1. Visual Interpretation for Forest Change Detection in Fiji Vilisi Tokalauvere SOPAC Pacific GIS&RS Conference November 2011 Lotus Building, Suva

2. Purpose of Forest Mapping Direct comparison of digital forest layers 1991 and 2001 did not workDirect comparison of digital forest layers 1991 and 2001 did not work Layer 1991 and layer 2001 had to be adjusted through visual image interpretationLayer 1991 and layer 2001 had to be adjusted through visual image interpretation Forest layers 1991 and 2001 had to be geometrically correctedForest layers 1991 and 2001 had to be geometrically corrected

3. Why visual interpretation? Pacific Island Country conditions are different!Pacific Island Country conditions are different! –Transparent work –Local knowledge added –Difficult atmospheric conditions

4. Forest Cover Mapping 1991 Supervised maximum likelihood classification with DTM involvementSupervised maximum likelihood classification with DTM involvement Conducted by a company in northern GermanyConducted by a company in northern Germany

5. Forest Function Map 1992 Raster data GIS application

6. Forest Inventory 2006 Conducted with image data recorded 2001/2002Conducted with image data recorded 2001/2002 Condition maximum likelihood classificationCondition maximum likelihood classification Solution: Unsupervised classification with maximum visual interactionSolution: Unsupervised classification with maximum visual interaction Mask buildingMask building Reducing 3 forest densities (1991) to 2Reducing 3 forest densities (1991) to 2

7. Water Mask Applied

8. Digitising in MapInfo

9. ERDAS Mangrove Mask Mangrove mask Vanua Levu

10. HazeHaze Different thresholds

11. Visual Interpretation MangroveForest Pine Plantation

12. Digitising

13. Decisions During Digitising Clouds Y/N ? Yes Digitising from Forest Layer 1991 No Digitising from Plantation Layer 1991 Yes Plantation area Y/N ? Digitising from both image backdrops No

14. Toggle between Backdrops

15. Digitising 1991 Layer

16. Digitising 2001 Forest Layer

17. 10x 10 km GRID

18. Description Database

19. Vector to Raster

20. MapInfo to ERDAS Forest, Mangrove polygons exported (DXF) to ERDAS.Forest, Mangrove polygons exported (DXF) to ERDAS. Add Projection.Add Projection. Convert to raster.Convert to raster. Add to forest cover layer.Add to forest cover layer.

21. Reducing to Mappable Area Size Clump Eliminate Cluster No. 2384 1.2 ha All clusters < 1 hectare are joined with the next biggest neighbour class

22. 1Hectare Accumulation

23. Field Verification

24. Next.. Fiji Department of Agriculture – agriculture, bare land, pasture landFiji Department of Agriculture – agriculture, bare land, pasture land

25. Vinaka !