Have you ever wondered where people are located when they post on Twitter or take a digital photo? Eric Fischer, a programmer and designer, recently answered this question by creating a series of maps showing people’s location when they send a Twitter message or upload a photo to Flickr, the photo-sharing Web site.

The data visualization series is called “See something or say something,” and according to Mr. Fischer’s Twitter feed, uses Twitter and Flickr’s A.P.I., or application programming interface, to figure out the location and times of each photo or message. He then plots it on a map.

In the map images, Mr. Fischer chose orange dots to illustrate the location of photos uploaded to Flickr, the blue dots show Twitter messages and the white dots are the location of both services being used at the same time.

You can see from the map above, which shows a visualization of New York City, that Twitter messages are sent from all over the city, but the majority of photos are taken around Manhattan and in areas of the city that contain landmarks, including around the Statue of Liberty, and in the city’s parks..

Mr. Fischer said he uploaded 30 new images of cities to his Flickr feed on Wednesday, including fascinating data visualizations of Paris, London and Tokyo.

Correction: The color of Twitter circles are blue, not yellow.