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.

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  • 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”.
  • Thanks for the replies Caddcop, you are one of the few that understand my blight. Your workarounds sound rather ingenious, but also signigicantly outside the realm of something we could implement. I guess its back to flipping faces for 4+ hours just to add 10 points to our surface.
  • Unknown said:

     I've even tried adding breaklines to force the triangles to form and retain edits, but found that other triangles can be effected by the added breaklines and will often change in a manner that requires even more breaklines to be needed.

    Caddcop, just out of curiosity...have you experienced the same issues using the soft breaklines?  Honestly, I haven't seen the behavior your speaking of myself...not that it's not happening, I don't doubt it, but just wondering if the newer feature type may alleviate the problem.  The only issue I've seen with the soft breakline feature type is that it's not a supported feature in the older DTM format, so an export will keep the triangulation as shown in the terrain model until you re-triangulate the DTM, then they "disappear".

    I too like the idea of an audit trail of modifications to the terrain model to prevent the issues Roadrunner is experiencing.  It's one thing to disjoin the surface from the survey data, make changes to it, then re-join it because you're trying to add survey data to it...I could sort of expect the behavior that's being experienced (that's a whole different discussion), but another workflow that shouldn't have any issues (at least in my mind):

    • Turn off (from Survey Settings) Create Terrain Model for All Field Books
    • After importing survey data, you need to manually right-click field book to Create Terrain Model...
    • Make edits as necessary
    • Bring in add-on survey into new field book and create its own terrain model.
    • Use the Create Complex Terrain Model command to join the surface data as required.

    The problem that I'm noticing (which I'm sure you have experienced as well) is that once you try to do an Append, the flipped triangles go back to the way they were.    This just shouldn't happen.  Like you mentioned...some sort of audit trail would be able to prevent this from happening.

    If you do a Merge instead, this isn't the case...the triangles stay flipped, but there are other unwanted results I'm sure depending on the dataset.  Without the audit trail however, I'm sure some other command would flip them back at some point even if the merge was an acceptable method for the dataset.

  • What exactly is a "soft" breakline?

    Due to a number of issues, my terrain editing has primarily been in Ss2 and earlier. We can't get all of what we need out of Open Roads Survey and our clients are still in Ss2, so I have avoided much in depth Open Roads Survey work.

    I assumed the reformulation of triangle has to do with the triangulation algorithm. When a new breakline is added, the algorithm looks for its "smallest possible triangle between three points" and finds a different group of points now that certain previously eliminated triangle are now acceptable due to how the added breaklines cause them to form.


    Charles (Chuck) Rheault
    CADD Manager

    MDOT State Highway Administration

    • MicroStation user since IGDS, InRoads user since TDP.
    • AutoCAD, Land Desktop and Civil 3D, off and on since 1996
  • Inside the Help section, they reference three types of break lines:

    • Break Line - Breaks are used to designate linear features such as edges of pavement, ditch bottoms, ridges, etcetera where an abrupt change of slope occurs. Any longitudinal element may be defined as a break line. Triangles will not cross a break line in the terrain model.
    • Soft Break Line - A soft break line is a break line, however, if it crosses a break line, it will not affect the triangulation and is ignored.
    • Graphic Break Line - A break line is a soft break line that is not stored in the terrain model.

    We obviously understand the Break Line element.  The two new ones however are either not defined all that well or difficult to understand how implemented.  Actually though, it may seem like the Edit Terrain Model - Swap Line command may be utilizing the Graphic Break Line feature type.  It happens, but it's not really stored.

    As for the Soft Break Line, it should be defined as - A soft break line is a break line, however, if it crosses a break line, it will create vertices at the point of crossing and re-project the element to those new vertices.

    For example, with a line added as a soft break line crossing a break line:

    I drew a line from a spot elevation to a point on the edge of a driveway crossing the other edge of the driveway.  Yellow elevations show elevation of the line where it intersects with the triangles...green are those elevations of the actual surface at the same points.

    After adding the soft break line, three vertices are added and the triangulation changes as such:

    You will notice that the elevation doesn't match what existing was (green) or where I drew the yellow line in space, but where it extrapolated between the endpoints and the breakline interception (purple):

    Sorry ahead of time for color discrepancies...gotta love JPG conversion/uploads to the site.  You should get the idea though.

    As for soft break lines added not in contact with an already existing break line:

    After adding it as a soft break line:

     

    As you can see, the line reacts as a normal break line.  The triangulation goes to where I actually placed the line.

  • So a Soft Breakline is sort of a Draped Breakline that only reacts to elevations when it crosses a breakline. If it crosses a triangle leg that is not a breakline, it will create a new triangle leg that follows its location and elevations?

    Charles (Chuck) Rheault
    CADD Manager

    MDOT State Highway Administration

    • MicroStation user since IGDS, InRoads user since TDP.
    • AutoCAD, Land Desktop and Civil 3D, off and on since 1996
Reply Children
  • Yeah, you can sort of think of it that way.  Keep in mind, if you drop a line in where the vertices are not already part of the surface, it will triangulate to those from the break line:

    Before (yellow line about 15' above base ground):

    After adding it to the surface as a soft break line:

    I highlighted the actual break line generated.

  • 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.