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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Overview of ImageCLEFlifelog 2019: Solve My Life Puzzle and Lifelog Moment Retrieval</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Duc-Tien Dang-Nguyen</string-name>
          <xref ref-type="aff" rid="aff4">4</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Luca Piras</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Michael Riegler</string-name>
          <xref ref-type="aff" rid="aff3">3</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Liting Zhou</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Mathias Lux</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Minh-Triet Tran</string-name>
          <xref ref-type="aff" rid="aff5">5</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Tu-Khiem Le</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Van-Tu Ninh</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Cathal Gurrin</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Dublin City University</institution>
          ,
          <addr-line>Dublin</addr-line>
          ,
          <country country="IE">Ireland</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>ITEC, Klagenfurt University</institution>
          ,
          <addr-line>Klagenfurt</addr-line>
          ,
          <country country="AT">Austria</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Pluribus One &amp; University of Cagliari</institution>
          ,
          <addr-line>Cagliari</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff3">
          <label>3</label>
          <institution>Simula Metropolitan Center for Digital Engineering</institution>
          ,
          <addr-line>Oslo</addr-line>
          ,
          <country country="NO">Norway</country>
        </aff>
        <aff id="aff4">
          <label>4</label>
          <institution>University of Bergen</institution>
          ,
          <addr-line>Bergen</addr-line>
          ,
          <country country="NO">Norway</country>
        </aff>
        <aff id="aff5">
          <label>5</label>
          <institution>University of Science</institution>
          ,
          <addr-line>VNU-HCM, Ho Chi Minh City</addr-line>
          ,
          <country country="VN">Vietnam</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>This paper describes ImageCLEFlifelog 2019, the third edition of the Lifelog task. In this edition, the task was composed of two subtasks (challenges): the Lifelog Moments Retrieval (LMRT) challenge that followed the same format as in the previous edition, and the Solve My Life Puzzle (Puzzle), a brand new task that focused on rearranging lifelog moments in temporal order. ImageCLEFlifelog 2019 received noticeably higher submissions than the previous editions, with ten teams participating resulting in a total number of 109 runs.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        Since 2016 with the rst lifelog initiative, the NTCIR-12 - Lifelog task [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ],
research in lifelogging, `a form of pervasive computing, consisting of a
unied digital record of the totality of an individual's experiences, captured
multimodally through digital sensors and stored permanently as a personal multimedia
archive' [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ], is getting more attention, especially within the multimedia
information retrieval community. However, given the huge volume of data that a lifelog
would generate, along with the complex patterns of the data, we are just at the
starting point of lifelog data organisation. We need to advance the next step of
development and to unlock the potential of such data. There is a need new ways
of organising, annotating, indexing and interacting with lifelog data, and that is
the key motivation of the Lifelog task at ImageCLEF.
      </p>
      <p>
        The ImageCLEFlifeLog2019 task at ImageCLEF 2019 [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ], was the third
edition of the task, with previous editions in 2017 [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] and 2018 [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ], which were
inspired by the fundamental image annotation and retrieval tasks of ImageCLEF
since 2003. This year, the task continued to follow the general evolution of
ImageCLEF, by applying the advanced deep learning methods and extending the focus
to multi-modal approaches instead of only working just with image retrieval.
      </p>
      <p>Comparing to the previous editions, in this third edition we merged the
previous two sub-tasks (challenges): Activities of Daily Living understanding
(ADLT) and Lifelog Moment Retrieval (LMRT) into a single challenge (LMRT)
and proposed a brand new one: Solve My Life Puzzle (Puzzle), which focused
on the new ways of organising lifelog data, in particular in rearranging lifelog
moments.</p>
      <p>The details of this year two challenges will be provided in section 2. This
includes also the descriptions of data and resources. For the rest of the paper, in
Section 3, submissions and results are presented and discussed and in the nal
section 4 the paper is concluded and nal remarks and future work are discussed.
