1

I am using a new vector tile service for background mapping.

I can select/interrogate individual objects from the vector layer with the info tool - but they're not recognised by the snapping tool.

I wanted to be able to snap to the vertices from the VTS layer when creating my own layers on top.

Any ideas/suggestions very welcome!

QGIS Screenshot

4
  • Please add a screenshot showing the current settings of your snapping tool. – Erik Feb 12 at 15:17
  • Thanks Erik - added above! – Alex Feb 12 at 15:29
  • And which layer are you trying to snap to? – Erik Feb 12 at 16:40
  • Thanks again for the comment. I was looking to use snapping to create new polygons in a shapefile layer. Have found a limited workaround… not ideal, but helps a little. – Alex Feb 13 at 20:34
2

You can read the design principles of native vector tile support from https://github.com/qgis/QGIS-Enhancement-Proposals/issues/162

Vector tiles are placed on a special vector tile layer and geometries do not behave like true vectors. I guess that's why you can't snap to vector tile features.

A big problem with representation of vector tiles as vector layers is that they are not "proper" vector layers. Vector tiles are data that have been modified for efficient visualization, making compromises elsewhere:

Geometries have been split, clipped, simplified, features may have been filtered out altogether at some zoom levels. Having a polygon in one vector tile, we do not know if that is the complete representation of the feature or if the feature continues in some adjacent (or distant!) tiles. We cannot find a feature by its ID - we would need to browse through all tiles. We do not know how many features there are or cannot show attribute table of the whole sub-layer without fetching all tiles. All of these limitations of vector tiles come from the idea to make their rendering as fast as possible. We should not try to use them for other than display purposes. It is better to think of the data encoded in vector tiles as raw data for map renderer, not "true" vector data for analysis or other common GIS uses.

1
  • 1
    Thanks for the advice. That makes a lot of sense. After playing around I’ve found a workaround, but it’s pretty hacky. It’s possible to select the optimised vector objects and copy to a scratch layer - and then snap to those vertices. Not ideal, but can be helpful tracing around complex geometry. – Alex Feb 13 at 20:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.