Measuring the world - Tools Demos

• Measuring the world - Tools Demos
  • Individual data capture
    • SCK
    • Images
    • Physical intervention
    • (B)arduino Sensor
    • GPS Mobile location
  • Collective data capture
    • Web Scrapping

Individual data capture

SCK

Images

Using motion detection technics or a simple timelapse you can get a lot of information on what's happening around you. A sequence of images can give you information on the number of persons, the color of cars, the size of dogs or any other subject of interest for your research.

Smart phone

Smart phones are filled with sensors, they can capture all kind of data and probably you will find a good quality camera. You should plan your capture periods, locations and frequency depending on what information you want to get from the images.

There is a lot of applications to record timelapses, TimeLapseCam is open source app that can record time lapses with the screen off. You can also use motion detection to only get images when something is happening there is a lot of apps that can detect motion and trigger the capture.

If images don't give you answers, you still can use your phone, try experimenting with Phyphox, it allows recording data from most of your phone sensors, export it, and even control the capture from a web browser.

Pi Camera

Using a Raspberry Pi SBC computer and a camera allow us to grab images in a simple and inexpensive way.

First install a Raspbian system on your sd card, you can follow this tutorial, be sure to reach the point where you enable and test the camera.

Now we can install a Web Interface to manage the camera, detect motion or record timelapses. You just need to follow the Installation Instructions until step 6.

If everything went OK when you open your computer browser and point to the Raspberry Pi IP address (eg http://172.16.23.21/html) you should see something like this:

You can check the usage documentation to configure your camera to save a timelapse or record videos when motion is detected.

Physical intervention

Plan a data collection interface using digital fabrications techniques from the Fab Lab, like so:

(B)arduino Sensor

Below there is an example of how you can use a simple sensor. However, you can use your B(arduino) if you like.

A photoresistor (also known as a light-dependent resistor, LDR, or photo-conductive cell) is a passive component that decreases resistance with respect to receiving luminosity (light) on the component's sensitive surface.

Example code that will output LDR value 20 times a second (20Hz) via USB Serial port.

int sensorPin = A0;
int sensorValue = 0;

void setup() {
  Serial.begin(115200);
}

void loop() {
  sensorValue = analogRead(sensorPin);
  Serial.println(sensorValue); 
  delay(50);
}

You can use the Arduino IDE Serial plotter to see the changes in real time:

To capture the data to a file for latter processing, in OSX and Linux you can do

stty -F /dev/ttyACM0 raw 115200
cat /dev/ttyACM0 > data.csv

Other option is installing this tool that allows you to capture directly to a CSV file and even include timestamps.

GPS Mobile location

Get GPS Logger for Android or similar app to save location data to a gpx file.

1. Select the file format in "recording details"

2. Send them to your laptop by simply sharing the file
3. You can then view your GPX files in a program like https://www.gpxsee.org/

Collective data capture

Web Scrapping