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 or *.gori files, 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 3d_tiles, 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.

Specification of a non-local coordinate system is also required when a LiDAR Trajectory file is given, as part of LiDAR data complementing the Images input.

 Setting the coordinate system ...

GUI

SURE CLI

--coordinate_system path/to/file/containing/wkt/string.wkt

This file must refer to the input coordinate system, in which the images orientation is. SURE does not convert results to new coordinate systems.

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 set the desired output cell size for raster products using the GSD parameter, taking into consideration also the quality setting. The GSD value specified should be equal or greater than the GSD resulting from the quality setting. Each reduction in quality level doubles the output cell size of the raster products. Exception: output cell size for scenario DEFAULT and quality HIGH is not doubled to allow for full resolution DSM and True Ortho outputs in the standard processing setting.

 Setting the GSD ...

GUI

SURE CLI

--gsd <output gsd>

When using less than 75% forward overlap and less than 50% sideward overlap, 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.