COCHRAN TEST

Buffer validation on orthoimagery

HARMATI, ATTILA – MOLNÁR, DÁNIEL – SURÁNYI, ANDRÁS – TAKÁCS, KATALIN

Instrument DMC1-122

Spectral bands 4 (RGB, NIR)

Acquisition date 20th June 2013

Spatial resolution 0.5 m

Pixel depth 8 bit

ID SIZE SHAPE BORDER Perimeter Area 1 M SF2 easy 87 637,09 1 427,08

2 M SF3 fuzzy 29 036,93 959,57

3 S SF3 easy 15 558,43 671,69

4 M SF1 fuzzy 76 506,45 1 107,21

5 M SF2 fuzzy 33 177,57 950,49

6 L SF2 fuzzy 143 681,00 1 850,81

7 S SF1 easy 15 910,13 541,08

8 M SF3 easy 58 378,85 2 003,83

9 S SF2 fuzzy 18 859,39 643,35

10 M SF3 fuzzy 86 763,50 1 824,32

11 M SF1 easy 101 248,74 1 267,77

12 S SF1 fuzzy 20 060,73 634,25

13 S SF1 fuzzy 6 077,18 344,18

14 L SF1 fuzzy 167 832,17 1 768,18

15 L SF3 fuzzy 251 763,28 2 780,38

16 S SF1 easy 28 177,46 703,58

17 L SF1 easy 318 898,88 2 376,61

18 S SF3 easy 26 099,76 921,93

19 L SF3 fuzzy 114 999,29 2 457,17

20 L SF3 easy 172 898,67 2 358,72

21 S SF2 easy 25 031,46 775,67

22 S SF2 easy 11 298,34 526,79

23 L SF2 easy 108 682,31 1 551,94

24 M SF1 fuzzy 102 695,84 1 395,43

25 L SF1 fuzzy 191 799,22 1 790,18

26 L SF3 fuzzy 157 593,87 2 577,73

27 L SF2 easy 292 756,29 2 612,16

28 M SF2 easy 104 326,94 1 532,14

29 M SF2 easy 75 638,36 1 344,71

30 S SF3 fuzzy 13 035,50 670,42

O

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P A R C E L

S E L E C T I O N

6 operators: 3 expert 3 skilled

4 repetitions

INTERPRETATION

7 single observations and 0 sets discarded

6 stragglers 4 outliers

CONCLUSION The outlier detection tests discarded many doubtful interpretation cases The Grubbs’ tests on sets resulted no data elimination, showing operator’s decisions on a similar background The Cochran test detected outliers, so the operators may decide different during the repetitions There was neither LPIS nor field measurement reference data applied; only reference data used at later control was the interpretation of expert operators

6 single observations and 0 sets discarded

6 single observations and 2 sets discarded

2 single observations and 0 sets discarded

0 set discarded

COCHRAN TEST

GRUBBS’ single obs.

GRUBBS’ single obs.

C A L C U L A T I O N

O F

B U F F E R

T O L R A N C E

O U T L I E R

D E T E C T I O N

T E S T S

Example for discarded single

observations after the first Grubbs’ test

Example for discarded single

observations after the first Grubbs’ test

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. SRj2 (m4) 5 327 481,31 1 347 878,31 332 125,65 680 906,95 1 586 748,90 410 335,10 107 847,68 88 774,91 72 268,11 55 816,17 41 793,04 257 407,65 58 430,77 1 721 079,33 830 315,13 50 856,02 125 669,88 91 367,16 2 437 526,80 88 470,12 74 817,21 11 618,43 433 145,19 233 110,93 78 451,77 167 789,11 241 654,71 178 526,45 57 891,95 433 366,59

SRj (m2) 2 308,13 1 160,98 576,30 825,17 1 259,66 640,57 328,40 297,95 268,83 236,25 204,43 507,35 241,72 1 311,90 911,22 225,51 354,50 302,27 1 561,26 297,44 273,53 107,79 658,14 482,82 280,09 409,62 491,58 422,52 240,61 658,31

Reference perimeter (m) 1 427,08 959,57 671,69 1 107,21 950,49 1 850,81 541,08 2 003,83 643,35 1 824,32 1 267,77 634,25 344,18 1 768,18 2 780,38 703,58 2 376,61 921,93 2 457,17 2 358,72 775,67 526,79 1 551,94 1 395,43 1 790,18 2 577,73 2 612,16 1 532,14 1 344,71 670,42

SRj in buffer (=SRj/perimeter) 1,62 1,21 0,86 0,75 1,33 0,35 0,61 0,15 0,42 0,13 0,16 0,80 0,70 0,74 0,33 0,32 0,15 0,33 0,64 0,13 0,35 0,20 0,42 0,35 0,16 0,16 0,19 0,28 0,18 0,98

Buffer limit = 2,8 SRj in buffer 4,53 3,39 2,40 2,09 3,71 0,97 1,70 0,42 1,17 0,36 0,45 2,24 1,97 2,08 0,92 0,90 0,42 0,92 1,78 0,35 0,99 0,57 1,19 0,97 0,44 0,44 0,53 0,77 0,50 2,75

Example for discarded set after the second

Grubbs’ test

3 outliers 1 stragglers

0 set discarded

GRUBBS’ sets

0 set discarded

Mean buffer limit: 1,3967 RESULTS

GRUBBS’ pairs of set

EXPERIENCIES This validation method qualifies rather the interpretation/skills of the operators, than the quality of the image (e.g. under tree crowns) At least application of reference phisycal block boundaries was to be advised, since this would filter out uncertainties at difficult boundaries The validation method in its recent form is rather conform to on the spot GPS measurements than to image resolution and tolerance calculations