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.
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.
I never said that the Flip Face functionality wasn't necessary sometimes, I was just stating that its use could be mitigated with stronger collection practices. I've been using InRoads, processing field data and building DTMs for 30 years and it's only until recently did we have the flip face functionality. So InRoads users have had to become desensitized to adding breaks where needed to reform triangles. It's clear that you are significantly stronger in CIvil 3D, and it's your software of choice, but understand that most of us here are InRoads users (or GEOPAK) and have come to terms with it's positives and negatives. A negative is that we've had to add supplemental breaklines so that we could lock down those triangles, but we accept that, move on, and focus on the stronger aspects of the software.
Thanks Zen dude. I understand. Unfortunately we only get to use the weakest part of the software, the Survey side. I hear its really great on the engineering side of things.