2
2.1</p>
    </sec>
    <sec id="sec-2">
      <title>Overview of the Task</title>
      <sec id="sec-2-1">
        <title>Motivation and Objectives</title>
        <p>An increasingly wide range of personal devices, such as smartphones, video
cameras as well as wearable devices that allow capturing pictures, videos, and audio
clips for every moment of our lives are becoming available. Considering the huge
volume of data created, there is a need for systems that can automatically
analyse the data in order to categorize, summarize and also query to retrieve the
information the user may need.</p>
        <p>
          Despite the increasing number of successful related workshops and panels,
lifelogging has seldom been the subject of a rigorous comparative benchmarking
exercise as, for example, the new lifelog evaluation task at NTCIR-13 [
          <xref ref-type="bibr" rid="ref8">8</xref>
          ] or the
last editions of the ImageCLEFlifelog task [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ][
          <xref ref-type="bibr" rid="ref3">3</xref>
          ]. In this edition we aimed to
bring the attention of lifelogging to a wide audience and to promote research
into some of the key challenges of the coming years.
2.2
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>Challenge Description</title>
      </sec>
      <sec id="sec-2-3">
        <title>Lifelog Moment Retrieval Task (LMRT)</title>
        <p>In this task, the participants are required to retrieve a number of speci c
moments in a lifeloggers life. Moments are de ned as semantic events, or activities
that happened throughout the day. For example, a participant would have been
required to nd and return relevant moments for the query \Find the moment(s)
when the user1 is cooking in the kitchen". In this edition, particular attention
was to be paid to the diversi cation of the selected moments with respect to the
target scenario. The ground truth for this subtask was created using a manual
annotation process. Figure 1 illustrates some examples of the moments when the
lifelogger was having co ee with friends". In addition, listings 1 and 2 list all the
queries used in the challenge.</p>
        <sec id="sec-2-3-1">
          <title>Description: Find the moment when u1 was eating an icecream beside the sea</title>
        </sec>
        <sec id="sec-2-3-2">
          <title>Narrative: To be relevant, the moment must show both the ice cream with cone in the hand of u1 as well as the sea clearly visible. Any moments by the sea, or eating an ice cream which do not occur together are not considered to be relevant.</title>
          <p>T.002 Having Food in a Restaurant</p>
        </sec>
        <sec id="sec-2-3-3">
          <title>Description: Find the moment when u1 was eating food or drinkingU1 was eating</title>
          <p>food in a restaurant while away from home. Any kinds of dishes are relevant. Only</p>
        </sec>
        <sec id="sec-2-3-4">
          <title>Drinking co ee and have dessert in a cafe won't be relevant.</title>
          <p>T.003 Watching Videos</p>
        </sec>
        <sec id="sec-2-3-5">
          <title>Description: Find the moment when u1 was watching video when using other digital devices.</title>
        </sec>
        <sec id="sec-2-3-6">
          <title>Narrative: To be relevant, u1 must be watching videos in any location and any digital devices can be considered. For example: TV machine, tablet, mobile phone, laptop, desktop computer.</title>
          <p>T.004 Photograph of a Bridge</p>
        </sec>
        <sec id="sec-2-3-7">
          <title>Description: Find the moment when u1 was taking a photo of a bridge.</title>
        </sec>
        <sec id="sec-2-3-8">
          <title>Narrative: U1 was walking on a pedestrian street and stopped to take a photo of a bridge. Moments when u1 was walking on a street without stopping to take a photo of a bridge are not relevant. Any other moment showing a bridge when a photo was not being taken are also not considered to be relevant.</title>
          <p>T.005 Grocery Shopping</p>
        </sec>
        <sec id="sec-2-3-9">
          <title>Description: Find the moment when u1 was shopping for food in a grocery shop.</title>
        </sec>
        <sec id="sec-2-3-10">
