1. Antoine Masse, Sidonie Christophe
IGN, COGIT Laboratory
France
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015

2. GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015 2
• Coastal area
Between highest astronomical tide (shoreline)
and lowest astronomical tide (drying line)
• Spatio-temporal objects & phenomena
• Uncertainty: in motion (tides, sands)
• Incompleteness of data: underwater observation problems
• Imprecision: different definitions of an object at different scale
Sea/Land interface
ShorelineDrying line
Point Reyes, California
Red : DTM data (res. 1m, prec. 0,2m)
Yellow : 1:15,000 topomap
Blue : 1:50,000 topomap
Motivation: coastal area geovisualization
Different Shoreline definition

3. 3
Different uses & users  Different geovis
Limitations:
 Visual discontinuities and heterogeneity
between sea & land
 Perception of tides and/or water depth
for non-specialist users
C-Map®, navigation software
ScanLittoral®, Touristic/Public map
Interactive elevation simulation of lake Erie, USA (NOAA)
Ortho-image of La Grande Motte, Google Maps®
Ocean seafloor map of Hawai'i
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015
Motivation: coastal area
geovisualization

4. Purpose of the talk
4
• To convey sea dynamic information to users
Example of tide dynamic for informational purposes
• Hypothesis:
– Using heterogeneous data (maps, ortho-imagery,
LiDAR)…
– … to make homogeneous visualizations between
sea & land
– … by controlling photo-realism/abstraction
– … to convey tides & water depth perception
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015

5. Implementation
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015 5
Lidar acquisition (land/sea)
SHOM
0
5
10
Water elevation (in meters)
Tidal data, REFMAR® project
DTM (land/sea)
SHOM
Resolution: 1m/5m (land/sea)
Vertical precision: 0.2m/0.5m (land/sea)
Style
Rendering Engine Final
Rendering
Perception
Geographic
feature
External
data
Visual
Variables
Inspiration sources Colors, …
Maps, ortho-imagery, …
Abstraction, ortho-image-realism

6. Proposition of
geovisualizations
6
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015
4 examples for water depth visualization, static
and dynamic
Same data, different stylization of water depth:
- Abstraction maps
- (Ortho) photo-realism
0
5
10
Water elevation (in meters)
Data
Inspiration

7. 7
Inspiration: Map abstraction (1:25,000)
Location: Lanildut, Finistère, France
Data: DTM: Litto3D OpenData
Tidal data: REFMAR OpenData
Cartographic database
Color map
1st example: perception of
water depth by intervals
Low tide
05/28/2009
14:00
Depth (m) 0 -5 -10 -20
Color
Uses:
Tourism, Hiking, Fishing
Issues:
≠ producers
≠ uses
no tidal information
(ex: accessibility of Ile de Melon)
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015
High tide
05/28/2009
19:00

8. 8
1st example: perception of water depth intervals
Time x4000
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015

9. 9
Inspiration: Map abstraction
2nd example:
continuous
perception of water
depth
Location: Lanildut, Finistère, France
Data: DTM: Litto3D OpenData
Tidal data: REFMAR OpenData
Cartographic database
Colormap (interpolated)
Low tide
05/28/2009
14:00
High tide
05/28/2009
19:00
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015
Depth (m) 0 -5 -10 -20
Color

10. 10
2nd example: continuous perception of water depth
Time x4000
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015

11. 11
Inspiration: Ortho-image photo-realism
Location: Lanildut, Finistère, France
Data: DTM: Litto3D OpenData
Tidal data: REFMAR OpenData
IGN BD Ortho (land part)
Colormap (interpolated)
3rd example: continuous water depth perception
Depth (m) 0 -5 -10 -20
Color
Uses:
Exploration, landscape survey, …
Issues:
Color gaps
Depth gaps
no tidal information
visualization of a specific tidal stage
Low tide
05/28/2009
14:00
High tide
05/28/2009
19:00
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015

12. 12
3rd example: water depth perception
Brightness +20%
Contrast +40%
Time x4000
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015

13. 13
Location: Vannes, Morbihan, France
Data: DTM: Litto3D® OpenData
Tidal data: REFMAR® OpenData
IGN BD Ortho® (land part)
Colormap (interpolated)
4th example: water depth perception
Depth (m) 0 -5 -10 -20
Color
Uses:
Exploration, landscape survey, …
Issues:
Sands
Sea infiltration at high tide High tide
03/21/2015
16:30
Low tide
03/21/2015
10:20
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015
Inspiration: Ortho-image photorealism

14. 14
4th example: water depth perception
Brightness +20%
Contrast +40%
Time x4000
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015

15. Conclusion
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015 15
Goal: Convey sea dynamic information to geovisualization users
Thoughts for coastal geovisualization:
• Important: Data precision and land/sea visual continuity
 improve water depth perception
• Static and dynamic visualization -> different use, complementary
• Abstraction/Photo-realism: same data, different stylization

16. 16
- User Evaluation: uses and users?
• readability, handling, adaptation to specific use,
integration in final-user applications, etc.
• Task examples: How deep it is? When is it accessible?
- Tool adaptability
• Other data for validation
• Realism improvements
• With new data (ex: seafloor cover)
• With new stylization tools (expressive textures like
waves and sea stream, shaded relief)
Perspectives
Our method with other data
Carmel-by-the-sea, CA, USA
NOAA for DTM (sea) / Google Maps (land)
Shaded relief (Yu, 2005)
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015Water texture

17. Thanks
17
mapstyle.ign.fr antoinemasse.froxygene-project.sourceforge.net/
nice software nice project nice speaker
GeoVIS 2015 - ISPRS Geospatial Week - 10/01/2015