2D Building Footprints

Connecticut Statewide Building footprints were created during the CT Statewide GIS Services lidar project. Building footprints are reviewed against lidar intensity imagery to verify completeness of capture. Dataset Description: The data was developed based on a horizontal datum/projection of NAD83 (2011), State Plane Connecticut, U.S. Survey Feet and vertical datum of NAVD88 (GEOID18), U.S. Survey Feet. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 23,381 individual 2,500 ft x 2,500 ft tiles, as tiled Intensity Imagery, and as tiled bare earth DEMs; all tiled to the same 2,500 ft x 2,500 ft schema. Maximium Surface Height Raster and Swath Separation Image tiles 025645_se, 080655_ne, 085655_ne, 085655_nw, 090655_nw, 110660_se, and 135665_se do not exist in the deliverables due to all of the points in the cooresponding LAS tiles being flagged as withheld. LAS file 110660_se is all water and contains no lidar returns, this file does not exist in the deliverables. Ground Conditions: Lidar was collected in Spring 2023, while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Dewberry established a total of 38 ground control points that were used to calibrate the lidar to known ground locations established throughout the CT Statewide GIS Services project area. An additional 247 independent accuracy checkpoints, 145 in Bare Earth and Urban landcovers (145 NVA points), 102 in Tall Grass and Brushland/Low Trees categories (102 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data Geographic Extent Coverage: State of Connecticut Classifications Sensitivity: Public Usage: Public Use Quality: High Quality Known Quality Issues: None known, but subject to standard limitations of third-party commercial data Currency Created: 2023 Update Frequency: Per Flight Last Updated: August 2023 Building Layer will be updated after the completion of the 2026 flight.康涅狄格州全域建筑轮廓（building footprint）数据集由康涅狄格州全域地理信息服务（GIS）激光雷达项目生成。已通过激光雷达强度影像对建筑轮廓进行复核，以验证采集完整性。 数据集说明： 本数据采用的水平基准面/投影为NAD83（2011）康涅狄格州州平面坐标系，单位为美制测量英尺（U.S. Survey Feet）；垂直基准面为NAVD88（GEOID18），单位亦为美制测量英尺。 激光雷达数据以处理完成的分类LAS 1.4格式文件交付，共包含23381幅独立的2500英尺×2500英尺瓦片；同时交付分幅强度影像及分幅裸地数字高程模型（Digital Elevation Model，DEM），所有数据均采用统一的2500英尺×2500英尺瓦片格式规范。 最大表面高程栅格及条带分离影像瓦片025645_se、080655_ne、085655_ne、085655_nw、090655_nw、110660_se及135665_se未在交付成果中提供，原因是对应LAS瓦片内的所有点云均被标记为扣留点。LAS文件110660_se覆盖全水域，无有效激光雷达回波数据，因此该文件未纳入交付成果。 地面采集条件： 激光雷达数据采集于2023年春季，当时地面无积雪，河流水位处于正常或低于正常水平。为对激光雷达数据进行后处理以满足任务订单规范及美国摄影测量与遥感学会（ASPRS）垂直精度指南要求，Dewberry共布设38个地面控制点，用于将激光雷达数据校准至康涅狄格州全域GIS服务项目区内已知的地面坐标点。额外布设247个独立精度检查点，其中145个位于裸地与城市土地覆盖类型区（145个NVA点），102个位于高草、灌丛/低矮树木区（102个VVA点），用于评估本数据的垂直精度。上述检查点未用于本数据的校准或后处理工作。 地理覆盖范围： 康涅狄格州全域 分类标准： 涉密等级：公开 使用权限：公开使用 数据质量：高质量 已知质量问题：无已知质量问题，但需遵循第三方商业数据的标准限制 数据生成时间：2023年 更新频率：按飞行任务周期更新 最近更新时间：2023年8月 建筑轮廓图层将于2026年飞行任务完成后进行更新。