3D-object along DTM

[Anonymous]

Hello community,

I have a DTM and a landscape protection area as shape file in my project. I am using Autodesk Civil 3D Version 2021. I can import the landscape protection area as a closed polyline. I now want to extrude this to a 3D object, along the DTM. So that the object has the appropriate height.

My first attempt was to project the polyline on the DTM. However, I cannot extrude the resulting 3D polyline. Or is there a solution here?

My second attempt was to extrude the closed polyline into a 3D object. Can I  cut the created 3D object on the DTM / adapt it to the DTM?

The aim is to have a 3D object "lying" on the DTM. So the lower side of the objet is according to the DTM.

I am really very grateful for your help! Many Thanks!

Best regards Annika

[neilyj666]

@Udo_Huebner nice technique - but why do you create the surface snapshot? This is not something I've done so curious to know what the advantages are and to see if it will be of use in my work. 

[AllenJessup]

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@Pointdump wrote:

I've heard the term "Solid" bandied about on the Forum, but I'd never used one before and still don't quite know what it is.

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Dave,

A solid is a basic AutoCAD entity. A representation of a 3D solid. SOLID is also an AutoCAD command. It allows you to pick points to create a solid. Related commands are BOX, CYLINDER, PYRAMID, CYLINDER, CONE, ETC.

Try this. Start the SOLID command and select 3 points, hit enter. Select the Solid and in the Properties Pallet give it a thickness approximately equal to one side. Select the solid and view it in the object viewer. You should see a 3 sided prism.

BTW: I believe that "constant thickness" would mean that the solid would be of the same thickness wherever it's measured. Not truly possible when working with a Civil 3D Surface.

[Udo_Huebner]

I need the snpashot to modify and recalculate the Surface without accessing the source XYZ files (I did not unzip them)

[Udo_Huebner]

Note: Solid is a term that has been revised several times in AutoCAD history.
1. the predecessor of Solid hatching (around 1988) is a filled 2D quadrilateral and can be called with the command SOLID. Solids are practically no longer used.
2. AutoCAD base 3D volume objects are therefore called "3D Solid", ceated with EXTRUDE, BOX, SPHERE ...

[Pointdump]

Allen,
Thank you for the short tutorial. As Linc from the Mod Squad used to say, "Solid!"
"...the [constant thickness] solid would be of the same thickness wherever it's measured. Not truly possible when working with a Civil 3D Surface."
That's what I was wondering.

Dave

[Udo_Huebner]

Not important for the initial question, but perhaps good to know:

"Solid" versus "3D Solid" - two completely different AutoCAD Objects with nearly the same name.

See this Screencast, if you clearly want to see the differences.

https://autode.sk/3r3bZhp 

a "Solid" is a very old flat 2D object - a solid filled surface with 4 points.

Yes, you can add elevation and thickness but its only 2.5D then. You can't use solids for boolean operations like (Substract or Union). This works only for 3D solids (and regions or true AutoCAD Surfaces)
a "3D Solid" is a real volume with mass and flat and curved faces

[Pointdump]

Nice! Thanks Udo!

Dave