maps

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A wide selection of maps that you can extend yourself is one of the core features of the Trailmap app. Why would anyone need many maps, when plenty of sports and outdoor apps get by with a single one? The reason is simple: nobody has invented that one perfect map, and probably nobody ever will.

By using different maps and combinations of them you can make route planning and moving in the terrain easier - but it does take a bit of groundwork to get familiar with the world of maps. This article goes through the different maps and their combinations, and uses examples to show which situations they suit. These days you get most of the useful combinations straight from Trailmap's Map settings menu with a few taps, without having to build maps yourself. At the end of the article there are also instructions on how to create, copy and edit your own raster maps - a skill you need if you want to bring in special data that the app does not already include.

The different map types

A map's job is to present, in simplified form, location-bound information about the surrounding "reality": high-level information such as where the waterways, buildings and roads are, mid-level information such as where the trails, hills and marshes are, and detailed information such as how a road is surfaced, what its speed limit is, how rough a trail is, how many people travel along a trail, and so on.

The map maker always has to make choices about what information the map shows, because it is impossible to present everything at once in a readable form. This challenge has led first of all to a top-level division of maps into base maps and overlays:

• Base maps ("base"): the job of a base map is to give an overview, covering at least the "high-level information" described above. A very simple base map like the National Land Survey's (NLS) Background map is typically meant to be used together with one or more overlays. A base map can also be considerably more comprehensive, including even detailed information - in which case the challenge becomes the sheer amount of information on the map and therefore its readability. An example of a map with a mid-level information richness is the NLS topographic map, and of a very rich one, Trailmap's own vector map.
• Overlays ("overlay"): overlays are typically specialised in presenting one particular kind of information. Good examples are the different map layers of the national Digiroad: road surfacing, speed limits, traffic volumes, functional class and so on. An overlay is not usually used on its own but is drawn on top of some base map.

The second choice for the map maker is deciding how the information is visualised. The most common approach is to use various abstract map symbols to represent different types of information. Map symbols typically differ a little between maps, so it is worth getting to know the map legend in order to understand how the map you are using depicts things (in Trailmap you open the legend from the "Map legend" option in Map settings, or from the map's info button). Instead of map symbols you can also use images - orthophoto maps, for instance, which are made from processed aerial and satellite imagery. It is also possible to use a very pared-down graphical approach: hillshading, for example, depicts landforms by shading slopes and hollows according to a defined sun direction, and Strava's heatmap uses colour and line thickness to show how much Strava users have travelled the different paths (roads and trails).

A third division of maps comes from the map data itself, i.e. what information the map maker has available and how accurate it is. Map data is covered by copyright law, and the data sits with different organisations that are not willing to share it freely with each other - often combining it is also restricted quite tightly. Trailmap makes particular use of the following data sources:

• National data from the National Land Survey and other organisations (Digiroad): these contain the most comprehensive and up-to-date description at a general level and of the built environment. Correspondingly, their biggest weakness is poor coverage of forest trails and partly also of forest roads and tractor paths, and there is no information at all about the condition of forest trails ("technicality", i.e. rocks, roots, unevenness).
• OpenStreetMap (OSM) is a global community map, founded in the UK in 2004, originally collected mostly by volunteer contributors ("mappers"); these days there are also numerous mapping teams from large companies (Meta, Apple, Amazon and Microsoft, for example). The map is therefore based on crowdsourcing and is a staggering example of what is possible when there are simply enough mappers. OSM's decisive advantage is that anyone can add to the map data relatively freely with any information at all. The flip side is the challenge of keeping quality even.
• LIPAS is a national database of sports and recreation sites maintained by the University of Jyväskylä. From it Trailmap uses, among other things, official outdoor and hiking routes as well as outdoor sites (lean-tos, campfire sites, viewpoints and similar "POI" points).
• "Other map data": this is a large category of specialised data sources that can be attached to Trailmap - they are not a fixed, built-in part of it. One example is the heatmaps from Strava (a US-born social sports app), which offer a very interesting view into where people in different sports actually move.

