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J. Wallace

Working with Lidar

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Hello

Just wondering if anyone has any experience working with Lidar maps or .las files. I imported a .las file via import>Import point cloud and it worked flaslessly. Now I have over 11 million points...yikes.

Not sure how to move forward with this as I'm hoping to get some contour information out of the file but I'm thinking VW alone might not be able to do this. Any comments are much appreciated. Thanks

lidar.png

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I know that in rhino ( delaunay-triangulation tool ) or rhino + grasshopper, you could make a graphical algorithm that would create a mesh from the points.  Perhaps you can do something similar with Marionette.

 

A quick google search turned up:

-   this open source option:  http://assettocorsamods.net/threads/lidar-point-cloud-to-mesh-tutorial.422/

- or this free solution:  http://gmv.cast.uark.edu/scanning/point-clouds-to-mesh-in-meshlab/

- or sketchup:  https://forums.sketchup.com/t/from-contours-lidar-data-point-cloud-system/42303

- dedicated specialty app:  http://www.vrmesh.com/products/studio.asp

- dedicated high-end specialty app: 

 

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@J. WallaceI have used rhino for Delaunay triangulation to create site meshes.  It was one click operation.  Rhinos trial version should allow 25 saves.  So you might could mesh the points with the trial version quickly.  Biggest unknown forms has to do with mesh size.  I've never run the script on a point cloud that large. But, rhino is good at handling large data sets, so it might do it.

 

you can also send me the data if you want and I can try to mesh it in rhino tonight.

 

@JimWcome to think of it, a Delaunay triangulation command would be a good addition to vectorworks, especially as a quick way to build meshes from point data.

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On 12/09/2017 at 5:32 AM, J. Wallace said:

Hello

Just wondering if anyone has any experience working with Lidar maps or .las files. I imported a .las file via import>Import point cloud and it worked flaslessly. Now I have over 11 million points...yikes.

Not sure how to move forward with this as I'm hoping to get some contour information out of the file but I'm thinking VW alone might not be able to do this. Any comments are much appreciated. Thanks

 

 

Yes I have experimented with getting the LIDAR data into a Vectorworks Site Model. See enclosed snapshot which is of a large area made up of 160,000 + points. I had to get the data converted to a cvs file by the surveyor to use as the source data for the Site Model in Vectorworks. So it is not a point could, rather a Vectorworks Site Model.

 

This did get into some semantics regarding accuracy of using points versus the original breaklines that composed the LIDAR terrain in the first place. From the surveyor:

 

"Even a high density of points is no substitute for breaklines in modelling terrain. We regularly use LiDAR data with an extremely high point density, and find the model not sufficient for detailed design, because the format does not allow for the detection of discrete breaklines. As a matter of course, when generating a DTM, I look over the triangles that a generated and usually have to reverse as many as several hundred on a single model, just to make sure the model matches the ground. There is more to generating a good DTM than making triangles from individual points!"

 

I was surprised at this level of accuracy as the resolution from LIDAR is obviously very high but then again I'm not a surveyor and was only facilitating and experimenting a method of getting the LIDAR data as source data for a Vectorworks Site Model. 

 

In my ignorance he sketched the differences between the breakline and the triangulated DTM which I include. This is probably obvious to you but I needed to be educated about this myself. Note the bit about 'triangles generated across linear features".  Anyway I include this FYI.

 

Cheers,

Peter

 

 

 

13084-CombinedData v2017.png

Breaklines.jpg

Edited by Peter Neufeld
Emphasising "triangles generated across linear features".
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I realise that is the crux of the matter but he did not elaborate other than saying it took a few hours. I do not know his process I'm afraid.

 

Cheers,

Peter

 

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I couldn't figure out how to get lidar into VectorWorks in a usable format. I downloaded QGIS. It is a free program and I knew it could do what I needed to do but just couldn't figure out how to get it done. I finally found this guy Randy Hale at http://www.northrivergeographic.com/services  I gave Randy Hale a call and for only a few hundred bucks he sent me step by step instructions on how to get the job done. I take my lidar data which is in .las format and import it into QGIS. There area  few steps involved to weed out the buildings and treetop shots. I export it out of there as a shapefile. When I import the shapefile  into Vectorworks I have several hundred thousand 3D loci that I can select and create my site model as usual.

 

Randy Hale is stellar. He spent time on the phone with me and made sure I was completely happy with the outcome before he ever sent me the invoice. A few well spent dollars for this tightwad!

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Can anyone help me streamline the process by using Vectorworks to convert the las file into 3D loci? My size job usually ends up with an average of 10,000 loci. I am repeating myself a bit here but currently I download roughly a square mile of lidar data in .las format. I import that into QGIS and tell QGIS to only import the selected classes 2,8 & 9. This eliminates building and foliage shots. Then I export the shapefile which contains the 3D Loci.  From that I can generate my site model.

 

Is there a way to get Vectorworks to import only specific classes of points or weed the out afterwards? Adjusting the "percentage to import" will not help me here. Even if I didn't have to import specific classes I want is there a way to get Vectorworks to convert the .las file into 3D loci?

 

 

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