（1）简介
（2）文档参考
Viewshed_sa <in_raster> <in_observer_features> <out_raster> {z_factor} {FLAT_EARTH | CURVED_EARTH} {refractivity_coefficient}
| Parameter | Explanation | Data Type |
| <in_raster> | Input raster. | Composite Geodataset |
| <in_observer_features> | Observer point or polyline features. | Composite Geodataset |
| <out_raster> | The raster to be created. The output will only record the number of times each in_raster location can be seen by the in_observer_features observation points (or vertices for polylines). The observation frequency will be recorded in the VALUE item in the output raster's attribute table. | Raster Dataset |
| {z_factor} | The number of ground x,y units in one surface z unit. The z-factor adjusts the units of measure |
