Author

Kate Dougherty

Gaia GPS & China’s GPS Restrictions

by Kate Dougherty February 8, 2016

written by Kate Dougherty

In the interest of national security, the Chinese government strictly controls geographic data, and deliberately skews maps of the country to protect sensitive buildings and facilities. These restrictions cause offsets in the data when using GPS navigation or digital maps, but the OpenStreetMap (OSM) based maps in Gaia GPS don’t have this problem, and this makes apps like Gaia GPS popular in China.

You can find hiking, cycling, and topo maps based on OpenStreetMap in Gaia GPS. Check out these Knowledge Base links to learn how to change your visible layer to an OSM-based source in the iOS or Android versions of Gaia GPS.

Apple Maps Work, but iOS Photos and Apps Have Issues

Because Apple is an authorized mobile provider that has purchased a “shift correction algorithm,” Apple Maps will display your current location correctly on an iPhone. However, the GPS offset still causes a number of problems on iOS devices:

Your phone will offset geotagged photos. Similarly, some cameras with GPS chips may not display coordinates for users in China either.
Google Maps will only display the correct location on an Android phone, an iPhone user who recently visited China explained.
Apps that show your friends’ whereabouts will offset their locations by 300-500 meters, or about a block or two.

GPS, Mapping, and Chinese Law

OSM’s contributors build the map by collecting GPS traces and by tracing features from satellite imagery. Despite legal restrictions, a lot of this mapping has been done in China. Our recent blog post explains how to contribute to OSM, but keep in mind that due to restrictions on private mapping activities, doing so in China is illegal.

The restrictions apply to all types of geographic data; the country’s Surveying and Mapping Law effectively makes private surveying and mapping off-limits in mainland China. While the government has provisions for academic research, foreigners must obtain approval from the State Council and partner with the relevant authorities when conducting fieldwork. Individuals who break the rules can face confiscation of equipment, interrogation, and even jail time. China takes the matter very seriously, as evidenced by the nearly 40 illegal mapping cases it prosecuted from 2006-2011. Law enforcement has detained and questioned geologists and other scientists for recording what they believed to be innocuous GPS coordinates for their research.

How to Circumvent the GPS Restrictions in China

When you’re on the ground in China, using an OSM-based map is the best way to get accurate locations. In addition, if you’re a programmer working with geotagged photos or other geodata, there are several open source scripts that can help you convert WGS coordinates to GCJ-02.

Programmers can choose from scripts in C#, R, Python, PHP, Ruby, and Objective-C to georeference locations correctly. While the authors of the scripts probably used leaked code to create them, other solutions use the accurately aligned data from the Chinese version of Google Maps. Some fixes use statistical regression to interpolate GWS-84 coordinates from this version.

Did You Know? Google Maps and Displacement

You may notice the displacement when using satellite imagery in Google Maps (compared to a road map), and particularly when looking at major roads. For example, in the screen shot below, Google offsets the marked highway interchanges near the Capital Library and Beijing Vansha Outlets Shopping Center to the northeast on the street map.

Misaligned interchanges and major roads in Beijing. Credit: Google Inc.

This is because location-based service providers like Google must obtain authorization from the Chinese government to offer digital street maps of China, and buy a “shift correction” algorithm. In order to comply with the law, these companies must use the country’s proprietary, encrypted GCJ-02 coordinate system, rather than the most commonly used WGS-84 system. The satellite imagery uses the “true” coordinate system, while the street map uses the skewed Chinse system. Dan Dascalescu investigated this shift by searching maps.google.com for the known WGS coordinates of the Monument to the People’s Heroes in Shanghai (31.24427 N, 121.48695 E).

Google’s street map retrieves a location in the middle of the Wusong River, while in reality you’ll find the monument several hundred meters to the southeast, at the intersection of the Wusong and Huangpu Rivers.

Searching on known WGS latitude and longitude coordinates for a Chinese landmark retrieves an incorrect location in Google Maps. Credit: Google Inc.

Activating the satellite imagery reveals pronounced misalignment, as shown in the screenshot below. The marker appears in the correct position on the imagery.

Google.com street maps do not align with satellite imagery in China. Credit: Google Inc.

