Friday, February 19, 2016

Custom Layers

For advanced users, CalTopo offers a number of custom layers: MapBuilder, viewsheds, sunlight, scanned maps, DEM-based shading and third-party WMS and tile sources.  A persistent issue with these layers is that they are tied to either the map you are working on, or the URL of a blank page.  It's easy to go wild customizing them, and then suddenly find yourself starting from scratch with a new map.

In a long overdue solution, you can now save custom layers to your account.  Every custom layer dialog has a "Save To Account" link at the bottom which adds that layer to your account:

As with maps, these layers are listed on a tab on the account dialog:

And shown in a separate section of either the layer dropdown or the overlay list, depending on how the layer is configured:

Additionally, for subscribers, these layers will show up in your KML SuperOverlay File, or for pro users, WMS or WMTS Service:

A viewshed overlay in Earth
Sunlight analysis viewed in Earth


  1. Very cool. I often found myself defining the same DEM shading when creating new maps.

  2. Is there any way to be able to move a historic overlay map independently of the map it is overlaying? I often view historic maps but often, it doesn't line up with current landmarks like roads and such.

  3. I'm just discovering Caltopo and had a question about creating or importing georeferenced custom layers from PDFs or JPGs. 1) Is it possible in Caltopo to create a new layer (a custom image overlay) from a PDF or JPG (a state park map, for example) and georeference it from within Caltopo? From searching your blog, I see that this was possible in the past but I'm not clear if it's still possible. 2) If I create a custom image overlay in Google Earth, and export it as a KML or KMZ file (does it matter which one?), can I import that new overlay into Caltopo and view it as a layer over the basemap?
    My main purpose is to overlay georeferenced state park maps over a basemap and create tracks by tracing the state park map trails, for trails that are not typically visible on other topographic maps, and then see how the new track appears on other topographic map layers.

    1. 1) You can create a custom layer from a JPG that's hosted online somewhere, but not from a PDF. The UI is a bit clunky but it's under Add New Layer -> Add Geospatial Image.

      2) CalTopo's KML import feature only recognizes lines, points and polygons. You can't create the overlay in Earth and then import it into CalTopo.

      Have you looked at the OpenStreetMap / MapBuilder layers? OSM generally has good trail coverage for local and state parks, and might eliminate the need to trace over the park map.

    2. Wow, you're right, I hadn't looked at the MapBuilder layers, and even most of the minor trails are included. Thanks. I guess for any local map with more obscure trails that I'd like to "trace," I could always scan the map and host the jpg online myself and create a custom layer in Caltopo that way, or I could always just create the custom layer in Google Earth, trace the map there, then save the track as a kml and import the track into Caltopo and have fun exploring the path with all the topo maps.
      Thanks very much!

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  5. I've been playing around with the custom layers and have a question for those of you with more experience. As I create a new layer, and before I save it to my account, a hyperlink appears to the right in the 'Terrain Modeling' section. From here you can delete or edit the layer and I noticed that if you click on the name of the layer, the resolution of the layer on the map (richness of the colors) increases. If you click multiple times, it will keep getting richer and richer. However, once I've saved the layer to my account I can't find a way to increase the resolution and it appears I'm stuck with the default and somewhat faded colors. Does anyone know if there's a way keep the richer colors when a layer is saved to the account?