What does Overlay Events (Location Referencing)

Question

Hi,

can someone please explain what Overlay Events (Location Referencing) does in non-Star-Trek-Wording? https://pro.arcgis.com/de/pro-app/latest/tool-reference/location-referencing/overlay-events.htm. An Example would also help.

I was told by Esri Consultants that i can use Overlay Events to Query from one Event Attribute to an Attribute in another Event. When i tried it i noticed, that if i have several Features in one Event hat have matching RouteID, FromMeasure, ToMeasure, FromDate and ToDate only one of the Features is included in the Result.

I tried to make an Support Call (Esri Case #02938437) but the Answer was "We dont know what this function does so your result is not wrong"

NathanEasley · Answer

Hi Mirko,

What you're describing above is how dynamic segmentation works and is not a bug.

Think of dynamic segmentation as a process where you overlay multiple event layers on top of each other, then split them into the largest segments that have the same attributes.  As you described above, if you have event records from different event layers, but they have the same From Measure, To Measure, From Date, and To Date, then they would output a single record in a dynamic segmentation because they overlap spatially and none of the attributes change throughout the length of the segment.

Nathan
ArcGIS Roads and Highways team

MirkoMosch_AIDB · Answer

Hi Samuel and Nathan,

thank you for your reply. I read the document Nathan provided and already the first Sentence "Dynamic segmentation is the process of transforming linearly referenced data (also known as events) that have been stored in a table into features that can be displayed and analyzed on a map." made me shure the problem i described above is indeed an Error.

In my Case we are handling Highway Data, that describes the Surface and Segmentation of the Road and its surrounding. So we have several Lanes, Shoulder, Trenches, Grass Area, etc.. As Measure Values typicaly goes from intersection to intersection there are many Features that have matching FromMeasure and ToMeasure Values. As it is our initial Data all FromDate are set to 01.01.2021 an the ToDate is Null as all Data is currently valid. But all Features have different offset, Width, Surface Type, etc.

Can someone please confirm or deny if that Behavior is an Error or not:

* When several Features have identical RoadID, FromMeasure, ToMeasure, FromDate and ToDate only one of that Features is in the Result.

NathanEasley · Answer

Hi Mirko,

If you want to understand dynamic segmentation a bit better, you can take a look at this document that a colleague at Esri produced a few years ago https://www.esri.com/news/arcuser/1002/files/dynseg_2.pdf.  You can disregard second half of the document where it highlights tools in ArcMap 8.2, but the introduction of the document explains (with diagrams) dynamic segmentation pretty well.

Nathan
ArcGIS Roads and Highways team