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Introducing Leaflet Blurred Location Display Library .

by sagarpreet | 9 months ago | 5 | 5

Hello everyone ,

Public Lab takes utmost care in making sure that the location of a person is exposed to the extend he/she wants . Hence we here at Public Lab are working on giving people the power to safely share their location on the web .

I am happy to announce two new libraries that we are working for the past few weeks that helps in achieving this vision of ours .

In this post , i wish to introduce these new Public Lab open source software projects on Location Privacy .

Leaflet Blurred Location Display :

Leaflet-blurred-location-display (LBLD) is an extension of leaflet-blurred-location (LBL) and does the following:

  • Cleverly displays your location, keeping your privacy settings in mind .
  • Color code the markers on the map according to the precision .
  • Shows heat map to analyze number of people at different rectangles of the grid .
  • Fetches data from remote API or you may pass array of coordinates directly into LBLD API .

The demo is live :

1.) Shows Public Lab users location :

2.) Shows how some locations (markers) are not shown at different zoom levels :

So at Lower zoom levels , irrespective of the precision of coordinates you shared - your marker is visible on map . But as you zoom in to higher zoom levels , lower precision markers are removed .

To see details on how to use the LBLD library in your project , jump over to our github page :


1.) Lower the precision , Greater the privacy :

The red markers corresponds to coordinates [23.1 , 77.1] , [20.1 , 76.1] having precision of 1 . At lower zoom level 5**** , these red markers are visible on map . image description

But as you zoom in to level 6 , these red markers are removed from the map whereas other high precision markers are still visible .
image description

2.) Color Coding of the markers :

image description

According to the precision of the coordinates , different colors are given to the markers .

Precision = 0 , Blue colored markers .

Precision = 1 , Red colored markers .

Precision = 2 , Orange colored markers .

Precision = 3 , Green colored markers .

Precision = 4 , Black colored markers .

Precision = 5 , Grey colored markers .

Precision >= 6 , Yellow colored markers .

Also clicking the markers shows a pop-up telling the precision :
image description

3.) Heat map :

Greater the markers in a region , Darker the color .

We wanted to give an easy visualization power , so we implemented this grid heat map .

image description

The default color of grid is : #F3F0C0

If number of markers are in range [1,10] , the color is : #FFA500

If number of markers are in range [11,15] , the color is : #faff05

If number of markers are in range [16,25] , the color is : #FF6347

If number of markers are in range [26,35] , the color is : #FF4500

If number of markers are in range [36,45] , the color is : #FF0000

If number of markers are greater than 45 , the color is :#8B0000

NOTE : Clicking on each rectangle shows the pop-up showing number of markers in that rectangle .

4.) Custom API and JSON parser :

You can pass your own API link to fetch data and show it on the map . Also you need to pass a JSON parser function to parse your API . See our Github page to know more details !

Blurred-Location library :

A JavaScript library to help manage variable location privacy through a "blurred location" model .

This library is an independent module which gives many mathematical functions that one can use on any map (not necessary Leaflet map!) . The library is thoroughly tested using Jasmine framework .

Jump over to the github page for more details of each mathematical function :

The npm link is :

If you have any suggestions or any doubts regarding the use of this library , kindly open an issue here .

I personally thanks @warren for mentoring me and giving all these awesome ideas .

Sagarpreet Chadha

Thank you :)

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Software Community Growth through "first-timers-only" issues

by gauravano | 9 months ago | 15 | 7

first-timers-only issues are those which are written in a very engaging, welcoming way, far different than the usual "just report the bug" type of GitHub issue. To read more about these, check out, which really captures how and why this works and is beginning to be a movement in open source coding outreach! Beyond the extra welcome, this also includes getting such well-formatted issues out in front of lots of people who may be contributing to open source software for the very first time.

It takes a LOT of work to make a good issue of this type, and we often walk through each step required to actually make the requested changes -- the point is to help newcomers understand that a) they're welcome, and b) what the collaboration workflow looks like. Read more at !

