Andrew Ng: Machine Learning in Robotics

Is it possible to offer it via simple api, useful by someone without knowledge in machine learning , where you give it data to train , and you get get a trained algorithm that can do perception stuff ?

hamner2• 15 years ago

The implementation of these algorithms is relatively straightforward. The challenge is the state of the art in computer vision is not currently at a point where it is possible to reliably detect 10s-100s of object categories in real time on current systems. It is currently possible to build systems that get decent real-time performance on detecting a few categories concurrently, or offline systems that get around 60% accuracy across hundreds of well-defined categories. Thus, (1) faster general purpose hardware, (2) better algorithms, or (3) running the best algorithms in ASICs designed for CV is necessary. The top labs now typically use GPU clusters to train / run their algorithms, with the computationally expensive stages usually being feature extraction and/or classifier training.

Google Predict (http://code.google.com/apis/predict/) offers a general machine learning API geared towards those who want to apply machine learning to their applications without subject-specific knowledge. I've not used it so I can't speak to its accuracy, but it is not geared towards computer vision and I imagine it would fail miserably at such tasks (since computer vision is highly dependent on domain-specific feature extraction techniques), and I imagine it performs well at NLP tasks. The primary limitation of such a system is that it acts as a black box - you throw data in and get answers out without any knowledge of the process behind it.

This black-box model is limiting for three major reasons. First, depending on the domain, incorporating domain-specific knowledge can greatly improve performance. Secondly, it is hard to understand the limitations of such a system. Many ML algorithms can fail catastrophically when the input is substantially different from the training data, and the black box makes it hard to understand when the system is likely to fail and adjust accordingly. Third, in many cases you face a tradeoff involving speed, memory, and classification/regression performance. This tradeoff is automatically determined for you and is not transparent.

I've been considering a general ML system that offers an API similar to Google Predict, yet is transparent in the feature extraction / model selection stages for those that would benefit from digging deeper into the system. Is this something that you would pay for?

Specifically for computer vision, there's a variety of startups and companies working on providing a system for object recognition and classification. One example is http://www.numenta.com/, though when I tried there software about a year ago it did not seem to function very well compared to the state of the art. Others that are making visual search type applications include http://www.tineye.com/ and http://www.kooaba.com

Andrew Ng: Machine Learning in Robotics

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