Hi,
is there any recommendation how to check data for overlapping polygons?
The data are structured in such way there are several levels with polygons only (when not, it's an issue but can be detected easily) where the overlap is not allowed, both in the same level (which is not supported by overlap analysis I guess) and also between levels. In fact it leads to check "every polygon feature with any other from the same or another level".
Is it possible? It looks to me it belongs to basic data quality checks, but I was not able to find how to do it easily in BM.
With regards,
Jan
Hello Jan,
I could refer you to the Design File Cleanup. One of the cleanup action is called Overlaps. The help file said : "The Overlap tab contains controls used to identify two elements that partially overlap one another." I think is what you looking for. For more details about it, I will refer you to the online help from MicroStation:
https://docs.bentley.com/LiveContent/web/MicroStation%20Help-v14/en/DesignFileCleanupDialogBox.html
I hope that helps.Sebastien
Hi Sebastien,
did you try it?
I thought about this tool also, despite of it's a bit "too simple CAD" and not topology check, but first of all it seems it does not work at all. I tried to configure overlaps check with the attached design file, where a few overlaps exist, and I have not been able to receive any output.
Bentley Map CE Update 2 on Windows 10 used.
polygon-overlaps-check.dgn
Bentley Accredited Developer: iTwin Platform - AssociateLabyrinth Technology | dev.notes() | cad.point
I agreed this is a CAD tool. It is his inherit from MicroStation. I can make it work without any problem, but for a user looking for topological analysis, the results may be unsatisfactory. I also think about Bentley Map topology tools (which will be ported to in the next Map Connect Update 3). But those are lineworks analysis tools and none verifying the polygon overlapping. The closest could be the Find Slivers tool, but it won’t flags all polygon overlapping cases. Only sliver cases ones.
I'm sorry I couldn't be more helpful.
Regards,Sebastien
Sebastien Lefrancois said:I can make it work without any problem
It's weird, but I am not. I tried polygon-overlaps-check.dgn, attached in my previous answer, with MicroStation V8i and CEU11 and BM CE U2 and I was not able to use Data Cleanup utility to select overlapped polygons (shapes) ... but they exist evidently.
What I am doing wrong?
Sebastien Lefrancois said:I'm sorry I couldn't be more helpful.
That's fine, thanks for your effort. I guess the final solution will an addin (as so many times in BM because of lack of tools) to achieve exactly what the customer needs.
Hi Jan,
From your file, I can flag shape overlapping by setting tolerance to 4 (see screen capture). As I said above, and since this is a CAD tool, I understand the results is not effective in geospatial context. Sorry for inconvenient.
Thank you again for your comment. This is very appreciated. I will share your feedback with the team.
Regards,
Sebastien
Sebastien Lefrancois said:I understand the results is not effective in geospatial context.
It would be still better than nothing, but my problem is that I do not understand how this tool work :-(
Originally I thought that Tolerance means how big overlap (in area master units) is treated as is / is not overlapped. In other words, 0 means "no tolerance" and "find all overlaps, even the smallest". But because 0 finds nothing and 4 finds something, it seems to be another value.
Sebastien Lefrancois said:Sorry for inconvenient.
In the case of this particular customer and project, the simple CAD approach would work on part of input data, where no other context is required for analysis. But because it's not clear what Tolerance means and the results are messy in my opinion, own code is the only solution.
I will discuss this issue in MicroStation forum, because I'd like to know whether it's bug in the tool, not clear formulation in documentation or I just do not understand the documentation.