Apple Maps has the same displacement issue. Searching on the WGS coordinates will pinpoint the correct location on the imagery, but not on the map. Apple doesn’t display the street map’s road network when imagery is activated, which makes the effect less jarring. Still, the bevvy of hotels it displays in the middle of the Wusong River give the displacement away.

Apple Maps also mismatches satellite imagery and road maps in China. Credit: Apple Inc.

The misalignment does not appear on the Chinese version of Google Maps, since both the imagery and the map use the state-mandated coordinate system. Users can pinpoint the correct location of the monument on both sources by searching for the GCJ-02 coordinates (31.2423 N, 121.4914 E). Similarly, maps from the Chinese company Baidu line up correctly. In addition, manufacturers evidently modify GPS devices sold in China to align with GCJ-02 maps. “It is still unclear whether GPS chips manufactured in China return GCJ-02 coordinates directly to match approved Chinese maps, or if they return WGS-84 coordinates, which authorized map software providers can convert to GCJ-02,” a Wikipedia article on the subject states.

The Chinese version of Google Maps shows the monument in the correct location on both the imagery and the street map when a user searches for its GCJ-02 coordinates. Credit: Google Inc.

However, because the cartographic regulations do not apply in the special administrative regions (SAR) of Macau and Hong Kong, Google will always scramble the map at the borders of these SARS and mainland China.

Google Maps near the Hong-Kong-Shenzhen border. Credit: Google Inc.

February 8, 2016

Gaia GPS How-To

How to Read a USGS Topo Map

by Kate Dougherty December 19, 2015

written by Kate Dougherty

Classic 7.5 minute USGS topographic map for Manitou Springs, Colorado, 1961. Credit: U.S. Geological Survey.

We recently covered the basics of topographic maps, including how to read contour lines, and how to use the maps to plan your next outing. In this post, we’ll go into more detail about U.S. Geological Survey (USGS) topo maps.

How to read a USGS Topo

The USGS has been the definitive source for U.S. topo maps since the 1880s. Often referred to as quadrangle maps, or quads, the most commonly used USGS topo maps have a scale of 1:24,000 and cover 7.5 minutes of longitude by 7.5 minutes of latitude. In apps and on the Internet, the quads get scanned into digital files and seamed together into one continuous quilt, making them potentially less crisp and clear than modern topo maps based on OpenStreetMap (OSM).

The USGS prints wider index contour lines for easy visibility, and typically measures maps in feet. Contour intervals vary by map, depending on the area’s relief. In some cases, mountainous regions may have an interval of 50 feet, while other maps covering relatively flat areas might measure intervals every 100 feet instead. On paper maps, you’ll always find the contour interval printed at the bottom. You can display USGS topos in Gaia on iOS and Android.

Check out the guide to USGS topographic map symbols for more information about identifying map features of this source.

Selected USGS topographic map symbols. Credit: U.S. Geological Survey.

USTopo

Established in 2009, the USGS calls USTopos their next-generation version of USGS topo maps, and the maps use seamless digital data, while adhering to the quad format. USTopos show contours, roads, built areas, water, mountains, and labeled trails.

Since the USGS does not field-verify the newer, digital topos, they often show fewer trails, remote roads, campgrounds, survey markers, and boundaries than legacy USGS topos. USGS revises these maps every three years to include additional data as they collect and vectorize it.

The National Map

On the Web, you can locate and download many types of maps and satellite images through The National Map, including individual topos. Apps like Gaia GPS also tap into The National Map service to provide a seamless view of the newest USTopos in the palm of your hand.

Learn how to display The USGS National Map in Gaia on iOS and Android.

Forest Service Topo Maps

USFS topo maps (FSTopos) use the same format as the USGS – 1:24,000-scale, 7.5-minute topographic map series, but with enhancements and regular revisions contributed by USFS field staff that emphasize forest-related information. For example, while USGS topos outline national forests in pink, FSTopos color their complete footprints in a light grayish-pink to make them stand out. These topos direct our attention to trails, roads, and water features by toning down wooded areas and contours.