Trailmap's own maps (the Trailmap and NLS vector maps, more on those below) are in fact already combinations of several of the data sources listed above: the same map contains, for example, OSM trails, NLS landforms and LIPAS outdoor sites. This is a big difference compared with the older approach, where each map was typically a "raster image" of a single data source and you had to stack the different sources yourself.

The OSM trail map

In mountain biking, the age-old challenge has been "where are the trails and what are they like to ride, i.e. how technical are they". To solve this, Antti Nissinen kicked off OSM-based trail mapping in Tampere in 2013. The need arose because the trail coverage of the NLS topographic map is very poor in many places, and it says essentially nothing about how rideable trails are: on a topographic map, a smooth pine-needle trail and a rooty, rocky rock-garden trail are drawn with one and the same map symbol. Antti's idea was to have mountain bikers map the local trails into OSM: so that at the very least they record accurately where the trail runs, how wide it is, how rideable it is, and whether the surface might be soft or muddy, or whether it gets overgrown in summer.

The mapping started in the Tampere area but over the years spread across the whole of Finland. The Trailmap app in turn grew out of that trail mapping: the aim was both to support the mappers' work and to make the resulting map data easy and widely usable. That is why OSM map data is at the heart of Trailmap: Trailmap's own maps are based mainly on it, and the route planning function relies entirely on OSM. Trailmap also includes special features to support mappers, making it easier to extend and maintain OSM.

The result is exceptional even by international standards: Finland has over 31,000 km of trails described in OSM and classified by technicality (the mtb:scale tag). That makes Finland one of the best-covered countries in all of Europe for mountain bike trails - in practice only Italy is narrowly ahead. This is entirely the work of volunteer mappers and an absolutely remarkable achievement. It is precisely this data that makes Trailmap's trails so comprehensive, and it is why Trailmap's own vector map shows clearly more and more accurate trail information in many places than traditional topographic maps do.

Map reliability and accuracy

One of the most important things with maps is to understand that no map is - or can be - a perfect description of reality. Many app users assume a map is a kind of flawless "truth" about the terrain, but unfortunately that is not the case with any map. A map is always someone's simplification, collected from some data source at a particular moment and with particular methods - and there is always room in it for gaps, out-of-date information and outright errors.

Errors come from many sources. The terrain changes constantly: trails appear and grow over, roads are built and closed, bridges disappear in storms. Data sources update at different rates, so the same feature can appear differently on different maps. A map also always generalises: a small trail may run slightly differently on the map than it does in the terrain, and a map symbol only roughly describes what is actually out there. With OSM the particular characteristic is that the data is crowdsourced - the great majority of the information is very good, but quality varies by area depending on how active the mappers there have been, and any individual feature may also carry old or incorrect information.

So the practical rule of thumb is: use maps as a tool and as support for planning, but do not trust any single map blindly. When you move in terrain you do not know, it is worth comparing several maps and data sources against each other, using common sense, and being prepared for the route not going quite the way the map promised. The same goes for heatmaps and other "hint" data - they tell you where others have been, not whether a route is passable right now. Trailmap's route planning warnings and surface information help here, but the final judgement out in the terrain is always down to the person making the trip.

Trailmap's vector maps

Trailmap's default map is Trailmap's own vector map. It is built especially for moving on trails and minor roads, and combines several data sources into a single map: OSM's comprehensive road and trail network, NLS's accurate landforms (contour lines and hillshading) and LIPAS outdoor sites. Previously a comparable view had to be assembled from several separate raster maps (the old "3D MTB" map, among others); these days all of this comes ready in one vector map, which is also sharp at every zoom level and whose appearance can be fine-tuned in many ways.

