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The MODIS Land Cover Product MODIS Land Cover Team Boston University GLC 2000 – “FIRST RESULTS” WORKSHOP JRC – Ispra, 18-22 March 2002.

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Presentation on theme: "The MODIS Land Cover Product MODIS Land Cover Team Boston University GLC 2000 – “FIRST RESULTS” WORKSHOP JRC – Ispra, 18-22 March 2002."— Presentation transcript:

1 The MODIS Land Cover Product MODIS Land Cover Team Boston University GLC 2000 – “FIRST RESULTS” WORKSHOP JRC – Ispra, March 2002

2 Terra Launch on December 18,1999

3 MODIS Land Bands

4 MODIS Land Cover Product Objective: –Provide a simple land-cover categorization for biophysical parameterization for GCM, hydrologic, and carbon cycling models

5 MODIS Land Cover Product: Features –Categorizes land cover according to life-form, cover and height of dominant vegetation type following IGBP-DIS scheme –Uses data from spectral and temporal domains –Relies on advanced classifier technology—i.e., decision trees—in a supervised classification mode –Network of global test sites used for algorithm calibration and validation –At-launch 1-km database derived from AVHRR heritage –Level 3, 1-km spatial resolution, 96-day product; Climate Modeler’s Grid (1/4°) product also available

6 Recent Global Land Cover Products Beta Product, released April 15, 2001 –Based on 2 16-day periods of Normalized BRDF-Adjusted Reflectance (NBARs) Provisional Product , released June 15, 2001 –Based on 9 16-day periods of NBARs within July 11– January 15, 2001 –Uses prior probabilities to help separate agriculture and natural vegetation –Includes IGBP classification, secondary classes, confidence measures –Draws from at-launch product when only 0–2 views are available or when classification confidence is less than 40%

7 Recent Global Land Cover Products, Cont. Validated Product –Due 15 April 2002 –Based on MODIS data from 2001 –Includes 4 sets of labels, per-pixel confidence measures, second choices

8 IGBP Land Cover Units (17) Natural Vegetation (11) –Evergreen Needleleaf Forests –Evergreen Broadleaf Forests –Deciduous Needleleaf Forests –Deciduous Broadleaf Forests –Mixed Forests –Closed Shrublands –Open Shrublands –Woody Savannas –Savannas –Grasslands –Permanent Wetlands Developed and Mosaic Lands (3) –Croplands –Urban and Built-Up Lands –Cropland/Natural Vegetation Mosaics Nonvegetated Lands (3) –Snow and Ice –Barren –Water Bodies

9 The Land Cover Input Database Surface Reflectance –Nadir-adjusted surface reflectance, 7 land bands Vegetation Index –MODIS Vegetation Index, maximum value composite Spatial Texture from 250-m Band 2* –Standard deviation-to- mean ratio in Band 2 (near-infrared), maximum value composite in 32-day period *To be added later Snow Cover* –MODIS Snow Cover Product, number of days with snow cover Land Surface Temperature* –MODIS Land Surface Temperature, maximum value composite Directional Information* –Bidirectional reflectance model choices from BRDF product Ancillary Data –DEM,* Land/Water mask

10 Global Composite Map of Nadir BRDF-Adjusted Reflectance (NBAR) April 7– km resolution, Hammer-Aitoff projection, produced by MODIS BRDF/Albedo Team no data MODLAND/Strahler et al. No data True color, MODIS Bands 2, 4, 3

11 MODIS Nadir BRDF-Adjusted Reflectance May 25–June False Color Image NIR–Red–Green

12 NBAR Time Trajectories

13 NDVI EVI MODIS 500 m Vegetation Indices MOD13A1 16 day Composite (September 30 – October 15, 2000 MODLAND/Huete et al

14 Test Sites IGBP-DIS Core/Confidence Sites –Random stratified sampling of classes on IGBP Global Land Cover Product –425 sites identified; 413 SPOT and TM scenes acquired; 91% migrated to WWW by BU BU STEP Database –2614 training sites from 645 TM scenes (6/6/00) –About 1000 training sites in current use for supervised classification

15 DISCover Core Validation Sites

16 Supplemental BU Training Sites

17 STEP Database STEP: –System for Terrestrial Ecosystem Parameterization Key STEP Parameters –Life form, height, cover fraction, of layers –Leaf type, phenology, periodicity, physiognomy of dominants in layers –Elevation, moisture regime, perturbation –Classifications: IGBP, BU, EDC SLCRs –Simple description of site and type (words) STEP Flexibility –Allows application of many different land cover labeling schemes by inference of label from parameters in database

18 MODLand Support Products Six Biomes for LAI / FPAR Algorithm –Used by Ranga Myneni’s radiative transfer model in retrieving LAI and FPAR Six Biomes for Net Primary Productivity (NPP) –Used by Steve Running’s Biome-BGC model in making the MODIS NPP product Fourteen Classes—University of Maryland Legend –We also provide a 14-class product using the University of Maryland scheme –Preferred by some modelers

19 Provisional Land Cover Product June 01

20 Northeast Provisional Land Cover Product, Jul 00–Jan 01 Agriculture Agriculture/Natural Vegetation Mosaic Mixed Forest Evergreen Needleleaf Forest Deciduous Broadleaf Forest Urban

21 Classification Confidence Map Second Most-Likely Class

22 Land Cover Validation Statistical Assessment Based on Site Data –Cross-validation provides probability estimate for errors of omission/commission Two sets of site data: –DISCover Core/Confidence sites—Random stratified sample based on DISCover Land Cover map (Loveland et al., EDC) –Supplemental sites compiled at BU—no explicit sampling design, but large N

23 Validation: Accuracy Assessment Classification Accuracy from Cross- Validation of Training Sites –Hide 20 percent of training sites, classify with remaining 80 percent; repeat five times for five unique sets of all sites –Provides “confusion matrix” –Not a stratified random sample, but a good within-class indication of accuracy

24 Confusion Matrix Global Test Site Confusion Matrix—Provisional Product

25 Per-Pixel Confidence Output Per-pixel Confidence –Based on statistical “boosting” theory –Allows decision-tree classifier to estimate probability of classification associated with each possible class label –Output for label with highest probability for each pixel

26 Validation: Other Datasets Comparison with Community Benchmark Datasets –Global (e.g., DISCover, UMd from AVHRR) Comparison with independent maps derived from high resolution data, e.g., –Humid Tropics: Landsat Pathfinder –Forest Cover: FAO Forest Resources Assessment –Western Europe: CORINE –United States: USGS/EPA MLRC –United States: California Timber Maps (McIver and Woodcock)

27 Validation: Comparisons Collaborative Comparisons –BigFoot sites –MODLand Test Sites

28 Reprojection of BigFoot UTM maps to ISIN BigFoot Results

29 Conclusions MODIS Land Cover Product –Draws on AVHRR heritage –Utilizes improved data and techniques –Top-down, globally-consistent approach –Validation plan emphasizes multiple approaches to build confidence –“Validated” product to be released about 15 April 2002 based on 2001 data


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