even hundreds of millions of points. When the deliverable is a surface model in Civil 3D, 3 things must happen. 

This is the second in a series of three articles outlining how Autodesk Recap and Civil 3D are used to carry out these tasks. Click here for the first article in this series. 

Task 2: Decimate (thin) the data. Reduce the number of points to a number that Civil 3D can use. Attempting to model a surface using 80 million points is an exercise in futility! 

Recap 2024.1 can do this! There are a couple of options; I prefer the second. I like to dictate the number of points that will exist in the decimated cloud. Recap will “intelligently” decimate the cloud so as not to remove too many of the important points. 

If you have any more questions about Civil 3D points clouds please contact us at info@solidcad.ca

There will be a new classification in the Project Navigator. 

And the decimated points will be coloured magenta. 

Click here to download the sample files. And stay tuned for the third article…

Most survey and design firms these days rely on point cloud data to some degree. It is often faster, easier, and safer to survey using aerial or ground-based scanners compared with traditional survey methods. 

“But these clouds clog up my Civil 3D drawing when I make a surface.” You say. I’m here to tell you that they don’t have to! The dataset is always huge, tens or even hundreds of millions of points. When the deliverable is a surface model in Civil 3D, 3 things must happen. 

Unfortunately for you, the reader, you’ll need to wait for the whole story as this is only the first in a series of three articles outlining how Autodesk Recap and Civil 3D are used to accomplish these tasks. 

Task 1: Isolate the ground points. Points that do not fall on the ground such as buildings, trees, and overhead power lines and their poles must not be used to model a surface. 

Recap 2024.1 can do this! It’s easy as there are only a couple of options to choose from. Really, in my experience, the default option is often the best. 

There will be a new classification in the Project Navigator. 

And the ground points will be coloured brown. 

Click here to download the sample files. And stay tuned for the second article… 

If you have any more questions about Civil 3D points clouds please contact us at info@solidcad.ca