Since early 2016, we at Public Lab are working to make our open source software projects more welcoming and inclusive and to grow our software contributor community in diversity and size. Creation of First-timers-only issues was also started at Public Lab near the end of 2016 -

Now, as GSoC, Outreachy, and other outreach programs are seeking proposals for the upcoming summer, we put a lot of extra time and work into welcoming newcomers into our community and making sure they are well-supported. We've seen a huge increase in newcomers and wanted to report in about how this process has scaled!

Till now, nearly 409 FTO issues has been created across our projects which shows how many people have been welcomed in the Open Source 🌐 and in our community by the collaborative efforts of all of us.

From March 9, 2019, we started maintaining the list of people who want to work on various projects of Public Lab - through first-timers-only issues. And, we are proud to announce that in past 20 days, we all have created 55 FTO issues i.e., 13% of total Public Lab FTO issues(from beginning) are created in last 20 days. The growth is really tremendous and all this has been possible due to contribution of each community member.

The idea of maintaining the list of FTO issue-seekers is a big success. We have been able to assign issues to nearly 50 contributors in the past 20 days. And, each day the list is growing and we are opening more and more FTO issues for helping new contributors in taking their first-step in Open Source with Public Lab.

Those community members who have shown some tremendous support for creating FTO issues and they really ensured that there is a check mark next to the name of each newcomer: @cess @gauravano @warren @lekhidugtal @Harshithpabbati @divyabaid16 @IshaGupta18 @anan12 @sashadev-sky @madeofhuman @HarshK @Divy123 @Rishabh570 @gautami_gg

Thank you everyone for the great work and cheers to this awesome community growth 🎉 🥂 💯

(The main image is a screenshot taken from GitHub Visualizer. To see the whole visualization, visit the link

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Providence, RI software development fellowship

by warren | 9 months ago | 0 | 3

Dates: April-May 2019

Location: Providence, RI

Compensation: $2,500-$4,500, based on experience and qualifications

Terms: Contract

The Public Laboratory for Open Technology and Science (Public Lab) is a community--supported by a 501(c)(3) non-profit--which develops and applies open-source tools to environmental exploration and investigation. By democratizing inexpensive and accessible Do-It-Yourself techniques, Public Lab creates a collaborative network of practitioners who actively re-imagine the human relationship with the environment.

Position Summary

We are looking for a code fellow to work in our Providence office for a term of 6-8 weeks (depending on hours) at approximately 20 hours per week to assist in the upgrading and expansion of the MapKnitter website, which assists communities in creating maps of environmental issues using aerial photos. The fellowship position will be part of a team of 6+ developers from around the world. is a Ruby on Rails website with:

Public Lab's open code community ( is a diverse, global group of contributors who are committed to respect and mutual support, and to code and community practices which support newcomers. Our goal is to develop and maintain software that supports environmental monitoring and online collaboration in the broader Public Lab community. Our Code of Conduct can be found at

Responsibilities will include:

  • Setup of a local development copy of the MapKnitter software
  • Installing and testing gem upgrades from
  • Helping to coordinate upgrades with project team members; cooperatively reading and reviewing code
  • Identifying and listing UI issues related to MapKnitter upgrades as the project develops
  • Assisting in Rails version upgrades
  • Designing and building tests for MapKnitter's automated test suite

For context, see our overall project plan:

Candidates should have experience with the following, although we can provide some support and training:

  • HTML/CSS and JavaScript
  • familiarity with Ruby on Rails
  • git/Github workflow

We also ask that candidates have:

  • The ability to balance multiple competing tasks and requests, and enjoyment from efficiently working toward goals and deadlines
  • A desire for and fulfillment from working on a team, but also an ability to work independently on job tasks
  • Incredible interpersonal skills, demonstrating great communication, kindness, respect, and patience within our collaborative work environment
  • An enjoyment of problem solving and the ability to put this to use in areas where project operations could be improved
  • Willingness to work remotely with some colleagues

Application process

Step 1: Please claim and complete one "first-timers-only" issue from the MapKnitter open source project: Our code welcoming program supports newcomers in making their first contribution, and you'll be compensated for your time with a $50 stipend upon completion. This compensation is only available for fellowship applicants from the Providence, RI area, and applicants will need to show that they have successfully installed the application on their computer.

Step 2: Upload your application materials to the following form by March 22. No phone calls please.

