I used Didger to digitized a bunch of contours with polylines but they should be closed polygons. How can I fix this? You can easily convert a polyline to a polygon by following these instructions: Select the polyline or polylines. Click Draw | Change Boundary Type | Polyline to Polygon. The polyline(s) are converted to polygons. Updated January 13, 2017 Have more questions? Submit a request 0 Comments Please sign in to leave a comment.