Thursday, February 28, 2013

Printing PDF Topo Maps (and Map Packs)

CalTopo has supported PDF printing for a little while, but it was tucked away until I made sure that generating the PDFs wouldn't overload my server.  It's now front and center in the UI, along with higher resolution PDFs and an important new feature - multi-page map packs.

First off, clicking the print icon in the top right will no longer bounce you straight into browser print mode.  Instead it brings up a menu for choosing between browser printing and the PDF generator:

The new print menu
The PDF option was initially tucked away as a link on the browser print screen, built out to satisfy some grumbling users who wanted exact 1:24k prints.  Since then I've found myself using it almost exclusively - the prints are higher resolution and you aren't limited to a fixed set of zoom levels.  It seemed time for a promotion to first-tier status.

Now for the good part - when you choose "Create a PDF", you can mark up to 15 pages on the map and dump them into a single PDF file for printing.  Here I've marked several pages on a user's Big SEKI Loop map, all with a 1 inch : 1 mile scale:

When I click "Generate PDF" they come back in a single file, along with an overview page that shows how the maps are positioned relative to each other:

The first page of the PDF shows individual map placement
So try it out!  You can also check out a sample 1:24k PDF of the popular Bunny Flat routes up Shasta, with slope shading.

Please note that this may become a paid feature at some point, depending on how much extra work it creates for my server and the degree to which I need to make a living off CalTopo.


  1. I've been looking around the web at USGS mapping software and this printing feature really makes caltopo *extremely* helpful. No where else that I've found has the ability to set the map scale, which is a pretty important feature. Keep up the great work!


  2. Nice job, feature worked for me. Question on Datum? I created a .pdf in 7.5 US Topo. Should I select NAD 27? Wondering, 7.5 maps created that way first, so is that the datum I should set on the GPS for that trip?

    1. For small scale topos, it doesn't matter what the source layer was in, just that your GPS is set to whatever you choose when printing the page. Some of the USGS scans included UTM grids, and it can get visually distracting to have blue UTM lines from CalTopo on top of the original black UTM lines if they're on different datums, but that's not the case for most quads.

      Changing datums simply causes the grid lines to shift several hundred feet. It doesn't change how the basemap is printed, so there's no "right" answer, as long as you're consistent.

  3. I'm jazzed that you gave a link to the Big SEKI Loop. I hope other people enjoy it. Question about Page Sizes -- any reason you don't make 8.5x14 and 11x17 available as standard choices? Those would be convenient options.
    Thanks for the terrific tool, and thanks for serving up maps for Gaia GPS too. Amy

    1. No good reason. Some very basic user testing suggested confusion around custom page sizes for browser printing in CalTopo, so I decided to start by limiting PDFs to predefined sizes. Due to concerns about server load I started degrading the PDFs beyond 8.5x11 anyway, so I didn't pay much attention to the large sizes.

      I added the page sizes you asked for and, since things have been going smoothly, eliminated most of the degredation at large sizes.

      Two things to note. First, while all PDFs will now be at 200dpi, the server will only fetch 120 tiles per page, so 11x17 and larger maps may be slightly fuzzier than 8.5x11/14 ones. Second, generating a large number of big pages requires a lot of memory and a lot of tile fetches, so it will take a while for the server to actually produce a map pack

      I'm due to upgrade the server. At that point maybe I can up the tile limit for larger pages as well.

  4. Matt - here's a question/comment that's not related to this thread.
    I use an iPhone while on the trail to create email journal entries each night. When I have WIFI access, the queued emails get sent to where they are then posted to my blog. I create the email using the PCTHYOH iPhone app, and that embeds a link showing my location on a google map.
    The problem is that google maps are terrible for showing backcountry locations. I want a link that opens CalTopo with my location flagged.

    Is there an iPhone app already that creates an i-am-here link to a CalTopo map? Is it possible? All it would need to do is create a link and copy it to a clipboard, so user could paste it into an email - nothing else needed. Or, more elaborately, create an email message and put the link into the message. Essentially, do what PCTHYOH does but with a CalTopo URL instead of a Google URL.

    Well, this is probably out of your range of interests, but I thought I'd ask.


    1. Off the top of my head, no. You can pull the lat/lng out of the PCTHYOH maps link and use that to show a map centered on your position by substituting it into the /map.html#ll=... URL, but that's probably more intervention than you're looking for. There's also currently no way to place a marker on the map using the URL, so you'd get a map centered on your location but no icon to say "I am (or was) here".

      That said it's something I'll keep in mind. There are some free / open source apps that have asked about using my map layers but can't afford to pay the data charges their users rack up. I've been pondering ways to have their apps integrate with parts of CalTopo as an alternative.

  5. Matt, first off thank you so much for Caltopo! I accidently stumbled across your site while looking for online\offline mapping app\program to use for creating routes and then printing them. I would like to make one suggestion. The ability to add text onto a map would be ideal for adding a description or trail names to printed maps. Especially when printing maps at 1:18000 or higher where the trail names do not appear on the map. I would be willing to pay for this added feature as a premium account. Thanks again for all the hard work!

    1. Thanks Jorge. The ability to add free-form blocks of text to the map is already on my to-do list, although I'm not sure when I'll be able to get it done.