<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body dir="auto"><div dir="auto">Hi Matt.</div><div dir="auto"><br></div><div dir="auto">The trick is to use the attributes to id each layer before you run the intersection. So create a new field for each layer and give each polygon the same number. So layer 1, maybe 1. Do the same for the second or even third layer, use 2, or something different from the first layer. Complete your intersect and you can determine the origin of each resulting polygon.</div><div dir="auto"><br></div><div dir="auto">If you use 1 and 2 to identify the layers. New polygons with the attribute of 1 or 2 did not intersect. Polygons with 1 and 2 did.</div><div dir="auto"><br></div><div dir="auto">Kirk Schmidt</div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div id="composer_signature" dir="auto"><div style="font-size:12px;color:#575757" dir="auto">Sent from my Galaxy</div></div><div dir="auto"><br></div><div><br></div><div align="left" dir="auto" style="font-size:100%;color:#000000"><div>-------- Original message --------</div><div>From: Matthew Carroll via QGIS-User <qgis-user@lists.osgeo.org> </div><div>Date: 2023-11-11 3:45 a.m. (GMT-04:00) </div><div>To: qgis-user@lists.osgeo.org </div><div>Subject: [Qgis-user] intersection question </div><div><br></div></div><div dir="ltr">Hi there,<div><br></div><div>I'm fairly new to qgis, and hoping someone can point me in the right direction for a problem I'm trying to solve.</div><div><br></div><div>I need to intersect two polygon layers, and identify which polygons from the original layer are, essentially, the ones that were "split" by the intersection process.</div><div><br></div><div>In this example I'd want to identify polygons 1,2,4,5 since 3,6 are the same as in the original layer.</div><div><br></div><div><img height="183" width="542" alt="intersection_example.png" src="cid:com_samsung_android_email_attachmentprovider_1_2624_RAW_1699790904356" onmouseover="imageMousePointerUpdate(true)" onmouseout="imageMousePointerUpdate(false)" name="com_samsung_android_email_attachmentprovider_1_2624_RAW_1699790904356"><br></div><div><br></div><div>Ideally those polygons would be identified somehow in the attribute table for the intersection layer.</div><div><br></div><div>In addition, is there any way to build some tolerance into the process to account for spots where the polygon boundaries on layer 2 don't align 100% perfectly with layer one.</div><div><br></div><div>Thanks so much for the help,</div><div>Matthew</div><div><br></div></div>
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