topic Re: Selected features within a buffer not getting accurate results in ArcGIS JavaScript Maps SDK Questions

Selected features within a buffer not getting accurate results

JssrRR — Tue, 02 Jun 2015 17:42:39 GMT

I am working on a Javascript application where I have a MSD published on ArcGIS server and I am using the URL from it's REST services. I am trying to select census block points that fall within a defined buffer distance and get a summary of number of blocks and housing units. I have it working but I am not getting consistent or accurate results, especially as the number of selected features increase.

I have the buffer circle set like this:

circleBuffer = new Circle({ center: mapPoint, geodesic: true, radius: radius, radiusUnit: "esriMiles" });.

When I check the number of blocks selected within a 10 mile buffer around the same block point in ArcMap, I get different results. I tried with changing this, mode: FeatureLayer.MODE_AUTO, to ONDEMAND and SELECTION but still no difference in results.

I have attached the JS file for the application if anyone can take a look at that and suggest what needs to be changed to correct this.

Thanks

Re: Selected features within a buffer not getting accurate results

thejuskambi — Tue, 02 Jun 2015 18:22:24 GMT

Quick question, why are you passing circleBuffer.getExtent, and then looping through the response to find if it is within the circle. pass the circle directly and get the result.

I am not sure how the client contains logic is implemented. nor if the point size is considered to identify if it is within or not.

Re: Selected features within a buffer not getting accurate results

JssrRR — Tue, 02 Jun 2015 18:44:14 GMT

Hi Thejus,

I am using this sample from the API reference and that is how it is done here:

Select with Feature Layer | ArcGIS API for JavaScript

If you can show me how to do that as per your suggestion I can try and see if that works.

Thanks

Re: Selected features within a buffer not getting accurate results

RobertScheitlin__GISP — Tue, 02 Jun 2015 18:58:03 GMT

The reasoning behind the esri sample using the circle extent is that the query operation on an extent is much faster and less data is sent to the server. The client side operation of determining if a geomerty is in a polygon or not is very efficient.