Creating a Surface from Points

[hrigsby]

Good day:

So I have a grid survey of points and I've entered these points into Civil 3D.  Now what I want to do is use these points to create a surface so that I can create a slope analysis of the surveyed area.  My problem is that I can't get the points into a point group.  

I have a generic grid (15 x 15) of points set up and I've only used a portion of them (defined by the dimensions of the site).  So I want to create a surface that includes all of the points that aren't set at an elevation of 0.  

I'll attach the file so ya'll can see what I'm working with.  

Thanks in advance for the help.

[MikeEvansUK]

You have AutoCad Points in the file only cogo points are useable in a point group.

Three methods:

1. use Dataextraction to create an xyz file of the information then create a surface and attach to definition as point file.

2. Same as above but import as cogo points or just convert to cogo points

3. Just add to the surface under definition > Drawing objects > points.

[hrigsby]

Awesome.  So now I have my points into a surface, and I'm trying to run the analysis on it.  The percentages and areas show up fine in the table, but I can't seem to get the colors to show up on the surface.

Any idea what I'm doing wrong here?  I used the "Drawing Objects" method to add the points to the surface if that makes a difference.

Thanks again, I'll attach the updated file.  

[troma]

Did you set the surface to ignore data at 0 elevation?
Do you have "Slopes" turned on in the surface style?
Did you do a slope analysis in the surface properties?

[hrigsby]

I isolated the points that had an elevation when I created the surface.  The surface style is set to "1M and 5M (Design)" I have a "Slope Banding (2D)" option but not a "Slopes" Option.  

And yes I ran an analysis and added a legend.  The legend has data in it and looks fairly accurate but the colors aren't showing up on the actual surface.  Is this a surface style problem?

[MikeEvansUK]

Edit the surface style, on the display tab, turn on the little lightbulb next to the slopes section.

You need to read up on styles they are the only way to "play music" with this app.

[hrigsby]

Now we're getting somewhere!  Thanks everyone!

One last thing.  Is there a way to make the surface "triangles" smaller?  My grid is on a 3m x 3m array, but I'm only getting 2 triangles per square (divided from top left to bottom right).  Is there a way to keep this but also get a division from bottom left to top right so that each square of my grid has 4 triangles within it?

I was assuming Breaklines were my method here, but I can't snap to the points in my surface so the breakline is sitting at an elevation of 0 and creating holes in my surface basically.  

[AllenJessup]

You can Smooth the Surface [AeccSmoothSurface].

This will add points to the Surface and create smoother contours. But it doesn't increase the accuracy at all. Only adding more data will do that.

Allen Jessup

[AllenJessup]

What are you using to create the breaklines. 3D Polylines or Featurelines. You should be able to snap to the endpoints of the triangles or have the Featureline take the elevation form the surface. However I don't think this will do what you're looking for. Are you looking for smoother contours or a dencified surface?

You can also insert point manually at the centerpoints of your girds. But, again, the only source of an elevation for those points is the existing surface.

Allen

[hrigsby]

I guess densify the surface would be a better term for it.  I want to double the number of triangles that are present on the surface, essentially connecting all of the points that I used to make it to it's adjacent points.  I'll attach a screen capture that shows what I want it to do (in the red, uneven lines).

[AllenJessup]

You can draw those lines as featurelines and Assign Elevation. Chose your existing Surface. If you've already drawn them. You can select From Surface in the Elevation editor.

Allen

[troma]

If you add a data point in the middle of your square it will triangulate from there to all the corners. But what elevation do you give that point? Are you just going to interpolate from the surface? Then it isn't going to change a thing; you're adding surface data back into the surface.
Unless you add data, the surface will either triangulate one diagonal or the other across your squares. That's why it's called triangulation: it makes triangles.  And it only uses the existing data to do it.

[hrigsby]

I created those lines and added them to the surface as breaklines and it works to an extent.  It breaks my triangles in the opposite direction than I intended, but it does divide them in half.  So I'm getting closer I guess. 

[neilyj666]

perhaps you should increase the density of the survey grid?

[AllenJessup]

You could Swap the faces on the triangles if it's important enough to take the time.

Allen

[neilyj666]

...if you have just surveyed a 15 x 15 grid then you will results as shown. The survey needs to be done to pick up the actual ground conditions where the changes in slope occur and a regular grid can be output from this if desired.