Application materials:

  • a paragraph describing your interest in the project
  • an example of non-Public Lab Rails application work (your own project or a contribution towards a project) on GitHub or a similar site
  • a link to your GitHub profile page or equivalent (GitLab, etc)
  • a link to the completed first-timers-only issue from Step 1

Public Lab is an equal opportunity employer committed to a diverse, multicultural work environment. We encourage people with different ability sets, people of color, and people of diverse sexual orientations, gender expressions and identities to apply.

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Call for Summer of Code 2019 proposals!

by warren | 10 months ago | 20 | 5

Outreachy and GSoC

We're part of two different summer fellowship programs this year, Outreachy and Google Summer of Code (#GSoC) -- both recruit software contributors to work on open source projects. We may also join Rails Girls Summer of Code (#RGSoC) once it opens, but would need to be accepted first.

We've done GSoC for a few years now, and are really excited to be part of RGSoC for a third year and Outreachy for a second season. Outreachy writes:

We expressly invite women (both cis and trans), trans men, and genderqueer people to apply. We also expressly invite applications from residents and nationals of the United States of any gender who are Black/African American, Hispanic/Latin@, Native American/American Indian, Alaska Native, Native Hawaiian, or Pacific Islander. Anyone who faces under-representation, systemic bias, or discrimination in the technology industry of their country is invited to apply.

So, we're asking students from both programs to start posting their proposals for comment, here. Read on!


Outreachy's application deadline is the March 26, 2019 at 4pm UTC. GSoC applications will be open between March 25, 2019 - April 9, 2019.

Read proposal ideas

Once you've gotten a bit familiar with our project (see our welcome page here), the first step is to look over our ideas page, which you can find here. These were collected from the brainstorm we did earlier in the year.

For Outreachy, we will be posting a project idea soon on the Outreachy website.

Please feel free to ask questions in the comments below, or to join our chat channel at https://publiclab/chat

Our welcoming page will help you understand how we collaborate, and we'll be there to help you take your first step. And try tackling a first-timers-only issue, to get an idea of how to become a contributor!

Also, read this page carefully to understand our workflow and how we structure summer of code projects:

Please ask questions! We're very friendly and we love welcoming new people into our community.

New this year

Once the term starts, we'll be asking all participants to review another person's work at least once time per week, and to either post a first-timers-only issue or help someone who's working on one once weekly. This will help us continue to support our growing community!

Post a proposal for comment

Once you've read through some of these ideas and become a bit more familiar with our projects, it's time to post a proposal of your own.

You don't need to have a complete or even concrete idea -- share your thoughts early and we'll help you refine your proposal, and help you choose something that's the right difficulty level as well as being something our project really needs.

We've created a template for you to post a proposal here. Click this button to begin:

Start drafting a proposal

Read other proposals

Before or after you post your own draft, read through others' listed below. Your best comments and input may come from other applicants!