Excellent trail coverage and prominently marked Forest Service road numbers (helpful for navigating backcountry areas) make these maps extremely valuable for outdoor recreation. While revisions as recent as 2015 make the FSTopo more up-to-date than the USGS equivalents, this source only covers quadrangles containing national forests or grasslands.

Manitou Springs, Colorado FSTopo map. Credit: U.S. Geological Survey and U.S. Forest Service.

Now that You Know How to Read U.S. Government Topo Maps

You may also want to read about OpenStreetMap-based topo maps, and experiment with all of these sources in Gaia GPS as you organize your next trek. Follow the iOS and Android links throughout this post to learn how to use them in the app.

If you have any questions about using topo sources in Gaia, please email us at support@gaiagps.com.

December 19, 2015

Gaia GPS How-To

How to Read OpenStreetMap Based Topo Maps

by Kate Dougherty December 19, 2015

written by Kate Dougherty

While we’ve covered how to read a topo map and U.S. Geological Survey (USGS) topographic maps in particular, OpenStreetMap-based topos are increasingly popular resources that merit their own post. In this post you will learn how to read OpenStreetMap-based topo map.

The OpenStreetMap (OSM) project leverages the knowledge of millions of people around the globe to crowdsource detailed world maps. As community involvement increases, OSM grows in detail and continues to improve—learn how you can help update OSM data in our recent blog post. Since OSM data is free to use, many apps and websites use it create custom maps for specific audiences.

OSM-based maps have higher resolutions than traditional USGS topos. They often provide more details than newer USGS topos, including additional feature types like cycle paths, bridleways, cable cars and chair lifts, brownfields, and better trail coverage to boot. Note that while USGS typically labels elevations on the 1:24,000 scale maps in feet, OSM-based maps label in meters.

OpenCycleMap

OpenCycleMap, one example of an OSM-based topo map service, emphasizes existing and proposed bike trails, bike lanes, and other amenities for cyclists. While it adds contours and hill shading to the standard OSM map, OpenCycleMap still generally offers less detail about the terrain, such as land cover types.

OpenCycleMap adopts elements of the OSM style, like purple/blue dashed lines for cycling paths and pink dashed lines for footpaths, though they appear more prominent than in OSM, “bolded” even. Non-cycling features have a lighter appearance, with footpaths left unlabeled.

This map source shows national and regional cycling routes, local cycling networks, and footpaths. It also displays bicycle shops, bike parking locations, restrooms, bars, pubs, and cafés near cycling routes.

OpenCycleMap display for the Manitou Springs, Colorado area. Credit: ThunderForest and OpenStreetMap contributors.

OpenCycleMap pulls the latest data from OSM every couple of days. A variety of apps and websites pull OpenCycleMap data, including Gaia GPS. Learn more about OpenCycleMap symbols through the key.

OpenLandscapeMap

OpenLandscapeMap by ThunderForest, another OSM-based service also found in Gaia GPS, focuses on terrain. Like OpenCycleMap, OpenLandscapeMap tones down non-naturally occurring features like roads, which all appear as light purple. Some other differences include:

less differentiation for trails
increased detail for land cover types ( like scrub, grassland, and farmland
darker and more prominently displayed water features
more labeled natural features like springs and geysers

OpenLandscapeMap also marks mountain peaks with a triangle, and labels their names and elevations, unlike the less specific USGS topos.

OpenHikingMap

OpenHikingMap styles OSM data to create a map geared toward hikers. We wrote about OpenHikingMap when it was first released in 2013. This map labels trail names and peak elevations. It also shows protected areas, restrooms, parking lots, and several different land cover surfaces.

Now that You Know How to Read an OpenStreetMap-Based Topo Map

You may want to try these sources out in Gaia GPS as you brainstorm your next foray into the great outdoors. Follow the iOS and Android links throughout this post to find out how to use them in the app.

If you have any questions about using topos in Gaia, just email us at support@gaiagps.com.

December 19, 2015

Gaia GPS How-To

How to Read a Topo Map

by Kate Dougherty November 16, 2015

written by Kate Dougherty

Topo maps use concentric “contour lines” to show elevation changes, and help people navigate mountains and wilderness areas. The denser the contour lines appear, the steeper the terrain. Topographic maps also tend to show a wealth of natural information, like markings for trails, springs, forests, and swamps, though they tend to include roads as well.

