Author Topic: Digitizing Breaklines (Polylines) in Dense Pointcloud  (Read 3009 times)


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Digitizing Breaklines (Polylines) in Dense Pointcloud
« on: July 29, 2019, 12:46:56 PM »
Hello Photoscan/Metashape Community!

I am trying to create/digitize breaklines in the dense PointCloud.
That way, I can later produce a precise Mesh, where the breaklines are considered.
(I need a mesh from roads where the edges are precise - no trianlges going over the edges...)
However, when I am digitizing polylines in the dense pointcloud, the vertices aren't correctly picked.
I was trying to pick points from several views/directions, but the resulting polyline/breaklines always reside in the air (many centimeters above the actual points).
Is there any possibility to correctly pick points/vertices for the polylines? A sort of "snapping" would be convenient...
I will add some screenshots later to illustrate the problem...

Also: What is the general workflow to produce breaklines in Agisoft? Is there any?
I am testing VS (Virtual Surveyor) in parallel, but I would love to achieve theses tasks directly in Metashae/Photoscan....

Regards, Chris.


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Re: Digitizing Breaklines (Polylines) in Dense Pointcloud
« Reply #1 on: August 04, 2019, 01:42:00 PM »
Hi Chris,

You could try to digitise your breaklines on the DEM and/or orthophotograph instead of the dense point cloud. The DEM and orthophotograph generally show you more detail (more than the dense point cloud or mesh). Note that everything that you digitise in 2D/2.5D will be automatically shown/available in 3D in Metashape. You can even digitise on your original photographs that have been used to compute the point cloud/DEM/orthophoto and you will then see this line 'magically appear' in your 3D photogrammetric model.

Best regards,
« Last Edit: August 06, 2019, 05:50:03 AM by SAV »


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Re: Digitizing Breaklines (Polylines) in Dense Pointcloud
« Reply #2 on: August 05, 2019, 07:09:59 PM »
You can try to create a mesh from dense cloud or from depth maps, texture it and then digitize directly on the 3d model. It works better than trying to digitize in the dense point cloud.


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Re: Digitizing Breaklines (Polylines) in Dense Pointcloud
« Reply #3 on: August 06, 2019, 04:59:49 PM »
Thx a lot for your tips,
Yep, I ended up digitizing the break lines directly on the DEM which worked really well.
After creating the lines I selected them, right-click update heights.
Next question: As of now, I think Metashape doesn't use the vector data (breaklines) for mesh-creation?
Would be great to have an option "use vector layer XXX as breaklines" at the mesh creation dialog.
That way metashape would create accurate Meshs having the triangles line up perfectly at the breaklines.

sidenote: the algorithm of VS (Virtual Surveyor) wasn't very good, also my edges didn't seem to be rough enough
for the algorithm to work correctly. The automatically detected brealines broke up pretty quick or weren't detected along the edge...


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include breaklines (polylines) in meshing process
« Reply #4 on: March 24, 2021, 09:44:46 AM »
Hello guys  :)

i'd like to create a mesh (mainly along sidewalk and road surface) while forcing the triangle creation to stick to pre-defined breaklines.

I really would like to do this in Metashape directly, but there doesn't seem to be a way to include breaklines into the meshing process.
And even if it would work in Metashape another issue comes the "rounded edges" "photogrammetric curve"

Two questions related to this:

1) Do you know any improvements of Metashape with regard to this?
2) Do you have any recommendations for any other workflow?

Thanks a lot, guys.

« Last Edit: April 26, 2021, 06:10:12 PM by toxicmag »
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