Land-cover mapping of the central Arizona region based on 2015 National Agriculture Imagery Program (NAIP) imagery
Publication date: 2020-09-25
Author(s):
- Yujia Zhang, Arizona State University
- Billie Turner II, Arizona State University
Abstract:
Detailed land-cover mapping is essential for a range of research issues addressed by sustainability science, especially for questions posed of urban areas, such as those of the Central Arizona-Phoenix Long-Term Ecological Research (CAP LTER) program. This project provides a 1-meter land-cover mapping of the CAP LTER study area (greater Phoenix metropolitan area and surrounding Sonoran desert). The mapping is generated primarily using 2015 National Agriculture Imagery Program (NAIP) four-band data, with auxiliary GIS data used to improve accuracy. Auxiliary data include the 2015 cadastral parcel data, the 2014 USGS LiDAR data (1-meter), the 2014 Microsoft/OpenStreetMap Building Footprint data, the 2015 Street TIGER/Line, and a previous (2010) NAIP-based land-cover map of the study area (https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-cap&identifier=623). Among auxiliary data, building footprints and LiDAR data significantly improved the boundary detection of above-ground objects. Post-classification, manual editing was applied to minimize classification errors. As a result, the land-cover map achieves an overall accuracy of 94 per cent. The map contains eight land cover classes, including: (1) building, (2) asphalt, (3) bare soil and concrete, (4) tree and shrub, (5) grass, (6) water, (7) active cropland, and (8) fallow. When compared to the aforementioned, previous (2010) NAIP-based land-cover map for the study area, buildings and tree canopies are classified more accurately in this 2015 land-cover map.
Keywords:
urban,
land use,
land cover,
land surface properties,
spatial properties,
lidar,
satellite imagery,
imagery,
remote sensing,
geographic information systems land use and land cover change,
urban design national agriculture imagery program,
NAIP cap lter,
cap,
caplter,
central arizona phoenix long term ecological research,
arizona,
az,
arid land
Temporal Coverage:
2015-05-29 to 2015-06-01
Geographic Coverage:
Geographic Description: CAP LTER study area: greater Phoenix, Arizona (USA) metropolitan area and surrounding Sonoran desert region
Bounding Coordinates:
Longitude:-112.8256 to -111.5581
Latitude:33.8871 to 33.1756
Contact:
Information Manager, Central Arizona–Phoenix LTER,
Arizona State University,Global Institute of Sustainability,Tempe
caplter.data@asu.edu
Methods used in producing this dataset:
Show
## Methods and Protocols
The 1-meter land cover map was generated primarily using the 2015 NAIP imagery. It has eight land cover classes and achieved an overall accuracy of 94%. This detailed land cover map was created in the eCognition software using the object-based classification approach. The first step was NAIP image segmentation, where pixels with similar spectral and spatial characteristics were grouped into parcel sized or finer objects. Next, hierarchical rule-based expert systems were developed to classify the objects into specific land cover classes based on their spectral, morphological, and contextual attributes.
Various auxiliary GIS data were utilized to improve classification accuracy. They include the 2015 cadastral parcel data, the 2014 USGS Lidar data (1-meter), the 2014 Microsoft/OpenStreetMap Building Footprint data, the 2015 Street TIGER/Line, and the previous NAIP-based land cover map for the year of 2010. Specifically, building footprints and Lidar data significantly improved the boundary detection of above-ground objects. Compared to the 2010 NAIP-based land cover map, buildings and tree canopy shapes were classified more accurately. Finally, post-classification manual editing was applied to minimize classification errors.
## Land Cover Class Description
| Class ID | Class Name | Description |
|----------|----------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
| 1 | Building | This class contains all types of buildings in residential, commercial, and industrial areas. |
| 2 | Asphalt | This is the dark color impervious surface. This class mainly contains road and parking lots. |
| 3 | Bare Soil & Concrete | This class includes bare soil, sand, gravel, and rock in urban and desert environments. It also contains light color impervious surface such as concrete. |
| 4 | Tree & Shrub& | This class contains trees and shrubs that are higher than 1.5-meter. |
| 5 | Grass& | This class is mainly turf grass. It may also contain shrubs that are lower than 1.5-meter. |
| 6 | Water | This class includes different types of water bodies, such as lake, pond, canal, and swimming pools. |
| 7 | Active Cropland | This class is cropland covered by green vegetation. |
| 8 | Fallow | This class is cropland without green vegetation. |
## Accuracy Assessment Table
| Class | Correctly Classified count | Reference count | Classified count | Producer's Accuracy | User's Accuracy |
|----------------------|----------------------------|-----------------|------------------|-----------------------|-------------------|
| Building | 49 | 49 | 50 | 100.00% | 98.00% |
| Asphalt | 48 | 52 | 50 | 92.30% | 96.00% |
| Bare Soil & Concrete | 45 | 55 | 50 | 81.80% | 90.00% |
| Tree & Shrub& | 46 | 50 | 50 | 92.00% | 92.00% |
| Grass& | 45 | 49 | 50 | 91.80% | 90.00% |
| Water | 49 | 50 | 50 | 98.00% | 98.00% |
| Active Cropland | 48 | 49 | 50 | 98.00% | 96.00% |
| Fallow | 46 | 46 | 50 | 100.00% | 92.00% |
| Overall Accuracy | | | 94.00% | | |
* Producer's accuracy = Correctly Classified count / Reference count
* User's accuracy = Correctly Classified count / Classified count
* Overall accuracy = Sum of Correctly Classified count/ Sum of Reference (or Classified) count
* &: Lidar data only covered 21% of the study area. Within the Lidar data extent, tree and grass achieved higher accuracy >95%. Beyond Lidar coverage, the tree versus grass classification was less accurate due to the lack of surface height information. As a result, tree and grass achieved accuracies of 90% - 92% over the entire study area.
