Best Practices for adding survey data to an existing surface?

This has been discussed before but without any efficient answer I am asking it again in a slightly different manner.   We survey large irregular property for a local municipality that requires MicroStation.  These sites always require additional topo work to be added after the initial surface is created.  A typical request would involve updating the topo to include areas that have changed due to construction or simply expanding the original topo area.

Each time we add data to the existing surface we must RECREATE THE ENTIRE DTM AND RE-EDIT EVERY SINGLE TRIANGLE THAT WAS EDITED DURING THE ORIGINAL SURFACE CREATION. This process can take days to accomplish depending on the size of the site.  Some sites are over 5 miles long.  

What we need is the ability to add data to a surface without having to re-create it, similar to the the way Civil3d functions.  A 30 minute surface addition in Civil3d can take days in Microstation.  This is extremely frustrating and adds thousands of dollars and tons of wasted time to these projects.  Just yesterday an area was uncovered and it was surveyed.  The area consisted of less then 15 points which needed to be added to the existing surfafce.  Simple, right? Hell no, we had to recreate the DTM and re-edit the triangles.  It took 8 hours to complete what should of taken 15 minutes.

Please do not tell me to 'fix the survey data' or to make every triangle a breakline.. This has nothing to do with bad survey data.  I have been creating surfaces for 25+years and each and every surface needs a detailed review and editing of triangles, basically just flipping faces so the surface is correct.

  • It would help if we knew what version of what product you were using to assist. Sorry, I must've missed the earlier discussions of this topic.
    I don't think Kevin's answer is what you're looking for since you mentioned flipping triangles which would fall within an exterior boundary which could be re-triangulated to what it originally was.

    How are you currently flipping the faces now?
  • Power InRoads V8i Select Series 4.
    I flip the triangles using “power inroads”, “surface”, “edit Surface”, “change triangle edge”.
  • This issue STILL EXISTS in OpenRoads Designer contrary to what the friendly Bentley rep told me over the phone.   This is utter nonsense on an epic level. Days of time wasted editing the same triangles over and over and over again.  I would love for someone to correct me and show us how Bentley allows triangle edits to actually HOLD.  

  • When you flip a triangle edge, you are manually identifying where a breakline should be.  The field crew failed to collect the breakline because they either weren't paying attention or, much more likely, it was too subtle for them to recognize.  You should add the breakline to force more accurate triangle creation.  If that causes nearby triangles to change undesirably, there were two (or more) breaklines missed and will need to be added in the office.

  • Ray, that is 100% inaccurate. If the crew misses data, it produces bad data and flipping triangles will not fix it.  Triangle flipping is 100% necessary to produce an accurate surface unless you have a scanned surface with points on 1' spacing.

    Just because the software places triangle in a certain location does not mean that is where they should be to accurately reflect the ground surface. The software is smart but its not that smart.  Other software handles editing once, this one doesn't 

  • I beg to differ.

    The way the algorithm works, the TIN is created by triangulating the surface as if all the points are random.  It then compares triangle edges to breaklines and adjusts the triangles so that the triangle edges do not cross the breaklines.  Once the TIN is created, every edge identifies a change in the surface slope.  The edges are implicit breaklines.  The only way to force an area to triangulate a specific way is to explicitly define a breakline.  That's what you do when you flip triangle edges, whether in InRoads, OpenRoads or Civil3D.  Civil3D's advantage is that it automatically logs that edit and applies it when the surface is re-processed.  The analog in InRoads or OpenRoads is to create an explicit breakline in the model or a graphic element that can be imported each time the TIN is processed.

    Missing data is simply missing data.  If we look only at the points and lines that define the geometry of the surface, data is missing only if that lack of data results in an inaccurate model.  The task of the field crew is to collect all data needed to create an accurate model.  If the TIN doesn't accurately reflect the ground, something was missed.  In a case where flipping triangle edges resolves the problem, the survey crew didn't miss a shot, they simply missed making the connection between two shots.  If the survey crew had made the connection, you would not have to flip the triangle edges; additional shots would not be needed.

    Please don't take this as an assault on survey crews.  I've been on field crews and I've processed survey data.  These are errors made on every (and I mean that literally) survey.  A process is needed to reveal those errors so that they can be addressed.  Part of the process for most surveys is scrutinizing the TIN and flipping triangles.

  • The other added influence is the density of shots taken. If the density of shots is not uniform then the triangulation will potentially be inappropriately formed (requiring a face to be flipped). But it's not needed if the density is appropriate for the surface being collected.

    Civilly yours,
    The Zen Dude (also known as "Mark")
    Civil Software Guru & Philosopher
    InRoads User since its birth in the 80's
    OpenRoads Documentation / Training / Support
    Zen Engineering, Owner
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