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Srikumar Sastry

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AAMAS Conference 2026 Conference Paper

DiffVAS: Diffusion-Guided Visual Active Search in Partially Observable Environments

  • Anindya Sarkar
  • Srikumar Sastry
  • Aleksis Pirinen
  • Nathan Jacobs
  • Yevgeniy Vorobeychik

Visualactivesearch(VAS)hasbeenintroducedasamodelingframework that leverages visual cues to direct aerial (e. g. , UAV-based) exploration and pinpoint areas of interest within extensive geospatialregions. PotentialapplicationsofVASincludedetectinghotspots for rare wildlife poaching, aiding search-and-rescue missions, and uncovering illegal trafficking of weapons, among other uses. Previous VAS approaches assume that the entire search space is known upfront, which is often unrealistic due to constraints such as a restricted field of view and high acquisition costs, and they typically learn policies tailored to specific target objects, which limits their ability to search for multiple target categories simultaneously. In this work, we propose DiffVAS, a target-conditioned policy that searches for diverse objects simultaneously according to task requirements in partially observable environments, which advances the deployment of visual active search policies in real-world applications. DiffVAS leverages a diffusion model to reconstruct the entire geospatial area from sequentially observed partial glimpses, which enables a target-conditioned reinforcement learning-based planning module to effectively reason and guide subsequent search steps. Extensive experiments demonstrate that DiffVAS excels in searching diverse objects in partially observable environments, significantly surpassing state-of-the-art methods on several datasets. Code and models are available at this link.

NeurIPS Conference 2024 Conference Paper

GOMAA-Geo: GOal Modality Agnostic Active Geo-localization

  • Anindya Sarkar
  • Srikumar Sastry
  • Aleksis Pirinen
  • Chongjie Zhang
  • Nathan Jacobs
  • Yevgeniy Vorobeychik

We consider the task of active geo-localization (AGL) in which an agent uses a sequence of visual cues observed during aerial navigation to find a target specified through multiple possible modalities. This could emulate a UAV involved in a search-and-rescue operation navigating through an area, observing a stream of aerial images as it goes. The AGL task is associated with two important challenges. Firstly, an agent must deal with a goal specification in one of multiple modalities (e. g. , through a natural language description) while the search cues are provided in other modalities (aerial imagery). The second challenge is limited localization time (e. g. , limited battery life, urgency) so that the goal must be localized as efficiently as possible, i. e. the agent must effectively leverage its sequentially observed aerial views when searching for the goal. To address these challenges, we propose GOMAA-Geo -- a goal modality agnostic active geo-localization agent -- for zero-shot generalization between different goal modalities. Our approach combines cross-modality contrastive learning to align representations across modalities with supervised foundation model pretraining and reinforcement learning to obtain highly effective navigation and localization policies. Through extensive evaluations, we show that GOMAA-Geo outperforms alternative learnable approaches and that it generalizes across datasets -- e. g. , to disaster-hit areas without seeing a single disaster scenario during training -- and goal modalities -- e. g. , to ground-level imagery or textual descriptions, despite only being trained with goals specified as aerial views. Our code is available at: https: //github. com/mvrl/GOMAA-Geo.

v2026.09.13