surface methodology

[rmk]

i have 3 contiguous lots approx. 125' x 250'. each lot has a home, driveway, sidewalks and pool areas.
there is about a 12' drop in elevation from the street level to the rear of the lots abutting a stream.
the lots are a mixture of lawn and wooded areas, so a regular grid was not possible. we have a good many random shots
with several swales located.

what would be the best approach to build a surface that includes all three lots. there is a lawsuit involved and we need to
have a finished contour map of the property.

should i build the surface with all points, then create feature lines and sue them as breaklines or should i create the breaklines first and add the data after that.
and somehow i'm guessing i need to take out the area where the houses and pools are.

any suggestions and/or ideas would be greatly appreciated as i have not done a project like this one before.

[ccowgill]

our linework comes in with our points, but in the event you need to add them manually, reduce the points, make that your starting point, then add the breaklines, as they will modify the triangles. add hide boundaries (non destructive) for the houses/pools

[Tom Beauford]

Like ccowgill our linework comes in with our points. I would want to go to court with a drawing where the linework was drawn by a the field crew who were at the site not in a cubical the next day by someone who wasn't there. Whether there's issues with field data or not I have the field crew review the drawing for errors before showing it to anyone else. Curved feature lines from field data for your stream and swales carry elevation creating accurate surfaces you cannot produce otherwise.

[remi678731]

It depends on how the field crew has there data collector set up and the methodology used whether the linework is generated in the field. I always have the field crew review the contour data. If the data is very critical as this sounds I would do a site visit with a contoured map tape and camera and review the map on site.

[Iceberg]

I never use all of the points when creating a surface. I create a separate point group that I add only survey points that are ground shots, this could be a pavement shot, ground shot, etc. For example GR (Ground) and PA (Pavement) are the codes my survey crew use, I add those points only to my point group.

I then create my feature lines using the remainder of the points that I need to create a surface, Curb, Sidewalk, Building Outline, Walls, etc. I add the feature lines to the surface as my break lines (fault lines) and this is how I get the extra data into my surface.

I will then look over my surface and add additional points, if necessary to my point group by selecting those points using the "Include Tab". Maybe their are some shots along a fence that would help model the surface better, select those points.

Use a hide boundary for areas that you don't want included in the surface, inside the pool and house for example.

I try to keep the surface as simple as possible. I have seen some issues when adding the same points to my surface that I also use as feature lines, such as points that define a curb, let the feature lines define these points instead of the actual points.

Make sure you define any swales or streams with break lines, between 5 to 6 break lines, top of bank, bottom of bank and centerline if they shot those points.

The CAD manager has not set up auto line work so I have to manually create a surface and these are the steps I typically use.

I also like to split my screen into 2 views, one is 2d drafting and the other is a shaded 3d view that I control with 3dorbit. This way I can see the surface model and make adjustments as needed.