Safecast Web Map Update

Check out the new Safecast Tilemap!

While quite a few people depend upon Safecast’s open-source iOS and OSX native apps for investigating radiation levels around the world, our web-based tilemap undoubtedly gets the most use. Because it’s accessible to anyone with an internet connection and from any web browser, it’s extremely convenient. It’s also automatically updated several times a day, so it will display the most current data without the need for a manual refresh. Like every aspect of the Safecast project, the tilemap is a work-in-progress, continually being revised. This most recent update, however, is a major one, and brings numerous usability and customization enhancements. Most of the credit is due to Nick Dolezal, who originally developed this map as well as our primary apps (in fact it was his work with an earlier iOS radiation app called GeigerBot, which is still available, that brought him into our orbit). But as with everything at Safecast, lots of people have contributed in some way, either with supporting code, aspects of the visualizations, localization, and testing. There’s a long list of acknowledgements in the map’s “about” box, but truth be told, this is mainly Nick’s baby and we’re all in awe of his knowledge and ability.

Since its earliest versions the tilemap has always had a customizable display.  It included, for instance, selectable layers for different datasets and for different map underlays. Gradually other features were added, such as the ability to load and display specific log files individually or as groups, to show Pointcast realtime sensors and their data, and a handful of other visualization tweaks. Most of these were accessible from drop-down menus, while others required entering specific codes into the url string. This recent update adds a few new features, but its primary purpose is to make all of the customization features easily accessible in a single panel.

Here’s a rundown of what’s new and how to use it:

On launch:


When the Tilemap is opened in a browser, by default it will be centered on Fukushima, with both the most current datapoints and interpolation enabled, and Pointcast sensors displayed. The basemap is Google’s standard map. The update adds a control in the upper left corner to show and hide the new control panel.

Panel open:


The panel shows from top: search panel; toggle for the crosshair reticle; layer list partially expanded; language selector and info links; basemap list collapsed; and advanced features controls collapsed.  We’ve been experimenting with which features should be on by default and which should be “sticky” and carry over from session to session. Don’t be surprised if a few of them change in the future.

“Find Address”:

This is a standard location name search panel, which routes through Google’s API. It allows multilingual searches.



This toggles the crosshair reticle on and off. It is initially on by default. The reticle displays the radiation reading from the point it’s centered on in μSv/hr (microsieverts per hour). Note that this menu item and most of the others have an animated visual tooltip which shows what it controls.


tilemaplayersexpandall01markThis initially appears in a partially expanded state, allowing the user to select either the most recent Safecast data (the date of the update is indicated in a box to the right of the name), or to open the Safecast Snapshots panel, which allows displaying a time-based selection of data (see below). The “List All” toggle displays the entire list of available data layers. The caret mark collapses the layer panel itself.

When fully expanded, the Layers panel gives complete access to groups of Safecast data individually, as well as to other open-source radiation datasets and Pointcast realtime sensors. It also gives access to the feature for displaying selected Safecast log files.

Safecast data layers:

As mentioned above, by default the map opens with the “Safecast” layer selected, which includes the full set of current measurements displayed as both points and interpolation.  This menu allows either points or interpolation to be displayed individually.

Safecast Snapshots:


This is a much-requested feature for showing how radiation levels have changed over time, which was implemented earlier this year. Clicking the menu item will open a small panel with a slider which allows 6-month data “snapshots” to be displayed one at a time. The changes are particularly visible when looking at the Fukushima region. Not every location has been covered in every 6-month period however, so it’s not always possible to obtain a direct comparison.

Safecast Points:

There are two menu items, one of which displays all data points gathered until April 2013, another until March 2014. While largely superseded by the Safecast Snapshots, which provide greater control, these are still useful because they are cumulative to the date indicated.

