American tech startup Scale has raised $18m in Series B funding led by Index Ventures to label data for AI application development from autonomous vehicles.

The funding round was joined by existing investors Accel and Y Combinator. Individual investors such as Dropbox CEO Drew Houston and entrepreneur Justin Kan also joined the round.

With the latest round, Scale has raised $22.7m in funding, including a $4.5m Series A in May last year led by Accel and Y Combinator.

After being established two years ago, the company has added leading companies in its clientele list, including Lyft, General Motors (Cruise), Zoox, Nuro, Voyage, nuTonomy and Embark.

Scale CEO and founder Alexandr Wang said: “Our Series B enables Scale to rapidly advance how human intelligence and machine learning can work together to make the once arduous and manual process of creating training data a breeze.

“As computers only learn from data that is fed to them, this makes Scale’s data-labelling accuracy, scalability, and speed important for its customers.”

“The success of AI-based applications is inherently dependent on the calibre of the data inputted, and we believe our human and machine integrated system provides customers with the precision needed to power AI applications.”

Scale receives raw, unlabelled data from a number of companies and processes them using a pool of human micro-tasking and machine learning, and returns it as scalable and accurate data sets.

Human-labelled data is vital for the machine-learning models that educate computers to see, a use case applied in autonomous cars.

As computers only learn from data that is fed to them, this makes Scale’s data-labelling accuracy, scalability, and speed important for its customers.

The Scale application programming interface (API) provides numerous human-labelling options such as semantic segmentation, image annotation, and sensor fusion.

So far, Scale has annotated more than 200,000 miles of data collected by self-driving cars.

In addition to driverless cars, Scale’s API for human intelligence is used to speed up work for companies’ development of robotics, drones, virtual assistants, and other solutions that heavily depend on AI.