In this post, you’ll learn how to read a topo map, as well as how to use topos to plan outdoor adventures. We touch on a variety of topo maps, including United States Geological Survey (USGS), U.S. Forest Service (USFS), and OpenStreetMap (OSM) topos.

Comparing Topo Maps

Overview	Features	Coverage & Units
USGS Topos (Classic) The industry standard for topographic information. Possibly still the best topo for hiking.	Built areas and man-made features Land cover types Water Labeled trails Natural landmarks MayContours are toned down compared to newer USTopos, making other features easier to see.	Feet* Covers the US
USGS Topos (USTopo) “Born digital,” next-generation USGS topo maps published since 2009. Based on seamless digital data, but presented in a familiar quad format. These often have fewer features and less detail than legacy USGS topos. Revised every 3 years.	Contours Built areas Roads Water Labeled trails Mountains Can be missing trails, remote roads, campgrounds, survey markers, and boundaries.	Feet* Covers the US
FSTopo USFS-based topos with forest-related enhancements. Often more detailed and up-to-date than USGS topos. Only available for quads containing National Forests or Grasslands.	National Forests and Grasslands Forest Service roads Water Natural landmarks Labeled trails and trailheads	Feet* Covers US National Forests
The National Map MayService provides a seamless view of USTopos for use in apps and on the Web.	Contours Roads Built areas Water Mountains Labeled trails May be missing trails, remote roads, campgrounds, survey markers, and boundaries.	Feet* Covers the US
OpenLandscapeMap MayStyles OSM data to accentuate natural features. Good for rural and backcountry areas.	Contours Rivers, creeks, and streams Springs and geysers Mountain peaks Unlabeled trails	Meters Global
OpenCycleMap Styles OSM data to enhance cycling features.	Cycling routes Cycle paths and bike lanes Bike shops Unlabeled foot paths Restrooms Cafes and restaurants	Meters Global
OpenHikingMap Styled OSM map for hikers.	Labeled foot trails Protected areas Land cover types Peak elevations Restrooms and parking lots	Meters Global
Gaia Vector Topo Worldwide topo map based on OSM data, styled like USGS topo maps.	Roads Rivers Runways Islands and islets Military areas Natural features like plateaus, peaks, and volcanoes Amenities like toilets, viewpoints, water fountains, and picnic areas	Feet Global

*Meters in Puerto Rico

What are Topo Maps Used For?

Topo maps provide a bird’s-eye view of a particular area and help you orient yourself in the landscape based on local landmarks. An essential tool for backpacking, hikers use topos to avoid very steep ascents, figure out how to split up multi-day hikes, and determine the right amount of supplies. Topos can also indicate the need to ford a stream, as well as warn you away from dangerous areas like mines, depressions, bogs, and submerged rocks in lakes and streams.

More than just a tool for recreation, topo maps serve conservationists, firefighters, and other professionals who either study the environment or work outdoors. Architects and planners also use them to assess potential build sites.

How to Read Elevation Contour Lines

Contour lines indicate changes in elevation—they act as a 2D tool for visualizing landscapes in 3D. Contour lines show the shape of the terrain, including its hills, slopes, and depressions, by connecting points of equal elevation. If you follow a line, you’ll stay at the same elevation. When you cross a line, elevation either goes up or down.

Think of contour lines as imaginary horizontal planes sliced through the terrain surface. It may be helpful to visualize them as stacked “layers” of the landscape, similar to a layer cake. Lots of contour lines clumped together mean a lot of elevation change, or a steep slope. A large mountain appears as a dense group of lines with a small circle in the center that represents the peak—just picture looking down at a wedding cake from above. Areas with few contours appear relatively flat—more like a 2-tier birthday cake.

Cartographers often use brown hues for contour lines, and they label every fourth or fifth line with the elevation it represents to serve as an “index contour.” They often style index contours thicker or bolder, to make them easier to see. The non-index contour lines give more detail about the landscape, but lack labels usually.

