The ACM Lifelog Search Challenge (LSC) is an annual comparative benchmarking exercise that brings together researchers in the field of multimedia retrieval to evaluate interactive search systems using a large-scale multimodal lifelog dataset. This paper presents an overview of the ninth edition of the challenge (LSC’26), held as a workshop during the ACM International Conference on Multimedia Retrieval (ICMR ’26) in Amsterdam. To broaden its scope, the workshop now features three submission tracks: the traditional Challenge Track for real-time search performance, a new General Lifelog Research Track for theoretical and architectural advancements, and an additional Open Source Track aimed at enhancing reproducibility and reducing barriers to entry for new participants.

For the eighth time since 2018, the ACM Lifelog Search Challenge (LSC) was run to compare interactive lifelog search systems in a live metrics-based challenge. The goal of the LSC workshop is to comparatively evaluate the capabilities of systems accessing a large multimodal lifelog. LSC'25 attracted eleven participating teams, each of which had developed an innovative interactive lifelog retrieval system. The benchmark was organised in a hybrid manner (due to political issues in 2025) at the LSC workshop at ACM ICMR'25 in Chicago, USA. This short paper summarises the LSC workshop setting and presents the participating lifelog search systems.

Most scholarly search services only provide basic text-matching or similarity-based searches, with limited operations that require manual configuration, such as sorting and filtering by specific metadata attributes. These capabilities are insufficient for researchers who often have queries that involve complex constraints and operations, such as ''enumerating the authors of a given paper along with the venues where they have published other papers.'' In this work, we develop an interactive and intuitive scholarly question answering system called NLQxform-UI, which allows users to pose complex queries in the form of natural language questions. It is capable of automatically translating these questions into SPARQL queries that can be executed over the DBLP knowledge graph to retrieve expected answers. Furthermore, the users can interact with each step of the answering process and browse the final results in a web-based interface. A video recording of our system is available at https://youtu.be/elq8CPykiyk Additionally, the system has been completely open-sourced: https://github.com/ruijie-wang-uzh/NLQxform-UI

Adding explanations to recommender systems is said to have multiple benefits, such as increasing user trust or system transparency. Previous work from other application areas suggests that specific user characteristics impact the users’ perception of the explanation. However, we rarely find this type of evaluation for recommender systems explanations. This paper addresses this gap by surveying 124 papers in which recommender systems explanations were evaluated in user studies. We analyzed their participant descriptions and study results where the impact of user characteristics on the explanation effects was measured. Our findings suggest that the results from the surveyed studies predominantly cover specific users who do not necessarily represent the users of recommender systems in the evaluation domain. This may seriously hamper the generalizability of any insights we may gain from current studies on explanations in recommender systems. We further find inconsistencies in the data reporting, which impacts the reproducibility of the reported results. Hence, we recommend actions to move toward a more inclusive and reproducible evaluation.

For the seventh time since 2018, the Lifelog Search Challenge (LSC) benchmarked interactive lifelog search systems in a live challenge. The LSC goal is to comparatively evaluate system capabilities to access large multimodal lifelogs comprising hundreds of thousands of records. LSC'24 attracted an unprecedented record number of twenty-one participating teams, where each team proposes innovative ideas implemented to new or already established interactive lifelog retrieval systems. The benchmark was organised in front of a live audience at the LSC workshop at ACM ICMR'24 in Phuket, Thailand. This short paper summarises the LSC workshop setting and presents the participating lifelog search systems.

The capture and subsequent analysis of egocentric imagery in the form of Lifelogs can be useful in several application areas. However, suitable hardware to record such data is not always available or can be cost-prohibitive. This paper introduced the OpenLifelogCam, an open-source hardware wearable camera platform that is designed to be customizable enough to cover a broad range of possible applications while being as cheap as possible to construct even in low volumes.

To support the replication of "MMSF: A Multimodal Sentiment-Fused Method to Recognize Video Speaking Style", which was presented at ICMR'23, this companion paper provides the details of the artifacts. Speaking style recognition is aimed at recognizing the styles of conversations, which provides a fine-grained description about talking. In the original paper, we proposed a novel multimodal sentiment-fused method, MMSF, which extracts and integrates visual, audio and textual features of videos and introduced sentiment in MMSF with cross-attention mechanism to enhance the video feature to recognize speaking styles. In this paper, we explain the details of the implement code and the dataset used for experiments.

For the sixth time since 2018, the Lifelog Search Challenge (LSC) was organized as a comparative benchmarking exercise for various interactive lifelog search systems. The goal of this international competition is to test system capabilities to access large multimodal lifelogs. LSC’23 attracted twelve participanting teams, each of whom had developed a competitive interactive lifelog retrieval system. The benchmark was organized in front of live audience at the LSC workshop at ACM ICMR’23. As in previous editions, this introductory paper presents the LSC workshop and introduces the participating lifelog search systems.

