lucas monitoring the european union territory using a grid approach maxime kayadjanian eurostat f-2

LUCAS

LUCAS Monitoring the European Union territory

using a grid approach

Maxime KAYADJANIANEurostat F-2

LUCAS

100 000 points systematically sampled

LUCAS Grid

Reason: compromise between budget and required statistical representativity at EU level

LUCAS

Why a systematic GRID ?

LUCAS Grid

LUCAS is a multipurpose system for monitoring:

• Land Use / Land cover

• Landscape and Environmental features

Reason: all the territory has to be covered the same way to ensure equiprobabilty of observations

LUCAS

300 m

300

m

Specifications

LUCAS Grid

A two-stage sampling GRID

10.000 PSU 10 SSU

Reason: optimizing trip for visiting points in the field

X

LUCAS

Particular case

LUCAS Grid

Italy Spain

Reason: complying with already existing national system

MAST system

Distance inter PSU =

• 20 km (not 18 km)

AGRIT system

Distance inter SSU =

• 300 m east-west

• 500m north-south

LUCAS

Construction of the GRID

LUCAS

Construction (1/3)

LUCAS Grid

Choice of projection

system:

GRS80 + UTM

One sampling plan per

country to limit ground

distortion

LUCAS

Construction (2/3)

LUCAS Grid

Grid generated in the UTM zone of the country

Origin chosen pseudo-randomly Total coverage of country

LUCAS

Construction (3/3)

LUCAS Grid

SSUs selected according to SABE and SCOLE (© Megrin) boundaries

Selection of SSUs Uncompleted PSUs

LUCAS

Geometrical quality of the sampling plan

LUCAS Grid

LUCAS


LUCAS Grid

Are points regularly spread on the ground?

N

S

18 km18 km

N

S

18 km

18 km ?

EW

N

S

18 km

Once grid generated... …in the UTM projection system...

…how much ground distance is affected ?

LUCAS

LUCAS Grid

Largest line of PSUs in France...

24,05

24,10

24,15

24,20

24,25

24,30

24,35

24,40

24,45

24,50

4 9 14 19 24 29 34 39 44 49 54

n° PSU

1/10

0 d

egre

e

Meridian 30 Meridian 31-3° +3°

PSU col n°

…shows a longitudinal angle reduction apart from central meridian

- 45m

…it corresponds to a reduction of 45m on the ground 500 km apart from central meridian.


LUCAS

LUCAS Grid

How many points are affected by distortion ?

Point out of central median zone 30%


Conclusion: distortions are negligible for statistical estimates

LUCAS

The case of SPAIN (MAST)

No distortion but small gaps

LUCAS Grid


LUCAS

Reaching the point on the ground

LUCAS Grid

A fundamental aspect to ensure a correct monitoring

LUCAS


3 basic tools

LUCAS Grid

3/ GPS for navigating along transects

1/ Topographical maps for navigating between PSUs

2/ Aerial photo for reaching precisely the SSU

LUCAS


LUCAS Grid

Observation unit

Point location

10 m

0.5 / 2.5 m

1 m

3 m

GPS

DGPS

Image resolution

Orthophoto

5 m Map: 1/25 000

1 m

Positional accuracy

3 m

At the point: observation in a 3 m window

LUCAS


LUCAS Grid

Country Resolution /Scale

Year Type Use ofGPS

AT 0,5 m 1990/2000 Orthophoto Yes

BE 1 m 1995/2000 Orthophoto Yes

DE 0,25 to 0,8 m

>1995Orthophoto

& aerial photoyes +DGPS

DK 0,4m 1999 Orthophoto yes

ES 0,75 to 2 m

1985/2000Orthophoto

& aerial photono

FI 1 m 1996 Orthophoto yes

FR 0,5 to 1 m >1995Orthophoto

& aerial photono

GR 1 m 1990/1998 Orthophoto yes

IT 1 m ? Orthophoto yes

LU 1/5000 1997 Topogr. map yes

NL 1m >1995 Orthophoto DGPS

PT 1 m 2000 Orthophoto yes

SE 1 m >1995 Orthophoto Yes

LUCAS

Implementation problem

Projection of UTM x,y into national system

LUCAS Grid

Systematic shift of about 200 m between GPS co-ordinates and location on the photo detected during the ground mission control, in:

• Luxembourg: specific parameters for datum

• Greece & Portugal: bug in the GIS soft

For these countries the original sampling plan has been corrected in return

LUCAS

Conclusion

• Reaching the point: Good quality of field document

• Location of points: only minor distortion in the sampling plan (no impact on estimates)

• Well documented

LUCAS can be considered as a strong system:

lucas monitoring the european union territory using a grid approach maxime kayadjanian eurostat f-2

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