topic Re: spatial join result in empty records in 911 GIS Questions

spatial join result in empty records

maherelayyan2 — Wed, 07 Mar 2018 05:15:44 GMT

Hi i am trying to do SJ between a buffer poly with a road layer using the Spatial Join with match options

intersect or within a distance

but it keep resulting in a one part of attributes filled and the other part from the second layer empty

although both layers intersect with each other and they are within of this distance , any suggestions ?

Re: spatial join result in empty records

DanPatterson_Retired — Wed, 07 Mar 2018 05:45:09 GMT

Are both in the same coordinate system?

(projection-on-the-fly may give the illusion that their geometry intersects, when in reality they don't)

Re: spatial join result in empty records

maherelayyan2 — Wed, 07 Mar 2018 05:54:29 GMT

Thanks i will check the projection

Re: spatial join result in empty records

maherelayyan2 — Wed, 07 Mar 2018 22:11:55 GMT

I checked both have lambert projection system

Re: spatial join result in empty records

maherelayyan2 — Wed, 07 Mar 2018 22:18:13 GMT

Re: spatial join result in empty records

DanPatterson_Retired — Wed, 07 Mar 2018 23:23:10 GMT

Maher, have you then checked that they should be matched and do indeed overlap.

BTW I hope you are using the Extents of the file in its properties to assess what the coordinate system is and not its textual description... which could have been defined incorrectly.

Re: spatial join result in empty records

maherelayyan2 — Wed, 07 Mar 2018 23:33:50 GMT

Dan see this

Re: spatial join result in empty records

DanPatterson_Retired — Thu, 08 Mar 2018 00:48:03 GMT

Maher which is why I asked about the coordinate system check...

If you make a small selection of that area, and use the Intersect tool, you should get a line where the polyline intersects the buffer. If you don't, then they are in a different coordinate system.

What I suspect is happening is that your lines are continuous for the most pare and your buffere are disjoint and overlapping. Perhaps the spatial join is assigning a buffer to a different polyline than you think.. For example what do you get for James Sea road? I can see 4 possible buffers that could have been picked during a spatial join. Which is why I think you may be getting those 'missing' values. You can try to split your buffers and/or segment your lines if you need a more fine-grained association, or try an attribute join

Re: spatial join result in empty records

maherelayyan2 — Thu, 08 Mar 2018 01:00:35 GMT

what do you mean by split your buffers and/or segment your lines if you need a more fine-grained association

Re: spatial join result in empty records

DanPatterson_Retired — Thu, 08 Mar 2018 01:16:34 GMT

You may need to add one to many in spatial join or

as they note hear, the Near table

it is possible that two or more join features are at the same distance from the target feature. When this situation occurs, one of the join features is randomly selected as the matching feature (the join feature's FID does not influence this random selection). If you want to find the 2^nd, 3^rd, or N^th closest feature, use the Generate Near Table tool.

or switch the order of the join until you get the data where you want it