Trailmap's vector map: a comprehensive trail network, trails coloured by technicality, and landforms all in the same map

The big advantage of the vector map is that OSM trails are classified by "technicality" using colour. Technicality tells you how difficult trails are to ride on a mountain bike, and at the same time how hard they are for a trail runner to run or a walker to walk. The map also makes wet spots, path surfaces and landforms easy to pick out. Add NLS hillshading on top of that, and elevation differences come across straight from the map even for people who are not used to reading contour lines on their own.

Trailmap also offers an NLS style ("MMLv2") of the vector map, which looks more like a traditional Finnish topographic map but still uses OSM trails and other vector data. That way you get a visually more traditional map without losing OSM's trail coverage. Below, the Trailmap style on the left and the more traditional NLS-style view of the same terrain on the right.

The Trailmap vector map (https://storage.googleapis.com/trailmapv2.appspot.com/left?GoogleAccessId=firebase-adminsdk-e34s5%40trailmapv2.iam.gserviceaccount.com&Expires=16447010400&Signature=EjcjPjnYKk6DyiHXCQ4O%2F3vyJlvjOCg0cOjJs%2Bf9cXU0DBo1riczqweRJunZqVs5mhjvCAuvn32qe%2FYtwJWRfnRodpDi%2F9Y60DCOosYcpvfcm8oflPx4aRZ2uKNramJiccDCziJDiW1%2BYoi7bbHzCQdUj%2BX61kpHRjtqiSxrAI6tGJ%2FWpFLVYcP5cErThKnO0c2jdC89R%2BxH0GxEkjUtWNtuAig7zdmKmV8Em%2BpiPyRzEaqjSA9PCgNRwATbgPQtIrsBFhd3ZWNhMBHJ5%2By7KVWIKD8n1RSaMZFgE0VX2P3hS5kt4Jf2C7%2F7OMTRGJj01TCoxFXsH4yH3g8xxXvcTQ%3D%3D) and the NLS-style map (right) of the same terrain

If you want a completely traditional raster topographic map (the NLS topographic map as such, for instance) or some other raster map, that works too by choosing "Other" as the map style - more on this in the Map settings and My maps sections.

Choosing the base map: Default, Aerial and Background

You can pick three different bases for the vector map, found under the "Base" option in Map settings:

• Default: the normal, information-rich vector map with all its detail. This is the best general-purpose map for most situations.
• Aerial: an aerial image (an orthophoto, i.e. satellite imagery) as the base, with OSM roads and trails drawn on top. This matches the previously popular "orthophoto + trails" combination, but now you get it with a single tap. An aerial image lets you see the terrain "as it really looks" and reveals details that are not normally marked on maps, and the paths drawn on top tell you where you can get through.
• Background: a pared-down, light base map. It works well when you want a calm backdrop for viewing a route line or overlays, for example.

The Aerial base: OSM roads and trails drawn over an orthophoto help you make sense of the terrain

Sport-specific variants

There are a few variants of Trailmap's vector map that emphasise different things depending on what you are doing. The handiest way is to use the profiles at the top of Map settings (MTB, Gravel, Walking, Winter), which pick a suitable variant combination for the sport in one go:

• MTB: emphasises trails and their technicality - the best choice for mountain biking and exploring trails.
• Gravel: emphasises roads and their surface (gravel vs. asphalt), so the network of gravel and minor roads stands out clearly. Excellent for gravel, touring and road cycling route planning.
• Walking: a more pared-down view geared towards outdoor recreation and hiking. The map's main data comes from the NLS topographic map, supplemented with OSM trail information.
• Winter: shows ski tracks and maintained winter routes; suits skiing and other winter activities.

The Gravel variant emphasises roads and their surface, so gravel roads stand out clearly

Profiles are also "memory slots": when you change map settings while a profile is selected, the settings are saved to that profile. That way you get your own ready-made settings for different sports or situations, with quick switching between them. You can build the "Custom" profile exactly the way you like, and the "Restore profile defaults" button takes you back to the starting point.

