Day 12 (7/23/19): Bounding Classifiers

Today I experimented with different bounded classifiers for open set recognition. A bounding classifier essentially is a type of model which can detect out-of-distribution (OOD) samples, i.e. when presented with an image of a class it has not been trained on. In the image below, a bounded classifier would identify images found in the less dense regions as unknowns rather than try to fit them to a previously-learned class.

I performed my experiment evaluating different bounding classifiers by testing a Resnet50's accuracy in detecting out-of-distribution samples (original dataset is CUB200) either from generated Gaussian noise or the Oxford Flowers dataset. Here are two sample images from those respective dataloaders:

The results I achieved were very similar to those shown in this table (the third row is the CUB200 dataset):

Tomorrow I hope to finally begin to look into the intersection of incremental learning and open set recognition (having experiment with both aspects individually). Then, I will be able to formulate a better idea of the kinds of results I can expect to see for my project.

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Day 9 (7/18/19): Incrementally Learning CUB200

Today I continued my work learning about incremental learning models by testing out different strategies on the CUB200 dataset. From what I understand from reading various articles, there seem to be five different approaches to mitigating catastrophic forgetting in lifelong learning models. These are regularization methods (adding constraints to a network's weights), ensemble methods (train multiple classifiers and combine them), rehearsal methods (mix old data with data from the current session), dual-memory methods (based off the human brain, includes a fast learner and a slow learner), and sparse-coding methods (reducing the interference with previously learned representations). All of these methods have their constraints and I don't believe it is yet clear what method (or what combination of different methods) is best. Full rehearsal obviously seems to be the most effective at making the model remember what it had previously learned but given that all training exam...

Day 30 (8/16/19): Final Presentations

Today we gave our final presentations, and everyone did a great job. I would like to thank everyone who helped me with this amazing experience! I'm very thankful to have had the opportunity to work on such interesting research with such amazing people this summer.

Day 24 (8/8/19): Multilayer Perceptron Experiment

I continued gathering more results for my presentation today, and the data table is coming along nicely. We are able to see a significant trend that using Mahalanobis instead of Baseline Thresholding recovers much of the OOD recognition that is lost with streaming or incremental models. The SLDA model appears to be a lightweight, accurate streaming model which can be paired with Mahalanobis to be useful as an embedded agent in the real world. For the purposes of demonstrating catastrophic forgetting, I ran five experiments and averaged the results for a simple incrementally trained MLP. Obviously, the model failed miserably and was achieving only about 1% of the accuracy of the offline model. Including this is only to show how other forms of streaming and incremental models are necessary to develop lifelong learning agents. A diagram of a simple multilayer perceptron.

RIT CIS Summer Internship

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