This method step describes provenance-based metadata as specified in the LTER EML Best Practices.
This provenance metadata does not contain entity specific information.
Data Files (6) :
Tabular:
685_accuracy_assessment_3450f3e8c9db5f54201e390e06839630.csv
Description: Accuracy assessment of classification. This data table details classification accuracies for each land-use, land-cover class. Overall accuracy of the classification (sum of correctly_classified_count / sum of reference_count (or classified_count)) was 94%. These data are included with the dataset metadata, and the contents of this file mirrors that information
Column |
Description |
Type |
Units |
class_name |
land-cover category name
|
string |
Enumeration:
-
Active Cropland: This class is cropland covered by green vegetation.
-
Asphalt: This is the dark color impervious surface. This class mainly contains road and parking lots.
-
Bare Soil & Concrete: This class includes bare soil, sand, gravel, and rock in urban and desert environments. It also contains light color impervious surface such as concrete.
-
Building: This class contains all types of buildings in residential, commercial, and industrial areas.
-
Fallow: This class is cropland without green vegetation.
-
Grass: This class is mainly turf grass. It may also contain shrubs that are lower than 1.5-meter. The tree versus grass classification (1.5-meter height threshold) depends on LiDAR data availability. However, the 2014 USGS Lidar data only covered 21% of the CAP study area. Please see 685_LiDAR_extent.kml for more details.
-
Tree & Shrub: This class contains trees and shrubs that are higher than 1.5-meter. The tree versus grass classification (1.5-meter height threshold) depends on LiDAR data availability. However, the 2014 USGS Lidar data only covered 21% of the CAP study area. Please see 685_LiDAR_extent.kml for more details.
-
Water: This class includes different types of water bodies, such as lake, pond, canal, and swimming pools.
|
correctly_classified_count |
count of correctly classified pixels
|
float |
number |
reference_count |
count of reference pixels
|
float |
number |
classified_count |
count of classified pixels
|
float |
number |
producer_accuracy |
correctly_classified_count / reference_count
|
float |
dimensionless |
user_accuracy |
correctly_classified_count / classified_count
|
float |
dimensionless |
Tabular:
685_land_cover_classes_37ee358ab2c5f550bebcc36751f67fe4.csv
Description: companion file to the dataset .tif file that details the corresponding LULC (land use, land cover) type of each raster value; these data are included with the .tif metadata and the contents of this file mirrors that information
Column |
Description |
Type |
Units |
class_id |
land-cover raster value
|
string |
|
class_name |
land-cover category name
|
string |
|
description |
land-cover category description
|
string |
|
Spatial Vector:
685_LiDAR_extent.kml
Description: Areal coverage of 2014 LiDAR data available to support the 2015 land-cover classification. The 2014 USGS Lidar data only covered 21% of the CAP LTER study area. Within the area covered by LiDAR, tree and grass achieved higher accuracy (> 95%); outside the area, the tree versus grass classification was less accurate due to the lack of surface-height information. This LiDAR extent was modified based on the NAIP image tile boundaries. The full 2014 USGS Lidar extent can be accessed from https://lib.asu.edu/Geo/news/New-Web-Map-Accessing-Phoenix-LiDAR-Data
Temporal Coverage: 2014-09-30 to 2014-10-05
Horizontal Coordinate System:GCS_WGS_1984
Geometry Type: Polygon
Column |
Description |
Type |
Units |
Tile_Name |
tile identifier that references corresponding LiDAR data for that location
|
string |
|
Name |
tile identifier that references corresponding LiDAR data for that location
|
string |
|
Raster:
685_land_cover_1m_2015_a8db4e50b4c88ceaf4e11cb73616f316.tif
Description: Fine-resolution (1-meter) land-cover mapping of the CAP LTER study area (greater Phoenix metropolitan area and surrounding Sonoran desert). The mapping is generated primarily using 2015 National Agriculture Imagery Program (NAIP) four-band data, with auxiliary GIS data used to improve accuracy. Auxiliary data include the 2015 cadastral parcel data, the 2014 USGS LiDAR data (1-meter), the 2014 Microsoft/OpenStreetMap Building Footprint data, the 2015 Street TIGER/Line, and a previous (2010) NAIP-based land-cover map of the study area.
Temporal Coverage: 2015-05-29 to 2015-06-01
Horizontal Coordinate System:NAD_1983_UTM_Zone_12N
Rows:77561
Columns:116828
Column |
Description |
Type |
Units |
raster_value |
categorical value indicating LULC (land use, land cover) type
|
string |
Enumeration:
-
1: Building: This class contains all types of buildings in residential, commercial, and industrial areas.
-
2: Asphalt: This is the dark color impervious surface. This class mainly contains road and parking lots.
-
3: Bare Soil & Concrete: This class includes bare soil, sand, gravel, and rock in urban and desert environments. It also contains light color impervious surface such as concrete.
-
4: Tree & Shrub: This class contains trees and shrubs that are higher than 1.5-meter.
-
5: Grass: This class is mainly turf grass. It may also contain shrubs that are lower than 1.5-meter.
-
6: Water: This class includes different types of water bodies, such as lake, pond, canal, and swimming pools.
-
7: Active Cropland: This class is cropland covered by green vegetation.
-
8: Fallow: This class is cropland without green vegetation.
|
File:
685_land_cover_1m_2015_01d2be822e676e572bae5829b3124096.clr
Description: companion file to the dataset .tif file that details a color profile for the .tif raster values
File:
685_land_cover_1m_2015_30df46aeafa3405285513e1435f40973.dbf
Description: companion file to the dataset .tif file that details the corresponding LULC (land use, land cover) type of each raster value; these data are included with the .tif metadata and the contents of this file mirrors that information