• Call for Physical Sciences Papers
  • Sign-up for PNAS eTOC Alerts

Motion microscopy for visualizing and quantifying small motions

  1. William T. Freemana,e,f,2
  1. aComputer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139;
  2. bDepartment of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
  3. cHarvard-MIT Program in Health Sciences and Technology, Cambridge, MA 02139;
  4. dResearch Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139;
  5. eGoogle Research, Google Inc. Cambridge, MA 02139;
  6. fDepartment of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139;
  7. gSchool of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138;
  8. hDepartment of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218;
  9. iHopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, MD 21218
  1. Edited by William H. Press, University of Texas at Austin, Austin, TX, and approved August 22, 2017 (received for review March 5, 2017)

Significance

Humans have difficulty seeing small motions with amplitudes below a threshold. Although there are optical techniques to visualize small static physical features (e.g., microscopes), visualization of small dynamic motions is extremely difficult. Here, we introduce a visualization tool, the motion microscope, that makes it possible to see and understand important biological and physical modes of motion. The motion microscope amplifies motions in a captured video sequence by rerendering small motions to make them large enough to see and quantifies those motions for analysis. Amplification of these tiny motions involves careful noise analysis to avoid the amplification of spurious signals. In the representative examples presented in this study, the visualizations reveal important motions that are invisible to the naked eye.

Abstract

Although the human visual system is remarkable at perceiving and interpreting motions, it has limited sensitivity, and we cannot see motions that are smaller than some threshold. Although difficult to visualize, tiny motions below this threshold are important and can reveal physical mechanisms, or be precursors to large motions in the case of mechanical failure. Here, we present a “motion microscope,” a computational tool that quantifies tiny motions in videos and then visualizes them by producing a new video in which the motions are made large enough to see. Three scientific visualizations are shown, spanning macroscopic to nanoscopic length scales. They are the resonant vibrations of a bridge demonstrating simultaneous spatial and temporal modal analysis, micrometer vibrations of a metamaterial demonstrating wave propagation through an elastic matrix with embedded resonating units, and nanometer motions of an extracellular tissue found in the inner ear demonstrating a mechanism of frequency separation in hearing. In these instances, the motion microscope uncovers hidden dynamics over a variety of length scales, leading to the discovery of previously unknown phenomena.

Footnotes

  • ?1Present address: Google Research, Google Inc. Mountain View, CA 94043.

  • ?2To whom correspondence should be addressed. Email: billf{at}mit.edu.
  • Author contributions: N.W., J.G.C., J.B.S., D.W., M.R., R.G., D.M.F., O.B., S.H.K., K.B., F.D., and W.T.F. designed research; N.W., J.G.C., J.B.S., D.W., R.G., P.W., S.S., S.H.K., and W.T.F. performed research; N.W., J.G.C., J.B.S., and D.W. analyzed data; and N.W., J.G.C., J.B.S., D.W., R.G., D.M.F., O.B., P.W., S.S., S.H.K., K.B., F.D., and W.T.F. wrote the paper.

  • The authors declare no conflict of interest.

  • This article is a PNAS Direct Submission.

  • This article contains supporting information online at www.danielhellerman.com/lookup/suppl/doi:10.1073/pnas.1703715114/-/DCSupplemental.

This is an open access article distributed under the PNAS license.

Online Impact

                                      1. 99132880 2018-01-23
                                      2. 802899879 2018-01-23
                                      3. 295573878 2018-01-23
                                      4. 352668877 2018-01-23
                                      5. 984633876 2018-01-23
                                      6. 545928875 2018-01-23
                                      7. 976569874 2018-01-23
                                      8. 871324873 2018-01-23
                                      9. 263462872 2018-01-23
                                      10. 577161871 2018-01-23
                                      11. 255603870 2018-01-23
                                      12. 117346869 2018-01-23
                                      13. 90982868 2018-01-23
                                      14. 663415867 2018-01-23
                                      15. 793874866 2018-01-23
                                      16. 843582865 2018-01-23
                                      17. 864971864 2018-01-22
                                      18. 258841863 2018-01-22
                                      19. 957295862 2018-01-22
                                      20. 553518861 2018-01-22