Other open-source layers:

We have continually kept an eye out for other open-source radiation datasets, and have included several as layers in previous versions of our maps. So far the ones we have found have all been from official government agencies. They include: DOE/NNSA Fukushima overflight and mobile data from mid-2011; USGS/GSC natural terrestrial background for the continental US; Geoscience Australia natural terrestrial background; and AIST/GSJ natural terrestrial background for Japan. More layers will be added as appropriate datasets are identified and obtained.

bGeigie Logs:


These menu items provide access to a feature first implemented in 2015, which allows Safecast log files to be viewed individually or in groups.



This opens the bGeigie Logs search panel. A number of options are offered.  The most common method is to enter the 5-digit bGeigie log id number. Logs can also be selected by a date range, or by user ID, status, subtype, etc.. Once the search parameters have been entered, click “search,” and the database will process the request and display the data as a series of large dots. Processing might take a few minutes if a lot of data is requested.

Add Cosmic Logs:

Quite a few Safecast volunteers log radiation data on airline flights, but this is not normally displayed on the Safecast map. There is now a “subtype” selector when data is uploaded which includes “cosmic” radiation, and the “Add Cosmic Logs” menu item allows all of these logs to be displayed at once. Selected cosmic logs can also be displayed by entering appropriate search parameters in the “Search” panel. (Please note that cosmic radiation is complex and cannot be directly equated to cesium-137, for which bGeigies are calibrated. Actual dose rates may be much higher. IRSN is currently conducting in-flight tests to see if we can characterize these differences better.)

Remove all:

This menu item duplicates a control inside the “Search” panel, and clears all selected log file data from the map display.


This also duplicates a control inside the “Search” panel which provides several options for displaying the measurement point dots.

Realtime :


By default, Safecast’s Pointcast realtime sensors are displayed on the tilemap, and clicking on them displays recent data readings and provides access to more information (see the blog post Pointcast Rollout, Part 1 for a complete explanation). The “Radiation Sensors” control toggles the display of these sensors on and off.




Currently allows the interface to be switched between English and Japanese, with more languages in the works. The interface will change immediately, but the new language setting will not be applied to the Google Maps labels themselves until this page is reloaded.

About this map:

This opens an info panel which gives a complete list of contributors, data sources, methodology, release notes, etc..


Opens the donation page at  Please donate!


Opens the Safecast blog page at



When expanded, this provides extremely useful choices for the basemap underlay to suit different uses and needs. Currently 12 options are provided, including four open-source maps as well as simple black or white underlays. The animated tooltips provide a good indication of what each underlay map looks like.



The advanced options include many that turn map items off or tweak the display to make it easier to take screen shots etc.:

Map Scale:

Toggles the vertical radiation level color scale on and off. It is currently off by default.

Zoom Buttons:

Toggles the “+” and “-“ map zoom buttons on and off. On most systems, the map can still be zoomed without the buttons by using a scroll wheel, pinch gestures, or similar affordances. The buttons are on by default.

High Res Tiles:

Displays data point tiles at a higher resolution, which smooths their edges when zoomed far in, and makes them display thinner when zoomed out. On by default.

NN Tile Scaler:


This option is intended for screenshots and press images. It allows the data point tiles to be viewed beyond their normal zoom range by overriding the browser’s image scaling and applying a separate nearest neighbor interpolation. On by default.

Tile Shadow:


Applies a drop shadow to the data points. Primarily intended for screenshots and press images, this can significantly improve contrast between the datapoints and the basemap, but only at a significant performance hit.

Query API @ Center:

As in previous versions of the tilemap, it is still possible to obtain a list of data measurements at any location by right-clicking and selecting “Query API.” This new feature replicates that functionality for users of mobile devices by querying at the center of the crosshair reticle. As before, the API query results will open in a new browser window where their search parameters can be refined.

Final Comments:

As we said above, we intend to continue to add features and implement as many user requests as possible. This is just the first iteration of the Safecast tilemap control panel interface, and we gave a lot of consideration to how to design it so that new features can be added easily without disrupting the most commonly used functionality. As always, we welcome feedback.