How to find certain grade (1.25:1) at existing topography

[artbiscocho]

Hi all, I have 200 acres housing project and areal topo.. My client want me to show on my constraint map all the location of  natural grade having a slope of 1.25:1 or greater and determine the area. Is there a way using civil 3d to do it. I could do it on the conventional way of using my scale and topography plan, but it is time consuming.

Thank you!!!

[doni49]

With just an aerial?  No.

But if you have surface data which you can use in C3D, then yes it can be done.

[rkmcswain]

...I have 200 acres housing project and areal topo..

Depends on what you mean by "aerial topo". If it's vector data such as a shape file or polylines, etc. then you can turn that into a C3D surface and do your analysis.

[doni49]

---

@rkmcswain wrote:

...I have 200 acres housing project and areal topo..

Depends on what you mean by "aerial topo". If it's vector data such as a shape file or polylines, etc. then you can turn that into a C3D surface and do your analysis.

---

RK is correct.  In my little corner of the world, when we say aerial we mean aerial photo.  But you did specifically say aerial topo, so that could very well mean 3d vector data.

[artbiscocho]

Thank you for immediate reply, yes I have surface data for the areal topography (contour and elevation). Can you help me how to do it.

Thank you!

[doni49 · Accepted solution]

Here's a really simplified example just to show you what it'll look like.  I created a surface that is just a collection of a rectangle at elevation 0.0 and a bunch of random points at random elevations.  Then I turned on "Slope Banding".  Everything in green will be 1.25 or greater.

[doni49]

Here's the dwg file used in my example. 

[artbiscocho]

It works like magic!!! I salute you buddy..

[doni49]

Glad to help.