3D for rendering

I use Autocad 2006 and keyterra-firma for ground modelling and design.

I have created an overall landform on a large site and now wish to add site roads and paved areas. As these are complex shapes at differing elevations I am struggling to create a solid for rendering which I can design over my landform model. Is there a simple way to draw a road (for example) for rendering? I also want to render my ground model grid 'underneath' and around the areas that I have designed.

I work in AutoCAD 2000i.

My suggestion would be to draw the path you require using something like a polyline, then draw a rectangle at one end of this and extrude along the path drawn.

Sorry if this is not explained well but hope you sort this out somehow.

Good luck!

Thanks craigp,

Unforunately the forms I am trying to render are not regular in any way and as such a rectangle will not do (unless I am misunderstanding). Imagine for example an irregular shaped paved area in the middle of a city centre with drainage falls and a road sweeping down to it which gets wider and narrower around houses. What sort of surface can be drawn in this situation?

Hope I am being clear and not too thick about this one.

Regards,

MGM

It may just be me not understanding. Have you got a picture of what you are trying to acheive so i get a better idea???

I have put a sketch together but I am not sure how to post it. I could email it to you if that is OK.

I have put a sketch together but I am not sure how to post it. I could email it to you if that is OK.

Upload the picture to the CADTutor File manager Iicon at the top right that loks like two sheets of paper)

This will host the file for you and then just use the image tag (under the subject line) when you post a reply and use the image location you just uploaded.

The image shows an aeriel view of the ground model (green grid) and some OS data around the site. I have sketched on a road coming through the site (in orange) and a 'paved' area (in pink). As you can see the road is not uniform in any way and neither is the paved area. They are both irregular shapes and are over varied heights. I want to be able to draw this road and paved area by snapping to the grid so that I can render them. As far as I can establish a 3d polyline cannot be made into an object and a 3dmesh has to be a rectangle. Maybe I am missing a trick. Hope this is a better explanation.

Many thanks

Very good explanation. I am unable to help you with the varied heights but to get the irregular shape into 3d you could draw it using polylines and polyline arcs and the extrude the shape.

Have you tried experimenting with the drape command?

Yes, I have tried that. If you give a 2d polyline a thickness and then drape it, it loses its thickness and becomes a 3d polyline. Thanks though.

Here's how I'd do it.

1. Save this code below into a lisp file and load it

(defun c:terrain(/ loop_quit p1w p2w p3w p1t p2t p3t ent_a)

(command "ucs" "w")

(setq loop_quit 0)

(setq depth (getreal "What depth do you want the path to be? ")) (terpri)

(while (= loop_quit 0)

(setq p1w (getpoint "Click on the first point ")) (terpri)

(setq p2w (getpoint "Click on the next point ")) (terpri)

(setq p3w (getpoint "Click on the last point ")) (terpri)

(command "ucs" "3p" p1w p2w p3w)

(setq p1t (trans p1w 0 1))

(setq p2t (trans p2w 0 1))

(setq p3t (trans p3w 0 1))

(command "pline" p1t p2t p3t "c")

(setq ent_a (entlast))

(command "extrude" ent_a "" (- 0 depth) "-5")

(command "ucs" "w")

)

)

2. Draw a closed 2d polyline over the path, move it down below

the terrain and then extrude up suffiently so that it completely

encompases the terrain. You now have a VERY thick path.

3. Use the lisp routine above to create a series of 3d triangles on

the terrain around the area of the path. Remember to click the

points either clockwise or anticlockwise for the whole path, or

some of the triangles will extrude in the wrong direction.

4. When you've finished creating all the triangles, union them

together and you should have a 3d surface in the region of the

VERY thick path.

5. Do an interection of both the 3d terrain and the path and you

should now have you 3d path following the lie of the land.

Any problems, post me back - good luck

Spacepig

Thanks Spacepig,

(Been away for a few days)

I will try that and let you know how I get on.

Thanks again.

What is the main function of Drape command, i'd taken a whole course of AutoCAD 2006 but never told about this?