          <title>Narrative: To be considered relevant, u1 must be clearly in a grocery shop and bought something from the it.</title>
          <p>T.006 Playing a Guitar</p>
        </sec>
        <sec id="sec-2-3-11">
          <title>Description: Find the moment when U1 or a man is playing guitar in view.</title>
        </sec>
        <sec id="sec-2-3-12">
          <title>Narrative:Any use of guitars indoors could be considered relevant. Any type of</title>
        </sec>
        <sec id="sec-2-3-13">
          <title>Guitar could be considered as relevant.</title>
          <p>T.007 Cooking</p>
        </sec>
        <sec id="sec-2-3-14">
          <title>Description: Find moments when u1 was cooking food.</title>
        </sec>
        <sec id="sec-2-3-15">
          <title>Narrative:The moments shows U1 was cooking food at any places are relevant.</title>
          <p>T.008 Car Sales Showroom</p>
        </sec>
        <sec id="sec-2-3-16">
          <title>Description: Find the moments when u1 was in a car sales showroom.</title>
        </sec>
        <sec id="sec-2-3-17">
          <title>Narrative: u1 visited a car sales showroom a few times. Relevant moments show u1 indoors in a car sales showroom, either looking at cars or waiting for a salesman sitting at a table. Any moments looking at cars while outside of a showroom are not considered relevant.</title>
          <p>T.009 Public Transportation</p>
        </sec>
        <sec id="sec-2-3-18">
          <title>Description: Find the moments when U1 is taking the public transportation in any countries.</title>
        </sec>
        <sec id="sec-2-3-19">
          <title>Narrative: To be considered relevant,the U1 must take a public transportation to other place. The moments that the U1 is driving a car is not relevant.</title>
          <p>T.010 Paper or Book Reviewing</p>
        </sec>
        <sec id="sec-2-3-20">
          <title>Description: Find all moments when u1 was reading a paper or book.</title>
        </sec>
        <sec id="sec-2-3-21">
          <title>Narrative: To be relevant, the paper or book must be visible in front of U1 and sometimes U1 use a pen to mark on the paper or book.</title>
          <p>Listing 1: Description of topics for the development set in LMRT.</p>
        </sec>
        <sec id="sec-2-3-22">
          <title>Description: Find the moment when u1 was looking at items in a toyshop.</title>
        </sec>
        <sec id="sec-2-3-23">
          <title>Narrative: To be considered relevant, u1 must be clearly in a toyshop. Various toys are being examined, such as electronic trains, model kits and board games. Being in an electronics store, or a supermarket, are not considered to be relevant.</title>
          <p>T.002 Driving home</p>
        </sec>
        <sec id="sec-2-3-24">
          <title>Description: Find any moment when u1 was driving home from the o ce.</title>
        </sec>
        <sec id="sec-2-3-25">
          <title>Narrative: Moments which show u1 is driving home from the o ce is relevant.</title>
        </sec>
        <sec id="sec-2-3-26">
          <title>Driving from other place and to other place are not relevant.</title>
          <p>T.003 Seeking Food in a Fridge</p>
        </sec>
        <sec id="sec-2-3-27">
          <title>Description: Find the moments when u1 was looking inside a refrigerator at home.</title>
        </sec>
        <sec id="sec-2-3-28">
          <title>Narrative: Moments when u1 is at home and looking inside a refrigerator are considered relevant. Moments when eating food or cooking in the kitchen are not considered relevant.</title>
          <p>T.004 Watching Football</p>
        </sec>
        <sec id="sec-2-3-29">
          <title>Description: Find the moments when either u1 or u2 was watching football on the TV.</title>
        </sec>
        <sec id="sec-2-3-30">
          <title>Narrative: To be considered relevant, either u1 or u2 must be indoors and watching football on a television. Watching any other TV content is not considered relevant.</title>
          <p>T.005 Co ee Time</p>
        </sec>
        <sec id="sec-2-3-31">
          <title>Description: Find the moment when u1 was having co ee in a cafe.</title>
        </sec>
        <sec id="sec-2-3-32">
