C-CAP Land Cover, Territory of Guam 2016

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NOAA OCM | Source Geospatial Form: remote-sensing image | Type of Source Media: DVD/CD-ROM

This data set was created by Quantum Spatial, Inc. (https://quantumspatial.com/). This version of the classification is the High Resolution Land Cover (2016-era) for the Territory of Guam.

This section outlines the classification procedure for the Guam High Resolution C-CAP. WorldView3 imagery used in producing this land cover product was also utilized in producing an associated impervious surfaces layer for the island. The mapping approach utilized a boundary summary, automated image segmentation, and manual extraction of change and land cover using the 2011 high resolution C-CAP data set, the 2011 WorldView2 imagery, the 2015-2016 WorldView3 imagery, and ancillary data sources to create the 2016 high resolution C-CAP. A calibration visit was not conducted though NOAA had access to local resources for validation. Non impervious features were mapped using a 0.25 acre minimum mapping unit (MMU) and impervious features were mapped using a 0.1 acre MMU.

Pre-processing steps:

The WorldView3 mosaic utilized for this project was provided NOAA as an orthorectified, georeferenced product. The imagery was re-sampled from its native 1.2m spatial resolution to 2.4m to match the spatial resolution of the 2011 C-CAP Land Cover product.

Impervious Update:

The 2011 impervious was over-laid with semi-transparency on the 2015-2016 WorldView3 satellite data. It was panned at a scale of 1:4,500 and manually updated to match the 2015-2016 data. Analysts zoomed in to a larger scale when necessary to perform edits. The product went through a QC procedure to ensure features were accurately captured.

Image Segmentation:

The 2016 impervious was combined with the 2011 land cover to create a hybrid data set. Image segmentation, done in Trimble's eCognition software, was performed at multiple scales using the WorldView3 imagery and existing land cover with updated impervious in order to group like spectral and textural objects within the imagery. The image segments were exported and then brought into ArcGIS. A manual interpretation process was used to collect segments as areas of change. These areas created the change mask.

Classification:

Classification - As segments were collected for change, a land cover class was also assigned to the segment to indicate its new 2016 land cover classification.

Map Finalization - Quantum Spatial used independent reviewer’s comments and NOAA's review comments to further refine the land cover map. Various models and processing tools were also used during this refinement process, such as creating and reviewing a 2011-2016 change matrix and identifying illogical change pixels based on to and from land cover combinations.

Attributes for this product are as follows:

0 Background

1 Unclassified

2 Impervious

3

4

5 Developed, Open Space

6 Cultivated Crops

7 Pasture/Hay

8 Grassland/Herbaceous

9 Deciduous Forest

10 Evergreen Forest

11 Mixed Forest

12 Scrub/Shrub

13 Palustrine Forested Wetland

14 Palustrine Scrub/Shrub Wetland

15 Palustrine Emergent Wetland

16 Estuarine Forested Wetland

17 Estuarine Scrub/Shrub Wetland

18 Estuarine Emergent Wetland

19 Unconsolidated Shore

20 Bare Land

21 Open Water

22 Palustrine Acquatic Bed