Node-Adapt, Path-Adapt and Tree-Adapt:Model-Transfer Domain Adaptation for Random Forest

TL;DR

This paper introduces three novel domain adaptation methods for Random Forests that only require the source model and a few target samples, improving pedestrian detection accuracy in image-based object detection tasks.

Contribution

The paper presents Node-Adapt, Path-Adapt, and Tree-Adapt, three new RF-DA methods that do not need source data, only the trained source RF and target samples.

Findings

DA is effectively achieved with the proposed methods.

Methods outperform existing RF-DA approaches.

Applicable to pedestrian detection in images.

Abstract

Random Forest (RF) is a successful paradigm for learning classifiers due to its ability to learn from large feature spaces and seamlessly integrate multi-class classification, as well as the achieved accuracy and processing efficiency. However, as many other classifiers, RF requires domain adaptation (DA) provided that there is a mismatch between the training (source) and testing (target) domains which provokes classification degradation. Consequently, different RF-DA methods have been proposed, which not only require target-domain samples but revisiting the source-domain ones, too. As novelty, we propose three inherently different methods (Node-Adapt, Path-Adapt and Tree-Adapt) that only require the learned source-domain RF and a relatively few target-domain samples for DA, i.e. source-domain samples do not need to be available. To assess the performance of our proposals we focus on image-based object detection, using the pedestrian detection problem as challenging proof-of-concept. Moreover, we use the RF with expert nodes because it is a competitive patch-based pedestrian model. We test our Node-, Path- and Tree-Adapt methods in standard benchmarks, showing that DA is largely achieved.