Relief inversion effect in terrain representations: Where should we place the light source?

1. Relief inversion effect in terrain represen-
tations: Where should we place the light
source?
Julien Biland, Dr. Arzu Coltekin
ISPRS Geospatial Week 2015, 1 October 2015
?
Biland and Coltekin (accepted). An empirical assessment of the impact of the light direction
on relief inversion effect in shaded relief maps: NNW is better than NW.
Cartography and Geographic Information Science (CaGIS)

2. Julien Biland & Arzu Coltekin
The
red
dots
appear
to
lie
on..?
Quickbird image
Xinjiang, China
Ridge

3. Julien Biland & Arzu Coltekin
And
image
upside
down
Quickbird image
Xinjiang, China
Ridge

4. Julien Biland & Arzu Coltekin
The
red
dots
appear
to
lie
on..?
Ikonos image
Mt Richmond, New Zealand
Ridge

5. Julien Biland & Arzu Coltekin
And
image
upside
down
Ikonos image
Mt Richmond, New Zealand
Ridge

6. Julien Biland & Arzu Coltekin
Contradic8ons?
Quickbird image
Chagang, North Korea
Valley

7. Julien Biland & Arzu Coltekin
Contradic8ons?
§ Geo-knowledge can hint that your perception is wrong
§ and maybe it overrides your initial shape perception
§ Shape perception dependent on:
§ Familiarity
§ Assumption of light position
§ Convexity-bias

8. Julien Biland & Arzu Coltekin
How
to
judge
true
landform
shape
in
SRM?
Ridge
Caucasus

9. Julien Biland & Arzu Coltekin
Land
cover
helps
Quickbird image
Caucasus
Ridge

10. Julien Biland & Arzu Coltekin
Influence
of
light
direc8on

11. Julien Biland & Arzu Coltekin
§ Illumination position very crucial
§ Which direction is best?
§ Come see our poster P33 to find out
Conclusion

12. Julien Biland & Arzu Coltekin
Thank
you
for
your
aEen8on!
Valley in Russia
Ikonos image