|
. (2021). Underwater photogrammetry for close-range 3D imaging of dry-sensitive objects: The case study of cephalopod beaks (Vol. 11).
Abstract: Technical advances in 3D imaging have contributed to quantifying and understanding biological variability and complexity. However, small, dry-sensitive objects are not easy to reconstruct using common and easily available techniques such as photogrammetry, surface scanning, or micro-CT scanning. Here, we use cephalopod beaks as an example as their size, thickness, transparency, and dry-sensitive nature make them particularly challenging. We developed a new, underwater, photogrammetry protocol in order to add these types of biological structures to the panel of photogrammetric possibilities. We used a camera with a macrophotography mode in a waterproof housing fixed in a tank with clear water. The beak was painted and fixed on a colored rotating support. Three angles of view, two acquisitions, and around 300 pictures per specimen were taken in order to reconstruct a full 3D model. These models were compared with others obtained with micro-CT scanning to verify their accuracy. The models can be obtained quickly and cheaply compared with micro-CT scanning and have sufficient precision for quantitative interspecific morphological analyses. Our work shows that underwater photogrammetry is a fast, noninvasive, efficient, and accurate way to reconstruct 3D models of dry-sensitive objects while conserving their shape. While the reconstruction of the shape is accurate, some internal parts cannot be reconstructed with photogrammetry as they are not visible. In contrast, these structures are visible using reconstructions based on micro-CT scanning. The mean difference between both methods is very small (10?5 to 10?4 mm) and is significantly lower than differences between meshes of different individuals. This photogrammetry protocol is portable, easy-to-use, fast, and reproducible. Micro-CT scanning, in contrast, is time-consuming, expensive, and nonportable. This protocol can be applied to reconstruct the 3D shape of many other dry-sensitive objects such as shells of shellfish, cartilage, plants, and other chitinous materials.
Keywords: 3D models cephalopod beaks dry-sensitive material micro-CT scanning micro-photogrammetry underwater photogrammetry
Programme: 109
|
|
|
Niels M. Schmidt, Olivier Gilg, Jon Aars, Rolf A. Ims. (2021). Fat, Furry, Flexible, and Functionally Important: Characteristics of Mammals Living in the Arctic.
Abstract: Mammals constitute a group of vertebrates that share a number of unique characteristics,such as nursing their young with milk, and having hair. The pattern of low mammal species diversity in the Arctic probably reflects a combination of mainly two driving factors: first, being homeotherms, mammals require a substantial amount of energy to sustain the various life processes, and the arctic regions are characterized by a very low availability of energy due to short seasons for primary production. Secondly, the occurrence of arctic mammals today reflects the reinvasion of the mammal species into the Arctic as the ecosystems were re-established following the deglaciation. This chapter discusses the characteristics of the arctic mammals, including their unique adaptations to life, and their role as both consumer and food base in the arctic ecosystems. Climate change in the Arctic may also alter the interactions within food webs.
Keywords: arctic ecosystems Arctic mammals climate change deglaciation food webs homeotherms low mammal species diversity primary production
Programme: 1036
|
|
|
. (2021).
|
|
|
Van Hanja J. (2021).
|
|
|
Meudec L. (2021).
|
|
|
Morgan Godard. (2021).
|
|
|
Crouzet N. (2021). Monitoring warm transiting exoplanets for Ariel with ASTEP+.
|
|
|
Akers P., Savarino, J., Caillon, N. (2021). Reconstructing Antarctic snow accumulation using nitrogen isotopes of nitrate.
|
|
|
Barbero A., Grilli R., Blouzon C., Ahmed S., Thomas J.L., Frey M., Huang Y., Caillon N., Savarino J. (2021). Innovative approach for new estimation of NOx snow-source on the Antarctic Plateau.
|
|
|
Hippolyte LEURIDAN (based in LSCE, internship will be supervised both by LSCE - Michel RAMONET -, and IGE - Olivier MAGAND-, laboratories). (2021). Investigation of Radon measurements as a tracer of atmospheric mercury sources using Amsterdam Island records (Indian Ocean).
Abstract: Since The Signature Of The Minamata Convention On Mercury In 2017, National Regulation Coordinated At An International Level Will Come Into Force In Order To Limit Anthropogenic Emissions And Therefore Protect The Human Health And Ecosystem From This Highly Toxic Pollutant. One Need To Evaluate The Efficiency Of National Measures, And Long-term Monitoring Of Atmospheric Mercury (Hg) Is An Important Tool To Address The Changes Over Time Of Emission Sources, Transport, And Deposition Patterns.the Global Mercury Observation System (Gmos) Project Was Funded By The European Commission (Http://www.gmos.eu) And Started In November 2010 With The Overall Goal To Develop A Coordinated Global Observing System To Monitor Hg On A Global Scale, Including A Large Network Of Ground-based Monitoring Stations. To Date, More Than 40 Ground-based Monitoring Sites Constitute The Global Network Covering Many Regions Where Little To No Observational Data Were Available Before Gmos (Sprovieri Et Al., 2016). All Gmos Work Is Now Continued In The Framework Of The International Frame Work Of Gos4m (Global Observation System For Mercury – Http://www.gos4m.org)although Essential To Fully Understand The Cycling Of Mercury At The Global Scale, Mercury Species Records In The Southern Hemisphere Were Really Scarce Before Gmos. In This Context, An Atmospheric Mercury Monitoring Station Has Been Set Up On Amsterdam Island (37?48 S, 77?34 E) In The Remote Southern Indian Ocean In 2012. Since 2012, We Continuously Measured Gaseous Mercury Species With A 15 Min Frequency. Angot Et Al. (2014) Discussed The First Two Years Of This Record, Using Principally Wind Sector Analysis And Air Mass Back Trajectories. They Also Include In Their Analysis The Unique Continuous Record Of Radon 222 And 220 (Thoron) (Polian Et Al., 1986; Kritz Et Al., 1990). Radon 222 And 220 (Thoron) Activities Can Be Used To Distinguish Local Soil Outgassing From Remote Continental Source. Combined With Meteorological Data, The Change Of Activities Are Then Powerful Tool To Classify Air Mass Origin For The Atmospheric Gaseous Mercury Record. Rapid And Sharp Variations Of Radon 222 Activity, Referred To As &Ldquo;radonic Storms” (Lambert Et Al., 1970) And Ascribed To Strong Continental Air Mass Advection, Are Then Observed At Amsterdam Island. The Occurrence Of Radonic Storms Was Estimated To Be About 4 % In 2012 And 7 % In 2013. Considering The Works Realized In 2014, The Goal Of This Internship Is To Deeper Explore The Relationships Between The Collected Gaseous Elemental Mercury And Observed Radon (222rn / 220rn) Activities In The Entire Data Set. In Particular, We Will Study The Specific And Coupled Trend Of These Compounds, The Frequency And Intensity Of Radonic Storm Occurrence And Their Potential Link With The Gaseous Elemental Mercury Cycle. Local Meteorology Data As Well As Backtrajectories Simulation (Hysplit And/or Flexpart Model) Will Be Also Used.
Programme: 1028
|
|