Overlays and special maps

When you want a completely different or specialised view, use overlays on top of the base map you have chosen. You bring up an overlay from the "Overlays" option in Map settings, and using several overlays at once works too. By adjusting transparency you can bring the base map or other layers through from underneath the overlay.

Good examples of overlays are the Digiroad map layers, such as "Paved road" and "Speed limit". They give a quick overview of the public road network: which roads are gravel, which are asphalt, and at what speed limits. You can seek these out or avoid them when planning a route - and the roads that are not in Digiroad are usually smaller and quieter (though their condition can vary).

A Digiroad overlay on the base map: the larger roads suited to planning a gravel route stand out

Heatmaps are another useful special map. A heatmap is built from the routes of people out and about (the GPS tracks of sports watches, bike computers and phones) so that the map shows the paths with lots of traffic as "hot" and the ones travelled more rarely as fainter. If a path has no colour at all, it does not mean nobody ever goes there, but at least it is not popular with the active people who record their outings. Trailmap has no heatmap of its own (the data is not public), but you can bring up Strava's heatmaps as an overlay by adding them "as your own map" - see the guide. Note that heatmaps do not usually distinguish between seasons, so they include both summer and winter paths (a winter path might run across a marsh), which means heatmap traces are also worth using with judgement.

The Strava HD heatmap on top of the map: you can see at once which paths are the most popular

Tip: many workable combinations used to have to be built by hand, by copying and tweaking maps (just the trails on top of an orthophoto, for instance). With the current vector map you get a large share of these straight from Map settings: choose the "Aerial" base with trails, switch to the gravel variant to see road surfaces, or turn on a Digiroad or Strava overlay. You mainly need your own maps when you want to bring in data the app does not already have.

Map settings

The "map" button in the top left of the map view opens the Map settings menu, where you control everything shown on the map. (This menu replaces the map lists behind the older version's "stack" button.)

The Map settings menu

At the top of the menu are the profiles (MTB, Gravel, Walking, Winter, Other, Custom), which switch to map settings suited to the sport in one go. Below them you will find settings including the following:

• Base: choice of base map - Default, Aerial (orthophoto) or Background (pared-down). In raster map mode (the "Other" style) this selects the actual raster base map.
• Overlays: one or more map layers on top of the base map. A few overlays come with the app; you get more with the "My maps" feature (described below).
• Property boundaries: shows property boundaries on the map (Finland).
• Depth contours: water depth information on the map (Finland, a Plus feature).
• Map legend: opens the legend for the selected map layers. Note that legend images are often large and may require scrolling.
• Routes: shows the official routes from OpenStreetMap and the LIPAS database on the map.
• Places (POI): shows OSM and LIPAS database place categories (lean-tos, campfire sites, viewpoints and so on).
• Photos: shows photos published by users from trails and roads on the map.
• High contrast: an easier-to-read version of the map, suited to bright sunshine and a small screen.
• Colour tone: boosts the brightness and contrast of the Trailmap map (Default / PLUS / SUPER).
• Map elements: choose in more detail which details are shown on the map and how.
• Shortcut buttons: adds quick buttons at the edge of the map that let you make certain choices faster (the same choices are always available in this menu too).

The "Restore profile defaults" button at the bottom returns the selected profile's settings to their starting point.

You can also set the map style to the NLS vector map or to the "Other" option, which switches on the traditional raster maps. With the Trailmap style you additionally have various variants available (sport-specific emphases and the "winter" variant for ski tracks and maintained trails, among others).

