Modelling a river bank in autocad

[mark0]

Hello,

So, I started a project in autocad for my disertation in which I want to recreate a medieval fortress. It is my first time using Autocad as a 3d tool(not that I have used any before) and i am stuck at creating a river bank for my project.

The thing is i need the bank to be at an angle, i tried using the fillet command but it is not working as expected (at least as expected by me). Using autocad is esential for this project since i really need to keep the GPS coords in place and, also, it is the only software i have that is capable of this. 

Is there any way i can draw an irregular shape as a polyline (a river, in this case), extrude it, substract it from a bigger surface(the "ground") and then smooth the edges to a specific angle?

Thanks.

 

[ReMark]

One option: Create a series of horizontal profiles for the river and then loft them.

[mark0]

And can I somehow split the original polyline/extruded object to separate objects or horizontal profiles? 

I need some kind of an angle to be somehow natural, at least from a far render to look kind of ok.

The real problem is that I need to recreate the ditch system they has an angle of 65-80 degrees.

[ReMark]

A single profile is the equivalent of cutting a ditch  perpendicular to its centerline and looking at it head on.  You can create a profile with any angle you want. 

[mark0]

I dont really know what you are telling me about. As I said before, it is kind of my first time using AutoCAD for serious purposes. 

Could you pinpoint me to a tutorial that explains extensively what you are trying to say? 

Also, I have found this: 

 which is somewhat relevant(or at least I think). I haven't got to try it yet. 

Also, sweep function gave me some ideas.

 

Edited February 23, 2019 by mark0

[ReMark]

Here is an example of a simple approach.  Create the profile of your riverbank (use a single continuous polyline) and extrude it all a spline representing the center of the river.  Look at the image below.  On the left side we have a spline (white) and a simple riverbank profile (tan).  We extrude the profile along the "path" of the spline to achieve the result on the right which in this case ends up being a surface.  

 

[BIGAL]

This is a day to day task for CIV3D or any other road design software. Remark has given you a very good answer. I would extend the banks above the existing surface which must be a solid make it a closed shape rather than flat edges then subtract from the surface this should give you a ditch.

 

Suggestion 1 There are some free civil design software out there just google it is found here at Cadtutor.

 

Suggestion 2 Ask here nicely its a few minute job to do this if you supply a dwg with 3d faces. A water surface can be added pretty easy also as a seperate surace for rendering.

[mark0]

I did manage to create my river with information provided by you guys and i thought it would be a simple task to create my defense ditch the same way...well, it isn't. My ditch (as well as my river, but I just went and ignored that for the sake of simplicity) is wider in some areas than in others and i couldn't really manage to join the parts together. 

What i did is:

1. Create a solid object in the shape of the river / defense ditch to simply cut the whole thing.

2. Create the surface(bottom of the river) and simply place it over the subtracted area that was created earlier (i rendered the thing and it looks OKish)

What i couldn't do: join the wider parts with the thinner parts (i did small segments one at a time) to create the impression of continuity. 

 

Sadly I am not at home and I don't have access over the original file so i just created a new one as fast as I could based on a 17th century map. 

What i've based my 3d so far on:

https://imgur.com/a/Huut6H3

+ archaological plans that we collected on the field (mainly drawings of the real width of the ditch and its profile).

 

The main question of my current post is: Can i join (or overlap in a way that wouldn't affect the render) two surfaces of different dimensions(width mainly) or even edit one by stretching it to the point i need it to be? I searched on the web for some solution but I did not find one.

 

In the DWG the `ditch` is the red spline

@BIGAL can you, by chance, give me a tutorial on doing this in civil 3d? I will talk tomorrow with my thesis advisor to give me a civil 3d license 

 

rec.dwg

Edited March 6, 2019 by mark0

[CyberAngel]

If you're wedded to the idea of using AutoCAD, study the LOFT command more carefully. You can change the dimensions of the ditch/riverbank along the path to get the variability I believe you're looking for. Not only that, LOFT gives you a mesh that you can edit vertex by vertex if necessary.

 

Civil 3D probably has more horsepower than you need, but if you intend to work in that field, you'll need the experience.

[mark0]

I got the Civil 3D license but, as you said, I lack experience. 

I lack experience on AutoCAD 3d too, but I am far more familiar with  its interface (although they seem similar). 

[BIGAL]

The bottom line is you must have a surface that covers the entire project you can add 3dfaces into the surface to make it bigger or as suggested strech the egdes. We often add a dummy point or 2 to make a surface work the Z value used is experience.

 

For me the changing of the moat batters ie width, using CIv3D you could make 3 alignments and join them, the tops would follow the existing surface, the bottom would be at say one level. This will make a changing "V" shape. Same with the river. 

 

[SLW210]

On ‎3‎/‎8‎/‎2019 at 2:18 PM, mark0 said:

I got the Civil 3D license but, as you said, I lack experience. 

I lack experience on AutoCAD 3d too, but I am far more familiar with  its interface (although they seem similar). 

 

Since you now have Civil 3D, you might try asking specific questions in the Civil 3D & LDD Forum on how to accomplish this task.