USGS 3DEP Elevation - 30 m

This dynamic image service provides float values representing ground heights in meters, based on 3DEP seamless 1 arc-second data from USGS 3D Elevation Program (3DEP). Heights are orthometric (sea level = 0), and water bodies that are above sea level have approximated nominal water heights. Height units: Meters Typical Update Frequency: Annually Coverage: conterminous United States, Hawaii, Alaska, Puerto Rico, Territorial Islands of the United States; Canada and Mexico. Data Source: The data for this layer comes from 3DEP seamless 1 arc-second dataset from the USGS's 3D Elevation Program with original source data in its native coordinate system. What can you do with this layer? Use for Visualization: This layer is generally not optimal for direct visualization. By default, 32 bit floating point values are returned, resulting in higher bandwidth requirements. Therefore, usage should be limited to applications requiring elevation data values. Alternatively, client applications can select from numerous additional functions, applied on the server, that return rendered data. For visualizations such as hillshade, slope, consider using the appropriate server-side function defined on this service. Use for Analysis: Yes. This layer provides data as floating point elevation values suitable for use in analysis. The layer is restricted to a 24,000 x 24,000 pixel limit. NOTE: The image service uses North America Albers Equal Area Conic projection (WKID: 102008) and resamples the data dynamically to the requested projection, extent and pixel size. For analyses requiring the highest accuracy, when using ArcGIS Pro, you will need to use native coordinates (GCS_North_American_1983, WKID: 4269) and specify the native resolutions (0.0002777777777779 degrees) as the cell size geoprocessing environment setting and ensure that the request is aligned with the source pixels. Server Functions: This layer has server functions defined for the following elevation derivatives. In ArcGIS Pro, server function can be invoked from Layer Properties - Processing Templates. Slope Degrees Slope Percentage Aspect Hillshade Slope Degrees Map This layer has query, identify, and export image services available. The layer is restricted to a 24,000 x 24,000 pixel limit. This layer is part of a larger collection of elevation layers that you can use to perform a variety of mapping and analysis tasks.

本动态影像服务提供以米为单位的地面高程浮点数值，数据源自美国地质调查局（USGS）三维高程项目（3D Elevation Program, 3DEP）的无缝1弧秒数据集。所有高程均为正高（海平面数值为0），高于海平面的水体将采用近似标称水位高度。单位：米；典型更新频率：每年；覆盖范围：美国本土、夏威夷州、阿拉斯加州、波多黎各及美国属地岛屿，同时涵盖加拿大与墨西哥。

数据来源：本图层的数据源自美国地质调查局三维高程项目的无缝1弧秒数据集，原始数据采用其原生坐标系。

本图层可用于以下场景：

可视化用途：本图层通常不适合直接用于可视化。默认返回的32位浮点数值会产生较高的带宽需求，因此其使用应仅限于需要高程数值的应用场景。此外，客户端可调用服务端提供的多种附加功能以获取渲染后的数据。若需制作山体阴影、坡度等可视化效果，建议使用本服务中定义的相应服务端函数。

分析用途：支持分析场景。本图层提供的浮点型高程数值适用于各类分析任务。本图层的处理上限为24000×24000像素。

注意事项：本影像服务采用北美阿尔伯斯等积圆锥投影（WKID: 102008），并会根据请求动态将数据重采样至所需投影、范围与像素尺寸。若需获得最高精度的分析结果，在ArcGIS Pro中需使用原生坐标系（GCS_North_American_1983, WKID: 4269），并将原生分辨率（0.0002777777777779 度）指定为地理处理环境的像元大小设置，同时确保请求与源像素对齐。

服务端函数：本图层支持以下高程衍生产品的服务端函数。在ArcGIS Pro中，可通过「图层属性-处理模板」调用服务端函数：
- 坡度（度）
- 坡度百分比
- 坡向
- 山体阴影
- 坡度度数图

本图层支持查询、识别与导出影像服务功能。本图层同样受限于24000×24000像素的处理上限。本图层隶属于更大范围的高程图层集合，可用于执行各类制图与分析任务。