Map view buttons and keyboard shortcuts

The map plays the lead role in Trailmap's interface: the opening view is a full-screen map view. The most important map buttons:

• Top left: the "map" button (Map settings) and a shortcut to the traditional topographic map. Below these is the momentary hiding of tracks (the tracks are not deleted, just hidden), which lets you see what is on the map underneath a track.
• Top right: zoom and full-screen view, place search, the map legend (info button), locating your own position, and the 3D terrain map button, which tilts the map into a three-dimensional terrain model (a Plus feature).
• Country selection: when several countries are visible on the map, the app offers country selection buttons (Finland, Sweden, Global, for example) that switch the maps and features in use.
• Context menu: right-clicking (or long-pressing the map on a touch device) gives you a menu at the cursor where you can see OSM map details, the coordinates of the spot, Google Street View, or add a place of your own.

When you have many layers on in the map view, handy keyboard shortcuts are available on a computer:

• Space briefly hides route lines and dims the main map layer - helpful for viewing overlays (Digiroad's "Paved road", for example).
• "1" briefly hides all tracks, and "2" hides other tracks except your own route - so you can quickly glance at what is underneath them.
• Esc ("Escape") briefly dims the overlays - handy with strong overlays (Digiroad or the Strava heatmap, for instance) that otherwise cover the base map.
• "3" is the same as Esc, but successive presses hide and restore the overlays alternately.
• "S" opens and closes the Google Street View at the cursor.

My maps

Trailmap comes with a good selection of maps and overlays ready to go, but you can also bring your own raster maps into the app - some special data source or a foreign topographic map, for example. These are managed through the "Maps" menu in the navigation bar ("My raster maps", among others). Your own maps can be used as base maps with the "Other" style, or as overlays with any style.

The "Maps" feature opens a list of both the app's ready-made maps and your own. The "..." button to the right of each map lets you copy or edit the map, or (for your own maps) delete it. You add a new map with the "+ Add map" button at the bottom of the list. The easiest way to get started is to copy an existing map and edit it, which shows you what information a map layer is built from.

Trailmap supports a few different types of map source:

• XYZ: the traditional "Google Maps" / "Web Slippy Map" type of map source.
• WMS: a standard widely supported by the National Land Survey and Digiroad, among others.
• WMTS: in practice a variant that can often be used in XYZ form.

The map URL requires the use of variables that identify the map tile to be fetched: {z} is the zoom level, {x} the x coordinate and {y} the y coordinate. You can also use the {s} variable, which is replaced by the letter a, b or c (rudimentary load balancing that some servers still use). In other apps these variables may be in a different form, so be careful if you copy a URL from elsewhere: sometimes {z} is {zoom} and {s} is {switch:a,b,c}. No other URL templates may be included.

Examples of map sources:

1. OpenStreetMap (XYZ): https://tile.openstreetmap.org/{z}/{x}/{y}.png
2. Digiroad (WMS): URL https://avoinapi.vaylapilvi.fi/vaylatiedot/digiroad/ows, "Layer name" dr_liikennemaara, "Layer style" dr_liikennemaara
3. NLS topographic map (WMTS, but choose XYZ as the type): https://avoin-karttakuva.maanmittauslaitos.fi/avoin/wmts/1.0.0/maastokartta/default/WGS84_Pseudo-Mercator/{z}/{y}/{x}.png?api-key=(your own API key from the NLS OmaTili page)

The other values on the form are needed more rarely, and usually when they are, the information can be found in the tile server's documentation. Two useful ones are "Max zoom" (how far the map may be zoomed; the default of 20 is usually fine) and "Max native zoom" (the most detailed zoom level the tile server actually produces, typically 12-18; the app scales more detailed levels programmatically).

The Trailmap app's "My maps"

The name "tile server" comes from the fact that map layers are produced from small pieces of image ("map tiles"), either 256x256 or 512x512 pixels, which are loaded into the map view as the user moves the map around. The seamless map you see on the screen is therefore made up of these pieces joining up with each other. Defining your own maps takes a bit of familiarity with how tile servers work - help is available from the Trailmap community if you run into difficulties here.

Maps for Garmin

In addition to the Trailmap app, certain map layers can also be downloaded to some Garmin sports watches and bike computers. More about those in this article.