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Importing points using depths from OGL

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Message 1 of 10
wilsonm2000
1341 Views, 9 Replies

Importing points using depths from OGL

Hi

 

We have a points file to create a "bottom of peat level" surface.  The only problem is, along with the X and Y, it only gives us the distance from OGL, not the actual Z Elevation at each point.  How do we import these into C3D to create a surface?  We have a topo survey for the whole site, so we have and EG surface.

 

Cheers

Martin

9 REPLIES 9
Message 2 of 10
wfberry
in reply to: wilsonm2000

Perhaps you can get the "distances" in your point file as descriptions with "0" elevations.  Once in the drawing you can have them "hop" to the Ex. ground elevation of the surface.

 

OK, now you are on your own.

 

Smiley Happy

 

Bjill

Message 3 of 10
wilsonm2000
in reply to: wfberry

Hi berry

 

sorry, I dont understand how I would do that. 

Message 4 of 10
IanMcClain
in reply to: wilsonm2000

What is OGL?

Ian McClain
Message 5 of 10
wilsonm2000
in reply to: IanMcClain


@IanMcClain wrote:

What is OGL?



Original Ground Level

Message 6 of 10
wfberry
in reply to: wilsonm2000

One never knows about the experience of the person asking questions without some guidance.

 

I am assuming you know how to import your points into the drawing.

1.  I always insist that when importing points that you have set up a point group for them.

2.  Once these points are inserted and are happily appearing in your group, select the first row (or any row) and use the Ctrl key and the A key simultaneously.  All the points are selected.

3.  Right Click this highlighted group in the window and select "Elevations from surface".  All points are given the elevations at that location on your surface.

 

Now all you have to do is subtract the distances in your description to get the elevation you desire.  Maybe export points out and correct in Excel, import back in.

 

Bill

 

Message 7 of 10
wilsonm2000
in reply to: wilsonm2000

Great, thanks for that.  I know how to do all those steps, its the "subtracting the distance in the description" I do not understand, how do I get each point to move according to the individual descriptions?

 

Thanks again for your help

Martin

Message 8 of 10
wfberry
in reply to: wilsonm2000

I was hoping that someone may have this in a lisp or something.  But here is what I would do.  By exporting these points after they have been adjusted to the existing ground elevation, it seems that you could put these points, etc in individual columns in Excel, then have the "numbers" in the descriptions subtract from the newly acquired ground elevation giving you elevation points for your new surface.

 

Then save these points (Pt number, X, Y, Elev) in a new ASCII file and re-import.  Either delete all your old points or have the new one overwrite them.

 

Bill

 

Message 9 of 10
neilyj666
in reply to: wfberry

The correct (?) way to tackle this problem is as follows (I do this regularly for this very application)

 

  1. Ensure that your peat spot levels are positive and cover the whole of the OGL or area of interest - turn on triangles and add lines extra points etc etc. If the levels are negative then the technique below will add the levels to a surface which is a techniquie I use to add spoil mounds to a surface.
  2. Then create a volume surface with the peat depths as Base and OGL as comparison surface (see screenshot).
  3. Do a few checks using the tootips and you'll find be able to verify that the surface has built correctly.
  4. Create a new surface and paste the Volume surface into it - this turns it into a regular surface that can be added to profiles, corridor targets etc etc.
  5. It also remains dynamic so if additional site investigation points are added to the peat depths surface the base of peat level surface will update as well.
  6. This ensures that the base of peat mirrors the undulations of the ground which in most instances is fine but if there are many ditches then the base of peat will be a distance below the ditch.
  7. This technique can be used for most glacial type deposits but probably wouldn't be so good below rockhead (although could be useful with caveats).

neilyj (No connection with Autodesk other than using the products in the real world)
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Message 10 of 10
wilsonm2000
in reply to: neilyj666

Brilliant, thank you so much Neily 🙂  yet again, you have helped me lots.....

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