Also see 2018's proposals here


Title Author Updated Likes Comments
GSoC proposal: Mapknitter Image Management and Synchronous Editing @divyabaid16 4 months ago 2
[withdrawn] GSoC Proposal: Mapknitter Overhaul @gauravano 8 months ago 1
SoC proposal: GSoC: Websocket Implementation for Real-time Usage and Sensor data and Display Library @namangupta 8 months ago 20
SoC proposal: Improving UI and Structure of Leaflet Environmental Layers @rkpattnaik780 8 months ago 5
SoC Proposal : Spectral Workbench Capture @sidntrivedi012 8 months ago 12
SOC 2019: A small proposal for global environmental monitoring @MaggPi 8 months ago 13
SoC proposal: MapKnitter Image Management & User Experience @govindjeevan7 8 months ago 4
GSOC-19 Mapknitter synchronous editing @vidit 8 months ago 2
SOC proposal: Extend Leaflet Environmental Layers with new layer menu and layer addition workflow @anan12 8 months ago 5
SoC proposal: Image Sequencer: Broadening Avenues @vibhordelgupta 8 months ago 2
MapKnitter Aerial Image labelling to detect Environmental issues using machine vision @sauvzi13397 8 months ago 5
GSoC proposal: Image Sequencer @aashnaaashna 8 months ago 10
GSoC proposal: Mapknitter Image Management and Synchronous Editing @igniteeng000 8 months ago 3
Outreachy Proposal 2019 For Public Lab: @gautami_gg 8 months ago 12
GSoC Proposal: Mapknitter Rails 6 upgrade @kaustubh_nair 8 months ago 7
GSoC proposal: Mapknitter Upgrade to Rails 6 @singhav 8 months ago 2
GSoC proposal: Mapknitter ORB Descriptor (w/ auto-stitching, pattern training, and live video support) and LDI revamp (major UI enhancements) @rexagod 8 months ago 35
SoC proposal: Community Toolbox overhaul @icode365 8 months ago 16
SoC proposal: Image Sequencer @lohithabhagam123 8 months ago 0
SoC proposal: Community-toolbox @jainsubhahu 8 months ago 10
SoC proposal: Image-Sequencer v3: Boosting the performance and adding demonstration based on colorimetry @lit2017001 8 months ago 7
Outreachy proposal: Extend Leaflet Environmental Layers with new layer menu and layer addition workflow @priya17081 8 months ago 12
GSoC proposal: Sensor data upload and display library @IshaGupta18 8 months ago 34
SoC proposal: Image Sequencer @f20171066 8 months ago 6
GSoC Proposal 2019: Mapknitter's Rails Upgrade @alaxallves 8 months ago 5
SoC proposal: PublicLab.Editor @f20171066 8 months ago 1
GSoC proposal: LEL 2.0 and work on Leaflet-Blurred projects . @sagarpreet 9 months ago 11
SoC proposal: Sensor data upload and display library @shakebameen 9 months ago 0
SoC proposal: Sensor data upload and display library @shakebameen 9 months ago 3
GSoC proposal: Automated feature detection and matching #300 @puneetbindal8989 9 months ago 2
SoC proposal: Enhancing the UI of publiclab and relevant changes to server @lekhidugtal 9 months ago 21
GSoC proposal: Automated feature detection and matching #300 @puneetbindal8989 9 months ago 0
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Leaflet.DistortableImage full resolution download

by warren | 10 months ago | 0 | 3

Across the Public Lab community, people are making their own maps using aerial photos (by balloon mapping, kite mapping, and the like) with the MapKnitter website - which helps people "stitch" or "knit" images into a combined map, using an existing satellite map base layer as a reference.

The core of MapKnitter's interface, the Leaflet.DistortableImage library, is seeing some new life as members of our coding community have started to dig in and make improvements! Its main goal of letting people distort aerial images to fit onto a map is being refined, debugged, and expanded. (This was made possible in part with support from NASA's AREN project)

Above, a new feature you can see in the menu is a full resolution download -- with no server-side processing at all. This was made possible through a lot of work by John905 and rexagod.

Try it out in the demo:

This takes the original full resolution image and distorts it in your browser (you may need to allow popups), and then downloads.

For example, the lead image generated this full-res distorted image: full.png (2304x1536 pixels)

See the preview below.

This may mean that for some smaller MapKnitter maps, you won't need to run a full export, which can take a while. This code should publish on MapKnitter within the next few days. Down the road, we're looking at more ways to refine the export process to make it even easier to make your own maps using balloon, kite, pole, or drone mapping.

image description

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RV SensorShip V

by cfastie | 11 months ago | 2 | 7

The original SensorShip had four environmental sensors and it was hard to cram all the wiring into the sailboat I printed for it. I was also concerned that a sailboat is not a ship. I also wanted a SensorShip with more sensors. So I searched Thingiverse for a more appropriate vessel.

Figure 1. An ESP8266 board and the bi- and trifurcating wiring harness for five I²C sensors (each sensor gets connected to the same four pins on the board). Plus three LEDs and a piezo buzzer. I’m going to need a bigger boat.

I quickly found Peter Sripol’s Utility Ship and the easier to print "make" of it by 08stanis. I immediately liked this ship because I had just reread Steinbeck’s The Log from the Sea of Cortez and the model reminded me of the Western Flyer.

