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.
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
Inside the Help section, they reference three types of break lines:
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.
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.
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.
No offense but the algorithm is complete garbage then. I don't need a TIN explanation, I've been doing this 30 years and have never ever had the TIN issues I've had with this software.The field crew has no control over how a program will determine how it will connect the dots (besides creating breaklines and even then it can't control how the adjacent points connect to them) Having them add random breaklines to simple ground shots in the field is just wrong.
I can QA/QC a surface in Civil3d very quickly and efficiently and it only needs to happen ONCE. Its not the field crews fault MS doesn't support having a real person QA/QC a surface. The one we see all the time is when you have 3 shots in a row and the tin pulls a long thin line from the 1st to the 3rd point. I know the TIN isn't supposed to do this but it does. Answer: Flip face.
In reference to the Zen Dude, We encounter irregularly shaped surfaces all the time both in survey and when designing complex finish grade surfaces and in these instances face flipping is a must. Even CadCop had an issue with this in his engineering design surfaces. It can be impossible to obtain accurately spaced shots in areas of dense brush and tress and such, or if the crew has restricted access. I prefer my surfaces to be under my control not just press the button and walk away. Thank you for the replies.
The answer seems to be 'don't complete any surface edits in the office. Just press the button and whatever happens, happens. Any edits that are made will need to be done multiple times over and over and over as more data is added to the surface'. Very poor structure indeed. If weren't forced to use this program due to the monopoly they have on highway departments we most definitely wouldn't. Its the most backwards setup ever.