          <title>Narrative:To be considered relevant, u1 must be in a cafe and having co ee alone or with another individual.</title>
          <p>T.006 Having Breakfast at Home</p>
        </sec>
        <sec id="sec-2-3-33">
          <title>Description:U1 was having breakfast at home and the breakfast time must be from 5:00 am until 9:00 am</title>
        </sec>
        <sec id="sec-2-3-34">
          <title>Narrative: To be considered relevant, the moments must show some parts of the furniture being assembled.</title>
          <p>T.007 Having Co ee with Two Persons</p>
        </sec>
        <sec id="sec-2-3-35">
          <title>Description: Find the moment when u1 was having co ee with two person.</title>
        </sec>
        <sec id="sec-2-3-36">
          <title>Narrative: Find the moment when u1 was having co ee with two person. One was wearing blue shirt and the other one was wearing white cloth. Gender is not relevant.</title>
          <p>T.008 Using a Smartphone Outside</p>
        </sec>
        <sec id="sec-2-3-37">
          <title>Description: Find the moment when u1 was using smartphone when he was walking or standing outside.</title>
        </sec>
        <sec id="sec-2-3-38">
          <title>Narrative: To be considered relevant, u1 must be clearly using a smartphone and the location is outside.</title>
          <p>T.009 Wearing a Red Plaid Shirt</p>
        </sec>
        <sec id="sec-2-3-39">
          <title>Description: Find the moment when U1 was wearing a red plaid shirt.</title>
        </sec>
        <sec id="sec-2-3-40">
          <title>Narrative: To be relevant, the user1 was wearing a red plaid shirt in a day life.</title>
          <p>T.010 Having a Meeting in China</p>
        </sec>
        <sec id="sec-2-3-41">
          <title>Description: Find all moments when u1 was attending a meeting in China.</title>
        </sec>
        <sec id="sec-2-3-42">
          <title>Narrative: To be relevant, the user1 must be in China and was having a meeting with others.</title>
          <p>Listing 2: Description of topics for the test set in LMRT.</p>
        </sec>
      </sec>
      <sec id="sec-2-4">
        <title>Solve my Life Puzzle Task (Puzzle)</title>
        <p>Given a set of lifelog images with associated metadata (e.g., biometrics, location,
etc.), but no timestamps, the participants needed to analyse these images and
rearrange them in chronological order and predict the correct day (e.g. Monday
or Sunday) and part of the day (e.g. morning, afternoon, or evening). Figure 2
illustrates an example of this challenge.
2.3</p>
      </sec>
      <sec id="sec-2-5">
        <title>Dataset</title>
        <p>
          The data was a medium-sized collection of multimodal lifelog data over 42 days
by two lifeloggers. The contribution of this dataset over previously released
datasets was the inclusion of additional biometric data, a manual diet log and
the inclusion of conventional photos. In most cases the activities of the lifeloggers
were separate and they did not meet. However on a small number of occasions
the lifeloggers appeared in data of each other. The data consists of:
{ Multimedia Content. Wearable camera images captured at a rate of about
two images per minute and worn from breakfast to sleep. Accompanying this
image data was a time-stamped record of music listening activities sourced
from Last.FM1 and an archive of all conventional (active-capture) digital
photos taken by the lifelogger.
{ Biometrics Data. Using the FitBit tness trackers2, the lifeloggers
gathered 24 7 heart rate, calorie burn and steps. In addition, continuous blood
glucose monitoring captured readings every 15 minutes using the Freestyle
Libre wearable sensor3.
1 Last.FM Music Tracker and Recommender - https://www.last.fm/
2 Fitbit Fitness Tracker (FitBit Versa) - https://www. tbit.com
3 Freestyle Libre wearable glucose monitor - https://www.freestylelibre.ie/
(a) Evening-Monday
(b) Morning-Tuesday
(d) Afternoon-Wednesday
(e) Morning-Thursday
(f) Afternoon-Friday
(g) Afternoon-Saturday
(h) Morning-Sunday
(i) Afternoon-Sunday
{ Human Activity Data. The daily activities of the lifeloggers were captured
in terms of the semantic locations visited, physical activities (e.g. walking,
running, standing) from the Moves app4, along with a time-stamped diet-log
of all food and drink consumed.
