Adding an image overlay to help draw boundaries

Danielle's Avatar


16 Jul, 2019 02:26 PM

I often find myself needing to reference backcountry zones when planning my backpacking routes, mainly for permitting purposes. But these aren't available in any of the Caltop layers I've found. I thought maybe I could take a screenshot of the available maps online, upload them as a custom layer, and then trace the zones with polygons. Is this possible? I haven't been able to figure out how to add a JPG as a custom layer.

  1. Support Staff 1 Posted by rmarcucci on 16 Jul, 2019 08:31 PM

    rmarcucci's Avatar


    Its possible. The image needs to be available elsewhere online.

    Adding layer
    Add geospatial image
    Find web address for it: jpg, gif, png ex: (
    The interface to line up the image with the map is a bit clunky, but here's how it works. Pick 2 points on the image that are easy to find on the basemap as well, ideally somewhat diagonally located from each other

    Rightclick georeference: mark point 1 on the image
    Rightclick georeference: mark point 2 on the image
    Turn opacity of the image to 0
    Rightclick georeference: mark latlong1 match the point on the basemap
    Rightclick georeference: mark latlong2 match the point on the basemap

    Thank you for using Caltopo,

  2. rmarcucci closed this discussion on 16 Jul, 2019 08:31 PM.

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