The contour interval, or amount of elevation change between each line, varies from map to map. To figure out the interval, look at the labels for two consecutive index lines and subtract the lower number from the higher number. If the map labels every 5th line, divide by five. For index lines occurring every 4th line, divide the difference of the two numbers by 4.

In addition to contour lines, some modern topos like OpenCycleMap add hill shading, which makes it easier to visualize the terrain in 3D.

Features on Topo Maps

Best known for emphasizing naturally occurring features such as mountains, streams, springs, and land covers, topographic maps also show administrative boundaries, roads, churches, cemeteries, rail lines, and campgrounds.

Topos utilize colors, patterns, and symbols to indicate different features. USGS maps, for example, use light green for parks, light blue for water, brown for contour lines, bright red for major highways, and dashed black or gray lines to represent trails. Typically these features have labels of the same color.

To learn more, check out our post about USGS and other U.S. government topos.

Classic 7.5 minute USGS topographic map for Manitou Springs, Colorado, 1961. Credit: U.S. Geological Survey.

OpenStreetMap-Based Topos

OpenStreetMap (OSM) crowdsources detailed maps of the world. Many apps and websites stylize OSM-based data to accentuate specific features specialized for a particular audience.

Drawn in a modern style, OSM-based maps offer a higher resolution that increases zoom potential. OSM-based sources often have more details and more feature types than newer USGS topos, such as improved trail coverage. Note that while USGS typically labels elevations on the 1:24,000 scale maps in feet, OSM-based maps are labeled in meters.

To learn more, read our post on OpenStreetMap-based Topo Maps.

Gaia Vector Topo

Gaia GPS develops a worldwide topo vector source based on OSM, styled like the USGS topos. Unlike other tiles-based sources, vector maps get styled and drawn directly to the device. Because the map gets rendered locally, it appears crisper when zooming, and provides better text readability—the smaller download size doesn’t hurt, either.

Now that You Know How to Read a Topo Map

We encourage you experiment with all of these sources in Gaia GPS as you plan your next adventure. Follow the iOS and Android links throughout this email to view our Knowledge Base articles about adding these map sources in the app.

If you have any questions about using topos in Gaia, just email us at support@gaiagps.com.

November 16, 2015

Gaia GPS

Use Your GPS Tracks to Update OpenStreetMap

by Kate Dougherty September 14, 2015

written by Kate Dougherty

In a recent blog post, we showed you how to join OpenStreetMap and help build an open map of the world, alongside millions of other map editors. That post focused on editing the map by comparing it to aerial imagery.

This new article covers how to use your GPS recordings (such as those you might make in Gaia GPS), to edit roads, landmarks, and other information into the map. Remember, OpenStreetMap doesn’t just mean roads – it includes trails and everything else of interest to hikers.

Record GPS Tracks and Waypoints

First, you need to go take a hike or something similar, and record tracks and waypoints. With Gaia GPS:

Download maps (iOS/Android) of the area you plan to explore ahead of time so they’ll be available without a strong internet connection.
Start recording (iOS/Android) your track.
It’s easy to add photos along your route (iOS/Android); the app will automatically geolocate or “attach” them at the proper locations.
After you’ve finished recording your track, you’ll see a waypoint pin at the location where the photo was taken. Simply tap the pin to see your photo.
You can use your photos to contribute to OSM too, but we’ll leave that for another post.

Completing Your GPS Track

Once you’ve finished recording your track, you’ll have the option to customize its name (iOS/Android) and add it a folder (iOS/Android). If it’s one of several trails you plan to hike in Yosemite, for example, touch the folder icon to add the track to a new “Yosemite” folder.

Gaia GPS will save your track and edits automatically, so there’s no save button on this screen. When finished, use your Android’s built-in back or undo button or tap done on an iOS device to exit the window and go back to your map.

Next, export the GPX file for your track. You can do this from within the app (iOS/Android), or by downloading the file from GaiaGPS.com. By default, your data will sync to gaiagps.com anytime you launch the app when connected to the internet.

Uploading Your GPS Track to OpenStreetMap

While OSM won’t automatically convert your track into a trace on the map, contributors can use it as a guide to add it manually. You can either trace over the path yourself, or make it public so other editors can access it.

