Snapping New Features to Other Shapefiles
This may be useful if you are using a GPS and software which generates a point Shapefile from waypoints downloaded from the GPS, or using the CSV to Shapefile plug in. Users can then ???snap??? features (such as a line or polygon) to these points to create the new shape.
The concept of snapping features to other layers means that when generating a vertex for a shape close to the relevant point, MapWindow will force the new vertex to have the exact coordinates as the feature on the first layer. This avoids errors where the vertices may be slightly offset when created manually.
The general process for generating a line or polygon Shapefile features snapped to points from another layer is:
- Load your points layer into MapWindow. It may be useful to label this layer with the Identification field if the order of points is important.
- Ensure GIS Tools and Shapefile Editor are both switched on in Plug Ins, and zoom into the relevant section of the points layer
- Click on [Shapefile Editor] and ensure there is a tick next to [Snap to vertices] and [Snap to All Layers]- if you have multiple layers loaded.
- Create or load the line or polygon layer the new features are to added to. Ensure that this layer is the next in line above the point layer.
To create a shape, follow the instructions as per Editing a Layer section;
- Move the cursor close to the first point, you may see the + move over the point ??? click once to create the vertex
- Move the cursor to the next point for the site, and repeat until you have created a vertex on the last point.
- To close the polygon, or finish the line, right click, which will finish the shape.
- Repeat for each new shape as required.
- Add attribute data to each shape as required.