topic select layer by location returns empty results in Geoprocessing Questions

select layer by location returns empty results

davidzornosa — Fri, 23 Jan 2015 20:20:23 GMT

Hi,

What i intend to do is to get all points from Table A that fall within some records of Table B.

- Table A: point geometry. Represents events that occur in certain spots

- Table B: polygon geometry. Represents geographic, non overlapping, areas

- I turn them into feature layers so they can be fed to "select layer by location".

- "Table A layer" is the input feature

- "Table B layer" contains the selecting features

I've checked visually that there indeed exist points in table A that fall within polygons present in Table B, however all i get, when i publish the service, is an empty collection in "results".

Any ideas,

thanks

Re: select layer by location returns empty results

VandanaRaghunathan — Fri, 23 Jan 2015 21:51:18 GMT

Hello David,

Are the points and polygons in the same coordinate system when you look at their properties in ArcCatalog?

Vandana

Re: select layer by location returns empty results

davidzornosa — Fri, 23 Jan 2015 22:18:47 GMT

Hi, yes, both are in 4686. thanks

Re: select layer by location returns empty results

VandanaRaghunathan — Fri, 23 Jan 2015 22:21:18 GMT

What happens when you run this in arcmap? Do you get results from the Select by Location?

Re: select layer by location returns empty results

DanPatterson_Retired — Fri, 23 Jan 2015 22:38:42 GMT

I suspect Vandana is probably correct...It is quite possible that one of the two things are possible

1 the polygon layer isn't a polygon (highly unlikely)

2 they are in different coordinate systems

Never rely on ArcCatalog or two files in the same data frame to resolve this issue...the only way you will know is to create 2 separate data frames...add one...and only one file into each of those data frames. Mouse around on screen in both data frames and look at the coordinates in the bottom right corner of the data frame...particularly for a location that you "think" overlaps. If the coordinates differ they are not in the same coordinate system and one is either undefined, or has been defined incorrectly by using the Define Projection tool instead of the Project too. This generally happens when one file is in degrees and the other is projected...don't pay attention to the units showing in the data frame, they are meaningless unless everything is defined correctly

Re: select layer by location returns empty results

davidzornosa — Fri, 23 Jan 2015 23:31:33 GMT

Hi Dan, i did the data frames experiment. Units are ok, both in decimal degrees and visually the points' coordinates match with what should be their enclosing polygons. thanks

Re: select layer by location returns empty results

davidzornosa — Fri, 23 Jan 2015 23:40:51 GMT

Ok, first off, turning both layers (table A and table B) in arcmap correctly displays this (note the dark red dot):

Second, trying with select by location:

-selection method: select features from

-target layers: table A

- source layer: table B

- spatial selection: tried with intersect and within

result: no joy

thanks

Re: select layer by location returns empty results

DanPatterson_Retired — Fri, 23 Jan 2015 23:41:53 GMT

more options...

1 make sure that there are no current selections in the layer...it may be that one point feature got selected and doesn't fall within a polygon

2 Do it manually...if it works... good...clear the selection

3 Although visually nice, perhaps you have the parameters out of order or you have selected the wrong selection type...which should be a parameter in your model and it isn't. for example, you can select polygons that are 'within' a point...it will yield none. or if you have specified a distance which isn't in the same units as your coordinates (in this case...decimal degrees)

4... lastly...time for a screen grab...

Re: select layer by location returns empty results

DanPatterson_Retired — Fri, 23 Jan 2015 23:45:07 GMT

Addendum.... save both as shapefiles in a folder and try those

Re: select layer by location returns empty results

VandanaRaghunathan — Mon, 26 Jan 2015 16:41:01 GMT

Hello David and Dan,

Looks like the Select by Location did return results in ArcMap when run using the GP tool or Selection > Select by location? If this does not work, it probably will not work in the model as well.
Like Dan mentioned, you could export both the layers to a different format (file geodatabase feature class perhaps) and then try the Select by Location GP tool.

Vandana

Re: select layer by location returns empty results

ToddBlanchette — Mon, 26 Jan 2015 19:26:49 GMT

Hi David,

Can you provide screenshots of the parameters you set up within the 3 tools in the model? If you've checked the data (as described above) and the coordinates are indeed correct, then the only answer is that one/some of the tools are setup incorrectly (target/source/query/etc).

Thanks,

Todd

Re: select layer by location returns empty results

davidzornosa — Mon, 26 Jan 2015 20:30:13 GMT

hi vandana, nope, selection by location didn't work. If i overlap the two layers (Table A and Table B), they display the red dot in the previous post, but selection by location yields no points. thanks

Re: select layer by location returns empty results

davidzornosa — Mon, 26 Jan 2015 20:33:19 GMT

Hi Todd, because i am working with sensitive information i cannot provide more detail about the tables used. Besides that i can say that in the "select layer by location" tool i tried both with "intersect" and "within".

thanks.

Re: select layer by location returns empty results

davidzornosa — Mon, 26 Jan 2015 20:43:03 GMT

Vandana Raghunathan‌, Dan Patterson

i managed to export shapes without the sensitive info, if someone wants to take a look at them and the model's source, please send me an email and i'll send the files.

thanks

Re: select layer by location returns empty results

ToddBlanchette — Mon, 26 Jan 2015 20:51:32 GMT

I'll take a look if you like. Send away to blanchette.tpr@gmail.com

Re: select layer by location returns empty results

davidzornosa — Mon, 26 Jan 2015 21:10:49 GMT

Vandana Raghunathan‌, Dan Patterson‌

hi, interestingly if use arcmap's "select by location" on the exported shape files, it works correctly, however if i run the same option directly on the database tables, it doesn't.

I am a complete noob with gis, so maybe the cause is something very simple.

Ifyou still want to take a look at the shape files, please let me know.

Thank you.

Re: select layer by location returns empty results

DanPatterson_Retired — Mon, 26 Jan 2015 21:18:32 GMT

...that is because the select by location tool/menu options requires geometry which a table lacks ... so nothing surprising there

Re: select layer by location returns empty results

VandanaRaghunathan — Mon, 26 Jan 2015 21:20:12 GMT

In that case it could be something with the data in that particular database(I assume it is a file geodatabase or personal geodatabase). When you export it to either a new geodatabase or a shapefile, data inconsistencies get fixed. You could run Check Geometry on those database feature classes to see if there are any errors returned.

Thanks,

Vandana

Re: select layer by location returns empty results

davidzornosa — Tue, 27 Jan 2015 20:24:37 GMT

i am intrigued... shouldn't the "shape" column of the tables count as geometries?

Re: select layer by location returns empty results

davidzornosa — Tue, 27 Jan 2015 20:27:26 GMT

Hi Vandana, no its not a personal or file gdb, its oracle 11g -with SDE mounted-. If i try to use the tool you suggested, it throws an errror, besides, the following message seems to stablish that if data is in an sde database, it has to be right.

"SDE Geodatabases automatically check the validity of each geometry when they are uploaded; therefore the Check Geometry and Repair Geometry tools are not for use with SDE."

Thanks