Napa County Aerial Imagery 2011

This tiled imagery service represents a snapshot of the land surface within Napa County and is made available for public use. The tile cache scheme follows the ArcGIS Online Model and can viewed down to ~1:283 scale. A hard copy of this data is also available directly from the GIS Team. For more information, contact [e-mail]. Extent and Resolution: Ortho-imagery and Oblique imagery within Napa County, California. Projection: State Plane Coordinate System 1983 California Zone 2 North American Datum 1983 (2011) NAVD88 US Survey Feet Capture Window: Imagery was obtained in April 2011 Bands: 3 (RGB) Information about Capture: To produce the color digital orthophotos with a 0.3 meter pixel GSD, Woolpert obtained aerial photography according to the following specifications: Camera: Leica ADS80-SH81/82 Airborne Digital Sensor Flying Height: 9,600' AGL for a nominal 0.3 meter pixel GSD Imagery Type: RGB+NIR Side Lap: 30% The imagery was acquired using the Leica ADS80-SH81/82 multispectral scanner. The fundamental resolution of the imagery was 1.0 foot. The ADS80-SH81/82 utilizes the Applanix POSAV direct positioning and orientation system that is based on airborne GPS and inertial measurement unit (IMU) technology. POSAV data were reduced using the Applanix POSPAC software package (V4.3). All of the source imagery was processed using the Leica GPRO (V3.2) software package. This package provides the capability to perform digital mage processing, aerial triangulation, and image rectification. The strips of imagery were ortho rectified to existing digtial elevation model (DEM) data. The individual rectified strips of ortho rectified imagery were then mosaicked together to form a seamless imagery database over the entire task order area using the OrthoVista software (V4.3) by Inpho GmbH. The final digital orthophoto imagery tiles were extracted using OrthoVista. Accuracy of Orthophotography: For questions regarding use and access, please contact [e-mail].

本切片影像服务（tiled imagery service）为加利福尼亚州纳帕县境内地表的快照数据，面向公众开放使用。其瓦片缓存方案（tile cache scheme）遵循ArcGIS在线模型（ArcGIS Online Model），可缩放至约1:283的比例尺查看。地理信息系统（GIS）团队可直接提供该数据的纸质副本。如需更多信息，请联系邮箱[e-mail]。
范围与分辨率：加利福尼亚州纳帕县境内的正射影像（Ortho-imagery）与倾斜摄影影像（Oblique imagery）。
投影：1983州平面坐标系（State Plane Coordinate System）加利福尼亚2区，1983北美大地基准（North American Datum 1983，2011版），美国垂直基准88（NAVD88），单位为美国测量英尺（US Survey Feet）。
采集时段：影像采集于2011年4月。
波段：3波段（RGB）。
采集信息：为生成像素地面采样距离（GSD）为0.3米的彩色数字正射影像，伍尔珀特公司（Woolpert）按照以下规范获取航空摄影数据：相机：徕卡ADS80-SH81/82机载数字传感器（Leica ADS80-SH81/82 Airborne Digital Sensor）；离地高度（AGL）：9600英尺，以实现标称0.3米的像素地面采样距离；影像类型：RGB+近红外（NIR）；旁向重叠率：30%。
本次影像采集使用徕卡ADS80-SH81/82多光谱扫描仪（multispectral scanner），影像基础分辨率为1.0英尺。该设备搭载了基于机载GPS与惯性测量单元（IMU）技术的Applanix POSAV直接定位与定向系统。POSAV数据通过Applanix POSPAC软件包（V4.3）进行处理。所有原始影像均通过徕卡GPRO（V3.2）软件包完成处理，该软件支持数字影像处理、空中三角测量（aerial triangulation）与影像纠正（image rectification）作业。影像条带已基于现有数字高程模型（DEM）数据完成正射纠正。随后，利用Inpho GmbH公司的OrthoVista软件（V4.3），将各条已纠正的正射影像镶嵌为覆盖整个任务区域的无缝影像数据库（seamless imagery database）。最终的数字正射影像瓦片通过OrthoVista软件导出。
正射影像精度：关于影像使用与访问的相关问题，请联系邮箱[e-mail]。