Accuracy assessment of land cover

Accuracy assessment of land cover

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  Accuracy Assessment of Land Cover. KabirUddin, GIS and Remote Sensing Specialist International Centre for Integrated Mountain Development GPO Box 3226, Kathmandu, Nepal Tel +977-1-5003222 Fax +977-1-5003277 Web www.icimod.org Email: Kaibir.Uddin@icimod.org kabir.uddin.bd@gmail.com
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  Accuracy Assessment What isthe accuracy of land cover Have you done land cover validation Have you done land cover validation Most common questions from the remote sensing expert about land cover – Assess how well a classification worked – Understand how to interpret the usefulness of someone else’s classification
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  Accuracy Assessment
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  Selection of qualityTM image ACQUISITION DATE = 2009-03-05 ACQUISITION DATE = 2009-12-02 ACQUISITION_DATE = 2010-01-19
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  Comparison land coverimage with TM and Google earth images
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  Accuracy Assessment: ReferenceData • Some possible sources – Aerial photo interpretation – Ground truth with GPS – GIS layers – Google earth image
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  Sampling Methods Simple RandomSampling : observations are randomly placed. Stratified Random Sampling : a minimum number of observations are randomly placed in each category.
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  Sampling Methods Systematic Sampling: observations are placed at equal intervals according to a strategy. Systematic Non-Aligned Sampling : a grid provides even distribution of randomly placed observations.
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  Sampling Methods Cluster Sampling: Randomly placed “centroids” used as a base of several nearby observations. The nearby observations can be randomly selected, systematically selected, etc...
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  Accuracy Equations 100'Pr X classthatforchosensamplesofnumberTotal classgivenainclassifiedcorrectlysamplesofNumber accuracysoducer= 100' X selectedsamplesentireofoutgroup thatinclassifiedsamplesofnumberTotal groupthatinsamplesselectedthefromclass givenainclassifiedcorrectlysamplesofNumber accuracysUser = 100X samplesclassifiedcorrectlyofnumberTotal chosensamplesreferenceofNumberTotal accuracyOverall =
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  Accuracy Assessment: Compare •Example: Reference Plot ID Number Class determined from reference source Class claimed on classified map Agreement? 1 Conifer Conifer Yes 2 Hardwood Conifer No 3 Water Water Yes 4 Hardwood Hardwood Yes 5 Grass Hardwood No
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  User’s Accuracy Class typesdetermined from reference sourcereference source Class types determined from classified map # Plots Conifer Hardwood Water Totals Conifer 50 5 2 57 Hardwood 14 13 0 27 Water 3 5 8 16 Totals 67 23 10 100 %88100* 57 50 ,' ==Accuracy ConifersUser Example: Conifer 100' X selectedsamplesentireofoutgroup thatinclassifiedsamplesofnumberTotal groupthatinsamplesselectedthefromclass givenainclassifiedcorrectlysamplesofNumber accuracysUser =
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  Producer’s Accuracy Class typesdetermined from reference sourcereference source Class types determined from classified map # Plots Conifer Hardwood Water Totals Conifer 50 5 2 57 Hardwood 14 13 0 27 Water 3 5 8 16 Totals 67 23 10 100 %75100* 67 50 ==Accuracy Coniferproducers, Example: Conifer 100'Pr X classthatforchosensamplesofnumberTotal classgivenainclassifiedcorrectlysamplesofNumber accuracysoducer =
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  Overall (Total) Accuracy •Total accuracy – Total Accuracy: Number of correct plots / total number of plots Class types determined from reference sourcereference source Class types determined from classified map # Plots Conifer Hardwood Water Totals Conifer 50 5 2 57 Hardwo od 14 13 0 27 Water 3 5 8 16 Total s 67 23 10 100 %71100* 100 81350 = ++ =AccuracyTotal Diagonals represent sites classified correctly according to reference data Off-diagonals were mis-classified 100X samplesclassifiedcorrectlyofnumberTotal chosensamplesreferenceofNumberTotal accuracyOverall =
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  Accuracy assessment reportof Nepal Land cover ERROR MATRIX Overall Classification Accuracy = 85.13%
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  Accuracy assessment reportof Nepal Land cover Overall Classification Accuracy = 89.91%
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  Thank you