Log into OpenStreetMap at http://www.openstreetmap.org.

Click GPS Traces at the top of the screen. You’ll see a list of the most recently uploaded traces.

Click Upload a trace at the top of the screen.

Click on GPS Traces at the top of the screen to upload your file to OSM.

You’ll see a list of the most recently added traces. Click Upload a trace to add yours.

On the next page, browse to select the location of the GPX file on your computer. You can also include a description, add tags, and set its visibility to Public. Click what does this mean? next to the visibility drop-down for more information on visibility types.

Click upload (the upload button is hidden by the dropdown in the screenshot below).

Select and describe your file, then set its visibility.

You’ll receive a confirmation of your submission, and a message saying that you’ll be notified by email once it’s been added to the OSM database. This usually happens within a few minutes. When you receive the email, click on the link to see the OSM page for your trace.

Your track’s page on OSM. Click edit to start editing the map at that location.

Using Your Trace to Edit OpenStreetMap

Next, click edit to view your track superimposed over aerial imagery within the default editor. The track is so detailed that it may seem difficult to trace. But not to worry – OSM actually has three editors. One of them, Potlatch, will automatically smooth out and simplify the line.

To view and edit your trace in Potlatch, click the down arrow next to the Edit button at the top of the screen, then select Edit with Potlatch 2 (in-browser editor). You can also follow these steps to access Potlatch directly from your file’s OSM home page.

Your track is superimposed on top of imagery in the default OSM editor.

While Potlatch looks different from the default editor, it works in much the same way. OSM displays basic instructions at the bottom of the screen.

The trace is simplified in the Potlatch 2 editor.

Simply click on a blank (unmapped) area of the map to start drawing a new way. Since your trace isn’t officially part of the map yet, OSM considers it a blank space.

Click on your track’s starting point to begin tracing over it, and click to add nodes where it begins to turn. The Potlatch editor makes this process much easier. Since Potlatch smoothes out your track, you’ll need fewer nods and less time to trace it.

Follow your track to add it to the map as a new feature.

When you’re finished tracing, press enter on your keyboard (or double-click on the last node).

Next, you’ll need to add tags on the left. While the left panel may seem a bit crowded and complex when compared to the default editor, the idea is the same, except that Potlatch uses icons to offer a quicker, more visual way to tag features.

Set the feature type. Click Unknown, then choose Paths, then Footpath.

Tag the new feature.

There are several tabs in the left pane; the first two are the most relevant to my path through Ringing Rocks Park.

After adding basic information on the first tab, click on the second tab and add a tag for the Surface field. In the example below, I’ve tagged the trail as an unpaved surface.

Feel free to explore the remaining tabs and add more information.

Click the Save button at the top of the screen to save your edits.

You’ll be prompted to add a description of your edits for the community. For example, I wrote: “Added the trail/footpath that goes through Ringing Rocks Park.”

Be sure to tweet or Facebook your edits to get your friends mapping too.

Check back a bit later, and voila, your travels are now on the map for all to see!

Your track is now mapped and visible to millions of users.

Learn More about Uploading GPS Traces to OpenStreetMap

Recording, uploading, and using your GPS tracks to contribute to OpenStreetMap is really quite simple and fun. You may just find yourself wanting to know more. Here are a few resources:

We’re looking forward to seeing your traces on OpenStreetMap!

September 14, 2015

Gaia GPS

Map Your World with OpenStreetMap

by Kate Dougherty August 24, 2015

written by Kate Dougherty

Map your favorite places, and join a global movement that makes data free and open to all people. This guide will teach you to edit OpenStreetMap (OSM).

OpenStreetMap: More Than Roads

Whether you’re hiking in the woods or driving in town, you can edit the map near you to make it accurate and more complete. OpenStreetMap uses the local expertise of contributors to crowdsource detailed maps of the world, and anyone can use the data, provided they credit OSM.

Started in 2004, the number of OSM editors has grown from 1,000 on Christmas Day 2005, to more than two million today. The services now gains an average of 8,000 new users each month. OSM reached 20 million edits early last year, and its explosive growth shows no signs of slowing.