{ Enhancements to the Data. The wearable camera images were annotated
with the outputs of a visual concept detector, which provided three types of
outputs (Attributes, Categories and Concepts). Two visual concepts which
include attributes and categories of the place in the image are extracted
using PlacesCNN [18]. The remaining one is detected object category and
its bounding box extracted by using Faster R-CNN [
          <xref ref-type="bibr" rid="ref14">14</xref>
          ] trained on MSCOCO
dataset [
          <xref ref-type="bibr" rid="ref12">12</xref>
          ].
        </p>
        <p>Format of the metadata. The metadata was stored in a .csv les, which
was called the minute-based table. The precise structured of it is described in
Table 2. Additionally, extra metadata was included, such as visual categories
and concepts descriptors. The format of the extra metadata could be found in
Table 3.
4 Moves App for Android and iOS - http://www.moves-app.com/
LMRT For assessing performance, classic metrics were deployed. These metrics
were:
{ Cluster Recall at X (CR@X) - a metric that assesses how many di erent
clusters from the ground truth are represented among the top X results;
{ Precision at X (P@X) - measures the number of relevant photos among the
top X results;
{ F1-measure at X (F1@X) - the harmonic mean of the previous two.</p>
        <p>Various cut o points were considered, e.g., X=5, 10, 20, 30, 40, 50. O
cial ranking metrics were the F1-measure@10, which gives equal importance to
diversity (via CR@10) and relevance (via P@10).</p>
        <p>Participants were allowed to undertake the sub-tasks in an interactive or
automatic manner. For interactive submissions, a maximum of ve minutes of
search time was allowed per topic. In particular, methods that allowed interaction
with real users (via Relevance Feedback (RF), for example), i.e., beside of the
best performance, the way of interaction (like number of iterations using RF),
or innovation level of the method (for example, new way to interact with real
users) were encouraged.</p>
        <p>Puzzle For the Puzzle task, we used Kendall's Tau score to measure the
similarity of the temporal order between the participant's temporal arrangement
and ground-truth for each query. The formula of Kendall's Tau is as follows:
= max 0;</p>
        <p>C D
C + D
(1)
where C and D are the number of concordant pairs and discordant pairs
correspondingly between the participant's submission order and the one of
groundtruth. In the original Kendall's Tau formula, the range of the formula is from
[ 1; 1], however, we choose to narrow the range of the score to [0; 1]. It means that
if the number of opposite ranking-direction pairs are greater than the quantity
of the same ranking-direction pairs, participants would get nothing in Kendall's
Tau score. The accuracy of part-of-day prediction was computed simply by
dividing the number of correct predictions by the total number of predictions.
time zone</p>
        <sec id="sec-2-5-1">
          <title>The name of volunteers timezone</title>
        </sec>
        <sec id="sec-2-5-2">
          <title>Europe/Dublin</title>
          <p>Field name
minute ID
utc time
local time
lat
lon
name
song
steps
calories
historic glucose
(mmol/L)
scan glucose
(mmol/L)
heart rate
distance
img00 id to
img 19 id
cam00 id to
cam14 id
Finally, the primary score was computed as the average of Kendall's Tau score
and accuracy of part-of-day prediction for all queries.
2.5</p>
        </sec>
      </sec>
      <sec id="sec-2-6">
        <title>Ground Truth Format</title>
        <p>LMRT Task. The ground truth for the LMRT task was provided in two
individual txt les: one le for the cluster ground truth and one le for the
relevant image ground truth.</p>
        <p>In the cluster ground-truth le, each line corresponded to a cluster where the
rst value was the topic id, followed by cluster id number, followed by the cluster
user tag separated by comma. Lines were separated by an end-of-line character
(carriage return). An example is presented below:
{ 1, 1, Icecream by the Sea
{ 2, 1, DCU canteen
{ ...
