Georeferencing and Tiling

Coordinate System

SURE generates georeferenced products whenever the project contains a valid WKT (well-known text) string. All produced tif, las, and laz files contain the georeferencing information assigned to the project.

Whenever the project orientations are specified using a *.prj file, SURE automatically extracts the coordinate system information and uses it for the project. The file coordinate_system.wkt found within the project directory stores the specified WKT string.

The export of Cesium, SLPK, lod_dae, and lod_obj meshes requires a non-local coordinate system. The lod_dae and lod_obj mesh export formats additionally require the "EPSG" field to be within the "PROJCS" field of the WKT string.

 Setting the coordinate system ...

GUI

SURE CLI

--coordinate_system file_containing_wkt_string.wkt

Tile Size and GSD

To allow for efficient and scalable processing, SURE divides the surface to be processed into tiles. These tiles are by default sized in a way that ensures that the hardware requirements are respected.

Manually increasing the tile size too much is likely to lead to a crash during processing. Please only do so if you are confident that your hardware can handle it. One way of doing this is by processing a small area (several tiles) before launching a big project.

The default size of a tile depends on the scenario:

Scenario

Tile Size

AERIAL NADIR

2000 GSDs

AERIAL OBLIQUE

2000 GSDs

DEFAULT

1000 GSDs

The tile size can also be manually defined:

 Setting the tile size ...

GUI

SURE CLI

--tile_size <tile_size>

The GSD (Ground Sampling Distance) of a project is automatically estimated by SURE. Alternatively, users can specify the project's GSD using the graphical user interface or the command-line interface:

 Setting the GSD ...

GUI

SURE CLI

--tile_size <tile_size>

When using the AERIAL Nadir scenario with a forward overlap inferior to 80%, SURE doubles the effective GSD used for sizing the tiles and raster products.

Defining the Project's Tiling Scheme

The top-left corner of the 2D region of interest (automatic or manual if available), together with the tile size, defines the horizontal (XY) tiling of a project.

Knowing this principle, it is possible to control the tiling scheme of the project. With the help of the minimum/maximum values of X,Y and the tile size, you can define the arrangement of the tiles in the XY plane. Please use the area 2D / 3D interfaces to do so.

Note that it is also possible to simultaneously work with an area shape file and define the tiling scheme to your preference.