Reasons to Edit the Map

People contribute to OSM for all sorts of reasons:

Remote Forests and Trails – While U.S. government agencies like the U.S. Geological Survey provide topo maps to the public for free, the governments of other countries charge a fee for their maps. People have banded together to make free – and sometimes better – maps through OSM.
Local Maps – Some contributors want good local maps. For example, the OSM map of Berlin is probably better than any map in the world, because the Germans love OSM.
Crisis – In crisis, mappers pool their efforts to improve the OpenStreetMap so that first responders and emergency aid workers can navigate the affected areas.

And from personal experience, you feel a bit like a better person when you edit the map.

Getting started with OpenStreetMap.org

In the following example, I’ll show you how I made some edits to my own neighborhood.

The first step is to create an account with OSM at http://www.openstreetmap.org/. There are other tools you can use to edit the map, but this is the most common way.

Explore an Area

Enter an address, zip code, or city to search for the area you want to explore. Or, just click the Show My Location button (the arrow below the zoom controls on the right).

Your search results will appear on the left.

The map will center on your chosen location on the right; the place’s tags (attributes, or descriptive information) are shown on the left.

You may not recognize many of the tags, but don’t worry… editing is simple.

Editing OSM

Now, you’ll need to find something that needs to be added or changed. When I first registered with OSM, I didn’t know where to start, but after poking around for a few moments, I found plenty to do.

The basic steps are:

Click the Edit button at the top of the screen to enter edit mode. Microsoft Bing aerial imagery will load in the right pane, with existing OSM features superimposed on top.
Trace over the imagery to add roads, buildings, and other missing features.

I recommend you go ahead and do the built-in walkthrough on openstreetmap.org. Then jump in and improve the map near you.

Editing From the Field

We’re focusing here on using aerial imagery to help improve the map. But another way (and some say the pure way) to improve OSM is to collect data directly from the field.

Here are ways you can collect data to help edit OSM:

Go find out the name of a feature on the map. While tracing from imagery is helpful, tagging new features adds a whole other dimension to the data.
The next time you’re out on a trail, record what you can do there (hiking, biking, horseback riding, etc.)
Mark the exact coordinates of features in the field, using an app like Gaia GPS
Record hikes and drives of unknown roads and trails with GPS apps

Since aerial imagery can be years old, your tracks and waypoints will provide the most up-to-date information for OpenStreetMap. See the end of this article for a list of resources and tools to help you edit the map.

Editing from Imagery

Look at minor roads in off-the-beaten path areas. Parks are another good place to start, since many of them lack information for restrooms, foot paths, playgrounds, and other features. You’ll get a kick out of this, and spend more time than you think fixing your local haunts.

I started by homing in on a local ball park, and found neither the baseball diamond, nor the park road featured on the map.

Adding New Features

To add a new feature, you’ll use the tools at the top of the right pane.

The Point tool drops a map marker at a point of interest.
The Line tool traces roads, rail lines, trails, bike paths, footpaths, and other linear features.
The Area tool lets you add detailed footprints of buildings, schools, businesses, lakes, swimming pools, and more.

No matter which tool you choose, you’ll want to zoom in far enough to be able to mark features accurately.

Line features, as they appear in OSM.

Adding a Road or Path

In this example, I’ll add the minor road with the Line tool, and the ballpark with the Area tool.

To begin adding a road or path (what OSM calls a “way”):

Select the Line tool at the top of the right pane. Bear in mind that a line should run down the center of the surface. If you’re adding a road, your line should connect to another road that’s already mapped in OSM.
Click on the point where the center of the new road connects with an existing road. This will create the first node, or point that helps define ways and shapes.
Follow the course of the road; where it begins to turn, click to anchor a new node that will allow you to swivel and follow its shape.
Press the enter key (or double-click on the final node) to complete your line. You’ll have a burgeoning sense of accomplishment, but you won’t be finished quite yet.

For this example, I connected the new road where it begins at Karakung Drive, and traced it to its dead end at a parking lot. Your sketch doesn’t have to be perfect, but if you make a mistake, use the undo arrow at the top of the screen. You’ll be an expert at tracing features in no time.