Interactive retrieval with user-friendly and performant interfaces remains a necessity for video retrieval, even in light of significant gains in retrieval performance through multi-modal encoders. In recent years, novel interaction modalities such as virtual reality (VR) and augmented reality (AR) have gained popularity, but the best way to adapt paradigms from traditional retrieval interfaces, especially for result browsing and interaction, remains an open research question. In this paper, we compare two video retrieval interfaces in a controlled setting to gain insight into the differences in video browsing between VR and desktop interfaces. We formulate hypotheses explaining why there might be performance differences between the two interfaces, define metrics to test the hypotheses, and show results based on data gathered at an evaluation campaign. Our results show that VR interfaces can be competitive in browsing performance and indicate that there can even be an advantage when browsing larger result sets in VR.

For the fifth time since 2018, the Lifelog Search Challenge (LSC) facilitated a benchmarking exercise to compare interactive search systems designed for multimodal lifelogs. LSC'22 attracted nine participating research groups who developed interactive lifelog retrieval systems enabling fast and effective access to lifelogs. The systems competed in front of a hybrid audience at the LSC workshop at ACM ICMR'22. This paper presents an introduction to the LSC workshop, the new (larger) dataset used in the competition, and introduces the participating lifelog search systems.

The Lifelog Search Challenge (LSC) is an annual benchmarking challenge for comparing approaches to interactive retrieval from multi-modal lifelogs. LSC'21, the fourth challenge, attracted sixteen participants, each of which had developed interactive retrieval systems for large multimodal lifelogs. These interactive retrieval systems participated in a comparative evaluation in front of an online live-audience at the LSC workshop at ACM ICMR'21. This overview presents the motivation for LSC'21, the lifelog dataset used in the competition, and the participating systems.

Gestures play an important role in our daily communications. However, recognizing and retrieving gestures in-the-wild is a challenging task which is not explored thoroughly in literature. In this paper, we explore the problem of identifying and retrieving gestures in a large-scale video dataset provided by the computer vision community and based on queries recorded in-the-wild. Our proposed pipeline, I3DEF, is based on the extraction of spatio-temporal features from intermediate layers of an I3D network, a state-of-the-art network for action recognition, and the fusion of the output of feature maps from RGB and optical flow input. The obtained embeddings are used to train a triplet network to capture the similarity between gestures. We further explore the effect of a person and body part masking step for improving both retrieval performance and recognition rate. Our experiments show the ability of I3DEF to recognize and retrieve gestures which are similar to the queries independently of the depth modality. This performance holds both for queries taken from the test data, and for queries using recordings from different people performing relevant gestures in a different setting.

In this work we analyze content statistics of the V3C1 dataset, which is the first partition of theVimeo Creative Commons Collection (V3C). The dataset has been designed to represent true web videos in the wild, with good visual quality and diverse content characteristics, and will serve as evaluation basis for the Video Browser Showdown 2019-2021 and TREC Video Retrieval (TRECVID) Ad-Hoc Video Search tasks 2019-2021. The dataset comes with a shot segmentation (around 1 million shots) for which we analyze content specifics and statistics. Our research shows that the content of V3C1 is very diverse, has no predominant characteristics and provides a low self-similarity. Thus it is very well suited for video retrieval evaluations as well as for participants of TRECVID AVS or the VBS.

The steady growth of multimedia collections - both in terms of size and heterogeneity - necessitates systems that are able to conjointly deal with several types of media as well as large volumes of data. This is especially true when it comes to satisfying a particular information need, i.e., retrieving a particular object of interest from a large collection. Nevertheless, existing multimedia management and retrieval systems are mostly organized in silos and treat different media types separately. Hence, they are limited when it comes to crossing these silos for accessing objects. In this paper, we present vitrivr, a general-purpose content-based multimedia retrieval stack. In addition to the keyword search provided by most media management systems, vitrivr also exploits the object's content in order to facilitate different types of similarity search. This can be done within and, most importantly, across different media types giving rise to new, interesting use cases. To the best of our knowledge, the full vitrivr stack is unique in that it seamlessly integrates support for four different types of media, namely images, audio, videos, and 3D models.

We present a tutorial focusing on video retrieval tasks, where state-of-the-art deep learning approaches still benefit from interactive decisions of users. The tutorial covers general introduction to the interactive video retrieval research area, state-of-the-art video retrieval systems, evaluation campaigns and recently observed results. Moreover, a significant part of the tutorial is dedicated to a practical exercise with three selected state-of-the-art systems in the form of an interactive video retrieval competition. Participants of this tutorial will gain a practical experience and also a general insight of the interactive video retrieval topic, which is a good start to focus their research on unsolved challenges in this area.

The IMOTION system is a multimodal content-based video search and browsing application offering a rich set of query modes on the basis of a broad range of different features. It is able to scale with the size of the collection due to its underlying flexible polystore called ADAMpro and its very effective retrieval engine Cineast, optimized for multi-feature fusion. IMOTION is simultaneously geared towards precision-focused searches, i.e., known-item search with image or text queries, and recall-focused, exploratory searches. In this demo, we will present the 2017 IMOTION system deployed on the IACC.3 collection consisting of 600 hours of Internet Archive video, which was also used in the TRECVID 2016 Ad-Hoc Video Search and in the 2017 Video Browser Showdown (VBS) challenge in which IMOTION ranked first. Conference attendees will have the chance to interact with the 2017 IMOTION system and quickly solve various retrieval tasks.