Skip to main content
  • EN
Hi,

 

 

I have different lines which are crossing and intersecting. I can detect where they are crossing and where they are intersecting by using a SpatialFilter.

 

 

But where they are crossing I need to know which one is the upper one. Compare it like 2 roads that are crossing: 1 on ground surface and the other one is a bridge -> I need to know which one is the bridge and which one isn't. I don't have specific information related to the z lvl of the lines.

 

 

Thanks a lot
Hi,

 

 

am I correct in understanding that all your objects are 2D only, and that there are no other attributes to indicate bridge or not? All all features are in the same dataset?

 

 

David
Yes, the lines are 2D, no extra attributes are present execpt an unique id per line. All features are in the same dataset

 

 

Hi,

 

 

If you were to to this intersection manually, using pen and paper to explain, how would you proceed to determine which of the lines represent a bridge or not?

 

 

Once this is clear, it will become much easier to translate your process to FME.

 

 

David

I have drawn 2 different lines (for display I used 2 different colors).

 

Road A is the bridge as the red line is fully visible while road B has a short interuption

 

But isn't that simply a function of the drawing order, and therefore mostly a function of the order of features in your dataset?

 

 

I do not see how FME could be able to tell which is on top, unless the order of features in your dataset is the deciding factor.

 

 

David
But in the original source it is intentionally drawn like that. Or does this order changes everytime the data is loaded?
What is the original source and how was it drawn (what was the criteria for the drawing order)? I do not know.

 

 

Maybe your answer lies there.

 

 

David
Drawing order is first all the lines at ground surface and after that the bridges.
And how can the software that draws these lines make that distinction?

 

 

David
Hi,

 

 

If a line can cross only one other line, this could be a prototype.

 

 

Takashi

 

 

Takashi, I fully agree with your prototype, as long as one can trust that the first feature delivered by the reader is always a bridge. However, such a dataset would leave me surprised and slightly worried :-)

 

 

David
Thanks Takashi, I can work further with this 🙂

Reply


Community Stats

30,108
Posts
114,295
Replies
37,744
Members
Terms & ConditionsCookie settings
A product of
Safe Software respectfully acknowledges that we live, learn and work on the traditional and unceded territories of the Kwantlen, Katzie, and Semiahmoo First Nations.