Project Area

Introduction

This article offers a general description of how SURE handles the Project Area, the different ways it can be defined, and the benefits of using this functionality.

The Project Area demarcates the region of interest so it must be defined in the same coordinate system as the exterior orientation of input images. Selected products will only be generated within the boundaries of the Project Area (e.g. DSM, True Ortho, Point Clouds, Meshes).

Automatic Project Area

If an area is not defined by the user, an area of interest (AOI) shapefile is automatically generated during the Analysis step by default. This shapefile delimits the area where high quality results can be expected based on the input data. This feature can be disabled by unchecking it in the Advanced Configuration dialog. See Region of Interest

Project Area Specified by User

There are three ways to manually define the Project Area:

1. Specify a Shapefile (*.shp) containing a 2D domain which can potentially be defined by multiple 2D polygons. See Shapefiles

2. Define a limiting range along the X, Y, and Z directions. Specify minimum and maximum coordinate values when setting up a project or through the Advance Configuration dialog. See Region of Interest

Optionally, an initial terrain height can be inputted in combination with a 2D area (shapefile or max-min limits). See Region of Interest

Functionality / Benefits

Selection of Input Images

SURE can automatically select the input images that "see" the Project Area if a bounded volume (2D Area + Z range) or a 2D area coupled with a terrain height is specified. Furthermore, SURE performs an image masking, such that only pixels that cover the Project Area will be matched. This feature ensures only the necessary data is used, minimizing processing time and disk space required. Shapefiles with single or multiple polygon features are supported.

Tiling of Results

SURE offers customers the option to define a custom tiling scheme, independently of the actual results area. For more information on how to define a custom tiling scheme origin and tile size please refer to https://nframes.atlassian.net/wiki/spaces/SKB/pages/828604507/Georeferencing+and+Tiling#Defining-the-Project%27s-Tiling-Scheme.

Border quality and consistency

A buffer region (“padding”) is considered along the edges of the Project Area to ensure quality preservation. The additional data generated in this buffer region is used internally to guarantee geometric correctness; however, the final products only contain data falling within the Project Area.

This benefit from padding is also seen in the case of Distributed Processing. The same concept is applied around the area of each sub-project such that there is consistency and smooth transition between them.

Best Practice

It is recommended to define the Project Area whenever possible. Thanks to the automatic image selection and image masking feature, a project’s processing time can be significantly reduced. Common use-cases include:

• A manual specification of the Project Area is almost always applicable, as photogrammetric flights usually capture a somewhat extended area around the actual region of interest. This means there will be an overhead of data to be processed that can easily be discarded.

• With the use of Shapefiles, it is possible to follow complex political boundaries, specify multiple separate areas of interest, or specify areas with 'holes' to exclude sub-areas within the area of interest.

• Because the input images will be automatically selected from the full dataset, tests can be performed rapidly on small areas, on full resolution, to find the best parameters and for prompt Quality Inspection.