Visual Illusions in Cartography

Arzu Çöltekin, University of Zürich
NACIS 2014

Some visual illusions are exteremely important for the legibility and interpretation of cartographic products; such as the terrain reversal effect in shaded relief maps (in which we perceive convex shapes as concave and vica versa), or change blindness (in which we can't detect the change from one scene to another). Some others, such as Müller-Lyer illusion or Ebbinghaus illusion may also be relevant in estimating distances and areas. This talk provides a brief overview of illusions in Cartography and presents results from an empirical study on terrain reversal effect.

Transcript

1. Arzu  Coltekin   University  of  Zurich   arzu@geo.uzh.ch   @acolt   Visual  Illusions  in  Cartography   Image:    Scien7fic  American,  2008  
2. Ebbinghaus  illusion,  or  Titchener  circles   Source:  Wikimedia  Commons,     Author:  Fibonacci   Müller-­‐Lyer  illusion   Source:  Wikimedia   Commons,  Author:   Fibonacci   EsHmaHng  distances   EsHmaHng  areas   Müller-­‐Lyer  illusion   Source:  Wikimedia  Commons,   Author:  A.  M.  de  Campos  
3. Color  stereo  effect   hKps://twiKer.com/TED_ED/status/486638409771778048  
4. Color  stereo  effect   htwiKer.com/jatorre/status/496423576447516672/photo/1  -­‐  Madrid  from  a  radar  in  space.  #ESA  #Copernicus    
5. Necker  Cube   Source:  Wikimedia  Commons,  Author:  BenFrantzDale   “Bistable  percepHon”     (e.g.,  Kornmeier  &  Bach  2006)  
6. Hollow  mask  illusion   Source:  hKp://www.youtube.com/watch?v=iR9WVhiaIeYm     Uploaded  by:  daarkniight  
7. Rotated  180o   Original   7   hKp://www.cartesia.org/geodoc/icc2005/pdf/oral/TEMA6/Session%208/ANGEL%20BERNABE.pdf   Kleffner  &  Ramachandran  (1992)  
8. Terrain  reversal  (relief  inversion)   Bernabe  and  Coltekin,  2014   Original   180  degree  rotated   Color  inverted   Reference  terrain  model   Bernabe-­‐Poveda,  M.,  Coltekin,  A.  (2014).  Prevalence  of  the  Terrain   Reversal  Effect  in  Satellite  Imagery  .  InternaHonal  Journal  of  Digital   Earth  DOI:  10.1080/17538947.2014.942714  
9. Prevalence   in  satellite  images   Bernabe-­‐Poveda,  M.,  Coltekin,  A.  (2014).  Prevalence  of  the  Terrain  Reversal  Effect  in  Satellite  Imagery  .  InternaHonal  Journal   of  Digital  Earth  DOI:  10.1080/17538947.2014.942714  
10. Prevalence   in  satellite  images   Bernabe-­‐Poveda,  M.,  Coltekin,  A.  (2014).  Prevalence  of  the  Terrain  Reversal  Effect  in  Satellite  Imagery  .  InternaHonal  Journal   of  Digital  Earth  DOI:  10.1080/17538947.2014.942714  
11. Study  I     •  Different  providers   – Google,  Yahoo,  Mapquest,  Bing  all  have  it     •  It  occurs  a  lot  more  in  northern  hemisphere   – Google  59.6%  in  NH,  2.5%  in  SH     Bernabe-­‐Poveda,  M.,  Coltekin,  A.  (2014).  Prevalence  of  the  Terrain  Reversal  Effect  in  Satellite  Imagery  .  InternaHonal  Journal   of  Digital  Earth  DOI:  10.1080/17538947.2014a.942714  
12. Study  I   Online  experiment   – Is  this  a  valley  or  a  ridge?   – Is  A  located  in  a  higher  point  than  B?   Stage  1  (n=224)   NH/SH  images  as  found  online   Stage  2  (n=251)   NHR /SHR  images  rotated  180  degrees     Bernabe-­‐Poveda,  M.,  Coltekin,  A.  (2014).  Prevalence  of  the  Terrain  Reversal  Effect  in  Satellite  Imagery  .  InternaHonal  Journal   of  Digital  Earth  DOI:  10.1080/17538947.2014a.942714  
13. Bernabe-­‐Poveda,  M.,  Coltekin,  A.  (2014).  Prevalence  of  the  Terrain  Reversal  Effect  in  Satellite  Imagery  .  InternaHonal  Journal   of  Digital  Earth  DOI:  10.1080/17538947.2014a.942714   ***   Study  I  
14. Study  II   Biland  and  Coltekin  (2014)  –  paper  in  progress   128  terrains  (8  landform  configuraHons,  16  illuminaHon  direcHons)   29  parHcipants  
15. Biland  and  Coltekin  (2014)  –  paper  in  progress  
16. Study  II   Biland  and  Coltekin  (2014)  –  paper  in  progress  
17. Biland  and  Coltekin  (2014)  –  paper  in  progress  
18. Study  III   Coltekin  and  Biland  (2014)  –  paper  in  progress   33  x  3  terrains   29  parHcipants  
19. Study  III   Hillshades   Gray  scale  satellite   Color  satellite   **   **   Coltekin  and  Biland  (2014)  –  paper  in  progress  
20. Coltekin  and  Biland  (2014)  –  paper  in  progress  
21. Main  findings   -­‐  The  terrain  reversal  thing  is  real   -­‐  Kleffner  &  Ramachandran  (1992)’s  light  from   above  assump<on  is  confirmed   -­‐  Cartographic  insight  (e.g.  Imhof  1965)  for   northwest  illumina<on  is  confirmed   -­‐  with  a  li>le  twist   -­‐  Perceptual  signal  is  contrasted  by  cogniHve   interpretaHon  
22. Can  it  be  corrected?   Yes,  but  needs  work       – Verify  the  proposed  soluHons   – Discover  the  effect  algorithmically   – AutomaHze  the  soluHon   Bernabé-­‐Poveda,  M.  A.,  Sánchez-­‐Ortega,  I.,  &  Çöltekin,  A.  (2011).  Techniques  for  HighlighHng   Relief  on  Orthoimaginery.  Procedia  -­‐  Social  and  Behavioral  Sciences,  21,  346–352.  doi:10.1016/ j.sbspro.2011.07.028  
23. What you see is
24. 40%
25. Thank you arzu@geo.uzh.ch" twitter: @acolt" I  feel  sorry  for  the  comic  sans.  It  reminds  me  of  Pluto.