{ 2, 8, Restaurant 5
{ 2, 9, Restaurant 6
{ ...</p>
        <p>In the relevant ground-truth le, the rst value on each line was the topic
id, followed by a unique photo id, and then followed by the cluster id number
(that corresponded to the values in the cluster ground-truth le) separated by
comma. Each line corresponded to the ground truth of one image and lines were
separated by an end-of-line character (carriage return). An example is presented
below:
{ 1, u1 20180528 1816 i00, 1
{ 1, u1 20180528 1816 i02, 1
{ 1, u1 20180528 1816 i01, 1
{ 1, u1 20180528 1817 i01, 1
{ 1, u1 20180528 1817 i00, 1
{ 1, u1 20180528 1818 i02, 1
{ ...
{ 2, u1 20180508 1110 i00, 1
{ 2, u1 20180508 1110 i01, 1
{ 2, u1 20180508 1111 i00, 1
{ 2, u1 20180508 1111 i01, 1
{ 2, u1 20180508 1112 i01, 1
{ ...</p>
        <p>Puzzle Task The ground truth was provided in only one individual .csv
le. For each line in this le, rst value was the id of the query, followed by
the id of image provided by the organisers, followed by the order that the image
should be arranged in this query in temporal manner, followed by the part-of-day
prediction. Values in each line were separated by comma. Lines were separated by
and end-of-line character (carriage return). The values in ground-truth le were
sorted by query id, and then image id column in ascending order. An example
is shown below:
{ 1, 001.JPG, 17, 1
{ 1, 002.JPG, 8, 1
{ 1, 003.JPG, 9, 1
{ 1, 004.JPG, 1, 1
{ 1, 005.JPG, 2, 1
{ ...
{ 8, 001.JPG, 12, 3
{ 8, 002.JPG, 16, 3
{ 8, 003.JPG, 13, 3
{ 8, 004.JPG, 15, 3
{ 8, 005.JPG, 10, 1
{ ...</p>
        <p>
          Run
Organiser [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ] RUN1*
        </p>
        <p>
          RUN2*
ATS [
          <xref ref-type="bibr" rid="ref17">17</xref>
          ] RUN1
        </p>
        <p>RUN2
RUN3
RUN4
RUN5
RUN6
RUN7
RUN8
RUN9
RUN11</p>
        <p>
          RUN12
BIDAL [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] RUN1
        </p>
        <p>RUN2</p>
        <p>
          RUN3
HCMUS [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ] RUN1
        </p>
        <p>
          RUN2
REGIM [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ] RUN1
        </p>
        <p>RUN2
RUN3
RUN4
RUN5
RUN6
Notes: * submissions from the organizer teams are just for reference.</p>
        <p>y submissions submitted after the o cial competition.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3 Evaluation Results</title>
      <p>3.1</p>
      <sec id="sec-3-1">
        <title>Participating Groups and Runs Submitted</title>
        <p>This year the number of participants as well as the number of submissions was
considerably higher with respect to 2018: we received in total 50 valid
submissions (46 o cial and 4 additional) for LMRT, and 21 (all are o cial) for Puzzle,
from 10 teams representing over 10 countries. The submitted runs and their
results are summarised in Tables 4 and 5.
3.2</p>
      </sec>
      <sec id="sec-3-2">
        <title>Results</title>
        <p>In this section we provide a short description of all submitted approaches followed
by the o cial result of the task.</p>
        <p>
          The Organiser team [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ] provided a baseline approach to the LMRT task
with a web-based interactive search engine called LIFER 2.0, which was based
on a previous system [19] used at the LSC 2018 Lifelog Search Challenge. The
authors submitted two runs which were obtained by letting two novice users
perform interactive moment retrieval on the search engine for all ten queries. For
the Puzzle task, the team proposed an activity mining approach which utilised
Bag-of-Visual-Words (BOVW) methods. For each image in a query, the authors
nd the most relevant images in the training data based on the L2 distance of
BOVW vectors to predict the part-of-day and chronological index of the images.
