Spatial Query on two or more polygons for line feautures double counting....

Question

Hello all,

I am developing a silverlight application that calculates the lengths of all the line features (pipes) in one or more polygons. I am using both the spatial query task and the attribute query task to accomplish the task. In order words, i first get the geometry of the polygons in the first attribute query task and then use those returned geometries in the 2nd a spatial query task. Every thing works fine except that I'm getting double counting on line features (pipes) that crosses two polygons as a result my total length of line features is more due to double counting; this is because the default is using INTERSECTS instead of CONTAINS. Is there a functionality in arcgis for silverlight API that will automatically assign an intersecting line feature to one of the polygons based on the line's midpoint? This will help eliminate the double counting.

Please help! Any helpful suggestion will be much appreciated.

Thanks in advance.

MosesAsuquo · Answer

Thank you... I will implement this and let you know. I understand the idea and the steps.

Thanks.

DominiqueBroux · Answer

My suggestion is :
  1) Do a query with Intersects relationship (i.e the default). This query will return all lines that could be counted for the polygon
  2) From the list of lines, create a list of points that will be used as reference for each line (i.e the midpoint, or the end point or whatever depending on your need).
  3) Use an intersect task to get the insersection between the polygon and this list of points. This task returns a list of graphics (the exact same number than in the initial list) but if a point doesn't intersect the polygon, the returned graphic will have a null geometry and extent.
  4) Sum the line length for each line that has a corresponding non null graphic.

MosesAsuquo · Answer

Oh ,Dominique, how about what if i wanted to use the endpoint of the line features (pipes). In order words, which ever polygon the endpoint of the line feature falls, that line should be counted as belonging to that polygon and thereby avoiding double counting. How would one implement that in code??

Thanks again in advance.