About the Maps
- What sort of maps are they?
- The American maps are scans of USGS (United States Geological Survey) topographical maps which when
printed mostly have a scale of 1:24,000. In Alaska they're a mixture of 1:24,000 and 1:63,360. In
Canada, they're scans of Natural Resources Canada 1:50,000 topographical maps. They use contour
lines to show the shape of the terrain and so are ideal for hiking and other outdoor activities.
- What areas are covered?
- The United States, including Alaska, Hawaii, Puerto Rico and the
U.S. Virgin Islands, and Canada. We believe that coverage is complete with the following
- A small triangle of land near Grand Haven, MI, is missing.
- In Arctic Canada, some maps that may never have been printed as paper editions
may not be available. The vast majority of the Arctic maps are available, however;
please get in touch if you are interested in coverage of particular areas.
- How old are they?
- The USGS maps should be the most up-to-date editions of the traditional
topos - but in many cases these can be many years old. Luckily the shape of the ground
and the courses of rivers don't change very quickly. USGS are now publishing a new
map series called "US Topo" that looks superfically similar to the traditional topos
but is based on entirely different data sources; for information about why I'm currently
not using those maps, please see this page.
The Canadian maps are the most up-to-date ones available in 2010.
If you are aware of any newer paper or digital versions of any specific maps do
please let us know so that we can fix the problem.
- But I'm looking at a map that says 1927!
- 1927 is the year in which the US Geological Survey established the standard "North American
Datum", which is a model of the shape of the earth. This is shown prominently on those maps that use
it. However, it is not the survey date. You can normally find the survey date in the bottom
right of the map. Often you'll see a series of dates as the map is incrementally updated.
- Were your maps affected by Trimble's acquisition of MyTopo?
- No. Unlike some other apps, this app has never used server resources provided by MyTopo or
- Can you make a version for another country?
- We do now have an app for Britain called UK Map using
free data from Ordnance Survey. The critical difference between these countries and the rest of
the world is that the maps are not copyrighted, or are freely licensed, so we're able to provide
these apps without paying license fees. A version for another
country would consequently be much more expensive. If you'd like to see a version for your country,
please get in touch - and don't forget to tell us how much you'd be prepared to pay for it!
- How much memory space do the maps take?
- This varies; some maps have a lot more details than others. Most are somewhere between 10 and
50 Mbytes. During installation, however, additional temporary storage is needed; the app may refuse
to install a new map if you have less than about 250 Mbytes of free space.
- Will this run on my iPod touch?
- Yes, absolutely. Of course the iPod touch doesn't have GPS; it will try to use
WiFi positioning to show your location but this is unlikely to be very effective outside of urban
areas. If you want real GPS, Topo Maps works with the Dual GPS Cradle and other external GPS devices.
Apart from that everything will work just the same.
- Does the app work when I don't have cellular coverage?
- Yes. If you don't have cellular coverage you can view the maps that you have previously
downloaded and you can use the GPS to show your position. The only thing you can't do is install
more maps. Note that you should not select "Airplane mode" as this disables the GPS.
- How can I print maps?
- You can take a screenshot - press the home and power buttons at the same time - and
print that from the Photos app. Or you can download the PDF version of the map from the USGS
online store (free of charge) and print that.
- Can I delete lots of maps without doing each one individually?
- Not exactly, but you can make the process a bit faster by first joining the maps together
in a mosaic using the blue arrow buttons, and then deleting that.
- Why is the app rated 17+?
- The help screen and waypoint download screen could be abused to get uncensored internet access, and
Apple allow this only in 17+ apps. It's unfortunate that the description of 17+ in the app store is so
vague, but only Apple can change this. There is, of course, no adult content within the app itself.
- The GPS button doesn't do anything.
- Go to the device's main settings screen and find "General - Location Services". Check that
Topo Maps is ON.
- I can move around the index map and zoom in to see the map grid, but I can't install any
- You need to touch the map square for about half a second, without moving your finger, for it
to become selected. This is necessary to distinguish selection from pan/zoom gestures.
- I've installed a map; now how do I actually see it?
- Once you can see the green map square you need to touch that for about half a second,
without moving your finger; the app will then "flip over" and show the map.
- What are the "usual gestures"?
- To zoom in, put two fingers next to each other on the screen and slide the apart, or double-tap.
To zoom out put two fingers on the screen and slide them together. To move around use one finger to
slide or "flick" the map.
- How do I un-mosaic a map?
- Flip back to the index view and select the single map that you want to view.
- How do I delete a map?
- View the map that you want to delete and touch the map settings button (it's the one
that shows a map and a gear). The window that pops up has an erase button.
- I'm finding it really hard to find the map that I need.
- You could try using the USGS
Map locator; this will let you search by placename and it uses a Google Maps base-map with
highways, towns etc. Once you've identified the map that you need (shown in black/yellow text),
search for that map name in the app.
- I get a "download error" when I try to install the map that I need.
- We are now fairly confident that, with the exceptions noted at the top of the page, all maps
are available for download. So the most likely reason for an error is a problem with the network
between you and the server. If possible, try using WiFi rather than cellular data or vice-versa.
Try again in a couple of hours. If the problem persists, please get in touch with us.
- If you're using WiFi, note that the device may turn off the WiFi connection after 30 minutes
of inactivity if it's running on battery power. Check if the WiFi symbol is still displayed on the
- Version 1.4 includes changes to the way downloads work that we hope will make the process
more reliable even if the network connection is imperfect.
- The altitude display is wrong.
- The data used for this display has relatively poor resolution, and the app interpolates
between the known points. The values shown are likely to be more accurate in flatter terrain and
can be hundreds of feet out on narrow ridges and summits. We may add more accurate data in a future
version, but this would add significantly to the size of the map downloads.
- When I flip over to the index map, it immediately flips back to the topo.
- Turn off the GPS before flipping.
- Please can you add......
- We'll be adding more features in future versions. Do please tell us what you think we should
work on next. The most common requests are for track display and recording, and for printing.
- Why do some maps need the three-minute "install" process and others not?
- During the install process the app is cutting up the map that it has downloaded into lots of
256x256-pixel tiles. This is only necessary when the downloaded file is in the original TIFF format.
For the most popular maps, we have converted them on the server to a "pre-tiled" format that doesn't
need the phone to do this work. We continuously convert more maps to this format based on the
most frequent requests to the server; currently we are able to satisfy about 95% of
requests with a pre-tiled map.
- Do I need to do anything to my firewall to make Topo Maps work?
- No, Topo Maps just uses plain HTTP on port 80.
- Where are the maps served from?
- The app first sends a request to our server which redirects it to the actual source of data
for that particular map. The most popular maps, which have been pre-tiled, come from an AWS S3
server. For the less popular maps that we don't have copies of the request is
redirected to archive.org for USGS maps or to Natural Resources Canada for their maps. The map
collection at archive.org was donated by the Libre Map Project.
- Does Topo Maps have a URL handler?
- Yes it does; it responds to URLs with the following format: topomaps:/?-102.34,47.8. (The format is quite flexible - it will try various strategies
to decipher the string - but we suggest using the format shown. A suitable printf call would be
printf("topomaps:/?%.6f,%.6f",lng,lat).) You can use this to invoke Topo Maps from another app or
from a web page.