distance between powerline (line feature) and ground (pointcloud)

AlexW

Dear Global Mappers 😃👋

i am working on a pointcloud (photogrammetry from an aerial capture).

Now i am looking for an elegant way to measure the distance between the powerline (which is a line feature) and the ground underneath to get the slack.

I already did the "advenced feature creation" to get a line of points along the powerline. Then i used the Lidar QC tool. But i am still looking for a "more visual" approach rather than just a list of RSMEs. Something like the path profile tool to get a side-view and measure manually.

Any ideas?

Thanks

Alex

946

My example is with just one line but you can do for as many as you have.

1- Create Points From Your 3D Line and put the points on a new layer (Z TOP)

2- Select the points , Copy and paste to a new layer (Z GROUND)

3- Use the DTM or the Ground LiDAR class to apply elevations to points from the second layer (Z GROUND)

4- Select all the points and Create Lines From Selected Points (it will create vertical lines)

In my example, with blue you have the points from the line and with orange their projection on the ground.

By creating vertical lines you have the 3D length for each projection couple.

5- Results:

You can sort by Lenght_3D and you will have them ordered by vertical distance witch is what you need .

You can delete unnecessary or manipulate as you wish, you don't have to manually measure.

946

1.Take the points from line with corresponding Z values.

2 Do a copy layer of this points and add ground value as elevation.

3 Select all points and go to Advanced Creation and create line from Selected points. Use 1cm allowed distance.

AlexW

Hi 946,

thanks for your quick reply.

Could you please explain the steps a little more detailled? I'm not quite getting the point (sorry, not a native speaker).

The powerlines are represented in 9 line features (see box with layer attributes) and so they are not visible in a path profile and so on. All i could do so far is to create points along the line and compare them to the pointcloud underneath.

Frankly, i cannot repeat your workflow. Will it lead to the result i am looking for?

Best

Alex

AlexW

This is pretty cool, 946 :)

I will repeat it as soon as possible. Thanks a lot.

Honestly i don't quite getbthe point why Blue Marble differs so strictly between "points" and "3d points" (like the pointcloud itself).

It would be so easy to create points along the line and watch them in a path profile together with the ground.

Best

Alex

946

But that you ca do :

Make sure you have this box checked and after that right click where you need the point inside profile view and create the point