Hi All,
I’m wondering if there is a way to expand a surface without TOPO shots, we had a guy in the field do an “OG TOPO” and he missed quite a large area, I am now trying to compare this area with his post strip topo and am not getting the m3 i should be, I’m fairly new to TBC i have drawn a boundary but have no shots for approximately 4600m2 of this boundary.
What I have done in this situation is create a line under my existing topography layer out to the extent of the surface boundary. I use a best guess elevation for this line. It is not perfect, but it allows me to create an existing surface that extends to the areas I need.
Hey Greg,
A surface can be constructed of many different object types (e.g. survey points, point cloud data, linestring breaklines, 3d faces, other surfaces). If you have an assumed elevation of the area missed, you could add a breakline/polygon with that elevation applied and add it as a surface member to the original surface (or) create a new combined surface that includes the “OG TOPO” surface and the assumed grade breakline. This approach would be no different than that taken to create a design surface with breaklines, but is only as accurate as your assumed grade. Sometimes I take this approach when the provided topo does not extend far enough for a proper slope tie to intercept. I will simply create a breakline (linestring) at the edge of the survey and offset it out flat the specific distance necessary for the slope tie to intercept, then add it as a surface member. It is however an assumption, so you have to take the results with some risk of inaccuracy.
As to calculating the “actual” ground elevations of the area missed, you may be pretty limited in options. Dependent on your location and availability, state/federal LiDAR data may be a slightly lower accuracy option. This does often require some conversion of data outside of TBC prior to incorporating though.
This is perfect I just drew breaklines around my boundary and elevated them based on existing contours this helped complete my surface and gave me a much more accurate cut/fill number.
I essentially did this I made a breakline around my boundary and elevated it based on contours that were provided in a grading plan thanks for the response Damon!
ONE- is the field crew not able to go back?
TWO- what is the ground shot going to be used for?
The state data to your data (elevation) could be off from a few inches to a 1’. You could if you just needed to get by use the cross sections from the owner if there is any and/or ask for the OG surface from the owner
It was to compare our OG surface to a post strip to calculate how many m3 of topsoil we stripped,
unfortunately the topsoil is stripped so the crew couldn’t get back to get their OG shots
at that point its going to be a guess if they want some area for Qty. Shoot the scraped area and add what the removal is of topsoil in the topo point elevations. going to be a guess at that point. Will be the same a extending the surface.
The issue in this case by the time I was able to go over the data shot and realized the whole area was not covered we had already begun to excavate all areas and move fill around.