        </p>
        <p>
          Team
Organiser [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ]
        </p>
        <p>Notes: * submissions from the organizer teams are just for reference.</p>
        <p>
          The REGIM-Lab [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ] focused on LMRT task by improving the system from
their last year participation with NoSQL which o ers distributed database and
framework to handle huge data. They employed the ground-truth of development
set to improve the ne-tuning phase for concept extraction. In addition, CQL
Query was used to exploit complicated metadata. For the query analysis, the
authors trained a LSTM classi er to enhance the query with relevant concepts.
        </p>
        <p>
          The UPB team [
          <xref ref-type="bibr" rid="ref6">6</xref>
          ] proposed the algorithm to eliminate blurry images which
contain less information using a blur detection system. Following that, a
metadata restriction lter, which was created manually by users, was applied to the
dataset to further remove uninformative images. The remaining images was then
computed a relevance score based on given metadata description for query
answering.
        </p>
        <p>
          The UAPTBioinformatics (UAPT) team [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ] proposed an automatic
approach for LMRT task. The images are pre-processed through an automatic
selection step to eliminate images with irrelevant information to the topics
(feature extraction, machine learning algorithm, k-nearest neighbors, etc.) and more
visual concepts were generated using various state-of-the-art models (Google
Cloud Vision API, YOLOv3). Then they extracted relevant words from topics'
titles and narratives, dividing them into ve categories, and nally matching
them with the annotation concepts of lifelog images using a word embedding
model trained on Google News dataset. Moreover, an extra step to reuse
unselected images from the pre-processing steps for image similarity matching was
proposed to increase the performance of their system.
        </p>
        <p>
          The TUC MI team [
          <xref ref-type="bibr" rid="ref16">16</xref>
          ] proposed an automatic approach for LMRT task.
They rstly extracted twelve types of concept from di erent pre-trained models
to increase the annotation information for lifelog data (1191 labels in total).
For image processing, two methods were introduced to transform images into
vectors: image-based vectors and segment-based vectors. For query processing,
they processed the query with Natural Language Processing techniques and
introduced a token vector which has the same dimension as image/segment vector.
Finally, they de ned a formula to compare the similarity between image/segment
and token vector and conducted an ablation study to nd the best model that
achieved the highest score in this task.
        </p>
        <p>
          The HCMUS team [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ] proposed to extract semantic concepts from images
to adapt to lifelogger's habits and behaviours in daily life. They rstly identi ed
a list of concepts manually, then trained object detectors to extract extra visual
concepts automatically. Moreover, they also utilised object' region of interest
to infer its color by K-Means clustering. To further understand the temporal
relationship between events, they also integrated the visualization function for
an event sequence in their retrieval system. For the Puzzle task, the HCMUS
team [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ] utilised a BOVW approach to retrieve the visually similar moments
with reference to lifelog data to infer the probability of the time and order of the
images. Before applying the proposed remedy, they tried to cluster the images
into groups based on the provided concepts extracted from PlacesCNN, GPS
location, and user activities.
        </p>
        <p>
          The BIDAL team [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] participated in both Puzzle and LMRT tasks. For the
LMRT task, they introduced their interactive system with two main stages. For
stage 1, they generated many atomic clusters from the dataset based on rough
concepts and utilising text annotation to create Bag-of-Words (BOW) vectors
for each image. In stage 2, they generated the BOW vector for query texts and
found similar images that suited the context and content of the query. They then
used the output for result expansion by adding more images which were in the
same cluster. Finally, an end-user chooses appropriate images for the query. For
the Puzzle task, they proposed to use visual feature matching via two similarity
functions between each image in both train data and test data as the initial step
to lter out dissimilarity associative pairs (train-test image pairs). Finally, the
remaining images are grouped based on temporal order of train data so that it
forms the full set as test data to rearrange the images.