Next, you’ll be prompted to add a feature type for the new road.

Set the Feature Type to “Road,” then select a subtype (Residential Road, Motorway, Primary Road, etc.). Click the information icon (i) for a description of each type.
If you’re not sure what to choose, set the type to Unknown Road. (If you’re adding a path, choose Path as the feature type, then select the appropriate subtype.)

Then, name and tag the road:

Add the name of the road or path. Since the road that goes through the ballpark is unnamed, I left that field empty.
By default, roads are assumed to be two-way. If your road is one-way, change the value in the One Way field. Add the speed limit, if known.
You can indicate which types of traffic are permitted in the Access section. If you’re not sure, leave this section empty.
You can also note the type of surface in the Surface section. Most roads are tagged as paved, which means the surface is sealed with asphalt, paving stone, metal, or other material. If you know the surface is asphalt, you can specify that here. If you’re not sure, tagging more generally as paved or unpaved is fine.
If you like, you can include additional fields, such as address, phone, and website with the Add field drop-down menu.
Finally, be sure to save your edits with the button at the top right.

Afterwards, OSM will prompt you to write a short summary of your changes in the left pane. For example, you could write something like “Added a minor road and speed limit.”

Adding a Park or Building

I added the baseball diamond outline. You may want to add a body of water, grove of trees, your place of work, or a favorite restaurant.

Select the Area tool at the top right.
Click on a corner or edge of the feature to place the first node.
Continue tracing around the feature; you’ll see a polygon taking shape as you go.
When you’re finished, press enter to complete the shape.

OSM offers tools to help you smooth out your tracings. While they won’t help you if you’re tracing a ballpark, they can make outlining buildings and other features a lot easier.

If your square, rectangular, or circular sketch is an “approximate” one that could use a bit of help, complete the drawing, then click on it. A menu of tools will appear on top of your sketch. Click the square-shaped tool (Square Corners) to fix up square and rectangular shapes, or the circle-shaped tool (Make Circular) for circular ones.

Add tags for the new feature in the left pane.

I searched for “baseball” in the search box at the top left, then set the feature type for the ballpark to Baseball Diamond.
I entered Reilly Field as its name.
Since I didn’t know if the park is lit or not (probably not, and I don’t see light poles on the imagery), I kept the value in that field as “unknown.”
I also added the address and the website for Haverford Township Little League.
Don’t forget to Save your edits, and then summarize them in the left pane.
Also, make sure to Tweet or Facebook your changes, and get your friends mapping too.

Your Edits Reach Millions

It may take a few minutes (or hours in some cases) before your edits appear on OpenStreetMap.org, and start to percolate out to other maps and services that use OSM data. When you edit the map, your changes will start being pulled by all of these apps and maps used for so many things, used for fun and for research and for work.

Hundreds of millions of people use OpenStreetMap each day. OpenStreetMap data powers some of the best websites and apps out there, including our own Gaia GPS. Here are a few others:

The newly added features, as they appear to OSM users.

Become an OSM Expert

There are several resources to help you get started with OSM. Learn more at these sites, and happy mapping!

Video Tutorials
Beginner’s Guide – A community-maintained guide for beginners.
OpenStreetMap Wiki – Need help with tags? Get detailed keys, descriptions, and documentation here.
OpenStreetMap Help – post a question; get an answer.
FieldPapers.org – This tool makes collecting data from the field and updating OSM easy. Print off atlas pages in advance, sketch and annotate what you see, then upload the photos of your notes. Open your updated Field Papers file in OSM to start editing, based on your firsthand experience.
Track-Making Apps – a list of iOS track-recording apps that can be used to update OSM.
Recording GPS Tracks – OSM’s instructions on how to edit the map by uploading GPS traces.

August 24, 2015

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Kate Dougherty

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Learn More about Uploading GPS Traces to OpenStreetMap

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Reasons to Edit the Map

Getting started with OpenStreetMap.org

Explore an Area

Editing OSM

Editing From the Field

Editing from Imagery

Adding New Features

Adding a Road or Path

Adding a Park or Building

Your Edits Reach Millions

Become an OSM Expert