Figure 2. The Western Flyer was built in 1937 and spent six weeks in 1940 in the Sea of Cortez with John Steinbeck and Ed Ricketts aboard. She had a long, hard life and was recently lifted off the harbor bottom and brought onto the hard.

Figure 3. The Western Flyer is being restored in Port Townsend, WA and will be used as a floating classroom and memorial to the poorly-formed ideas of Steinbeck and Ricketts about ecology and politics. Learn more here.

The new model is not really a ship, but it is a bigger boat and is designed to be easy to open to install stuff inside. It is intended for printing about two feet long, but it works well when printed 7.5 inches long.

Figure 4. The new RV SensorShip V is easy to print in 15 pieces and fun to glue together especially if assembling model boats is one of your favorite things to do. I used superglue.

Figure 5. The entire deck of RV SensorShip V can be used like a lid so it’s easy to install important stuff inside.

Figure 6. RV SensorShip V has five I²C sensors. Clockwise from upper left: BME280 (temperature, humidity, pressure), MLX90615 (thermal IR), VL53LOX (laser rangefinder), TSL2561 (light level), and MMA8451 (3 axis accelerometer). The paperclip on the left is for scale.

Figure 7. Two sensors are mounted on the stern deck of RV SensorShip V so they can be directed together at areas of interest. The laser rangefinder (right) and thermal IR (left) sensors are both directional.

Figure 8. Screen capture from the Blynk app of three hours of the data records from three of the five sensors on RV SensorShip V. The ship was next to my 3D printer when a 30-minute print was running. The laser rangefinder and thermal IR sensors were pointed toward the print head.

SensorShips incorporate ESP8266 microcontroller boards with integrated Wi-Fi. Data from the sensors are sent via Wi-Fi to the internet. This SensorShip sends its data to a Blynk server and the data can be viewed on a mobile device in real time.

A new feature of this SensorShip is the pair of directional sensors on the stern deck. I oriented the ship so these sensors were pointed near the print head while a short 3D print was made. Both of these sensors and also the accelerometer captured a clear record of when the 3D printer was operating (Figure 8).

This past weekend there were three days in a row with nighttime temperatures near 0°F. I have been heating my house with a woodstove this winter and was concerned that the cold snap might freeze pipes in the basement. I placed RV SensorShip V in the crawlspace where the most vulnerable pipes are. Fortunately we had some snow before the weekend, so I was able to bank the foundation with snow to provide some insulation.

Figure 9. I banked snow around the entire house before the cold weekend.

Figure 10. Temperature results from three different SensorShips for a week including a very cold weekend. RV SensorShip V (bottom) had its directional sensors pointed at the most vulnerable pipes in the crawlspace. The rangefinder was well positioned to detect raccoons. On Tuesday the 15th (dashed line) I surrendered and started using the oil furnace in addition to the woodstove. This figure is made from three screen captures from the Blynk app which were combined and annotated in Photoshop.

The basement low temperature dropped about one degree F for each of the cold nights finally dropping into the 30s F. I thought I had weathered the weather, but more cold nights were forecast, and in a few days the daytime high is forecast to be not much above 0°F. The woodstove would have a difficult time counteracting such temperatures, and provides almost no heat to the basement, so I ordered more heating oil for the furnace (which is in the basement).

I ran the furnace four times (Figure 10) in the first three days after the delivery (I had been out of oil since April). I learned that in order to raise the temperature on the first floor of the house into the 60s F, the temperature in the basement has to be warmed into the 50s F. That’s one reason I don’t like to use the furnace, but I think I will be very thankful for it over the next several days when the four-day average temperature will be very close to 0°F.

All three of the SensorShips use an ESP8266 board and connect to the internet via the integrated Wi-Fi. So SensorShips must remain in the range of my home Wi-Fi signal. I was pleased that RV SensorShip V had no problem connecting from the basement, even though the Wi-Fi router is on the second floor at the other end of the house.

All of the SensorShips are powered by 5V phone chargers plugged into the wall. They would last only a couple of days if powered by batteries because everything is powered continuously. I have not yet figured out how to sleep the ESP8266 boards or to use a low power external timer with them (my first attempt to use a timer failed). Let me know if you know a trick for using these boards with a TPL5110 timer.

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