        </p>
        <p>The ZJUTCVR team [20] pre-processed the images with blur/cover lters
to eliminate the blurred and occluded images. Then, they proposed three
approaches to handle the remaining lifelog images: the two-class approach, the
eleven-class approach, and the clustering approach. For two-class approach, the
authors divided query topics into directories and ran a test on each directory
with a ne-tuned CNN. After that, the results are classi ed into two classes
based on the relevance to topic description. The eleven-class approach shared
the same process with the previous method, but the results are split into 11
classes, where 10 classes are corresponding to 10 query topics and the 11th class
contains irrelevant images to all 10 topics. With the clustering approach, the
team inherited the procedure of two-class approach with a modi cation after
the rst-round retrieval by clustering images with LVQ algorithm.</p>
        <p>
          The ATS team [
          <xref ref-type="bibr" rid="ref17">17</xref>
          ] approached the LMRT task with 11 automatics runs and
1 interactive run. All automatic runs shared the same process with 4
components: Interpretation, Subset selection, Scoring and Re nement, but di ered in
the con guration of selecting the approach of each component. The
interpretation state provided keywords and synonyms approaches which utilised WordNet
and Word2Vec to diversify the results. The choice of subset is highly reliant on
the con guration to use partial match or entire dataset to test. A scoring
process was used to produce nal ranking with three settings: label counting, topic
similarity and SVM. The Re nement step o ered multiple approaches:
weighting, thresholding, visual clustering and temporal clustering. Finally, the team
conducted ablation study to nd the best con guration. The interactive run was
done by letting user lter the subset of dataset and choose automatic approach
of each component to complete the query.
        </p>
        <p>
          The o cial results are summarised in Tables 4 and 5. For LMRT (Table 4),
eight teams participated and the highest F1@10 was submitted by HCMUS [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ]
at their second run (RUN2) with a score of 0:61 which is considerably higher
than the results obtained by novice human (the Organiser team results). For this
task, the common approach was to enrich visual concepts from images through
di erent CNNs, transform everything data to vector through BOW, Word2Vec,
etc., cluster/segment sequential images, and apply di erent feature similarity
search methods to nd images with suitable context and concepts. The best
score was achieved by building object color detectors to extract visual concepts
which adapt to each user's daily life.
        </p>
        <p>In the Puzzle task, four teams have participated and the highest score was
obtained at the value of 0:55 by two runs (RUN03ME and RUN04ME), also from
the HCMUS team. With the exception of the BIDAL team that utilised di erent
functions and visual features to evaluate the similarity between each train-test
pairs and proposed new grouping algorithm to decide query arrangement, most
teams used BOVW to retrieve images from training data, in order to rearrange
the test images based on the temporal order of the retrieved results. The highest
score was achieved by applying BOVW with one million clusters, which would
be a promising approach to conduct further research and improvement.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Discussions and Conclusions</title>
      <p>The submitted approaches in this year con rmed the trend from last year: all
approaches are exploiting multi-modal instead of using only visual information.
We also con rmed the importance of deep neural networks in solving these
challenges: all ten participants are using directly tailored-built deep networks or
exploiting the semantic concepts extracted by using deep learning methods. Unlike
previous editions, we received more semi-automatic approaches, which combine
human knowledge with state-of-the-art multi-modal information retrieval.
Regarding the number of the signed-up teams and the submitted runs, the task
keeps growing, with the highest number of registrations and participated teams.
It is also a great successful that team retention rate is high with two third
nonorganiser teams from last year continued to participate in this year. This again
con rms how interesting and challenging lifelogging is. As next steps, we do not
plan to enrich the dataset but rather provide richer and better concepts, improve
the quality of the queries and narrow down the application of the challenges.
5</p>
    </sec>
    <sec id="sec-5">
      <title>Acknowledgement</title>
      <p>This publication has emanated from research supported in party by research
grants from Irish Research Council (IRC) under Grant Number GOIPG/2016/741
and Science Foundation Ireland under grant numbers SFI/12/RC/2289 and
SFI/13/RC/2106.</p>
      <p>The authors thank to Thanh-An Nguyen, Trung-Hieu Hoang, and the annotation
team of Software Engineering Laboratory (SELab), University of Science,
VNUHCM for supporting in building the data collection as well as giving valuable
discussions for the Lifelog moment retrieval (LMRT) task.
18. Zhou, B., Lapedriza, A., Khosla, A., Oliva, A., Torralba, A.: Places: A 10 million
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